Bump version

- Remove redundant preservation of cobalt lib constructors. We use
   lambdas now, so this is no longer needed.
 - Fix Java crypto lib not being included.

.editorconfig

@@ -11,5 +11,8 @@ insert_final_newline = true
 [*.md]
 trim_trailing_whitespace = false
 
+[*.sexp]
+indent_size = 2
+
 [*.properties]
 insert_final_newline = false

.github/ISSUE_TEMPLATE/bug_report.md

@@ -1,7 +1,7 @@
 ---
 name: Bug report
 about: Report some misbehaviour in the mod
-
+labels: bug
 ---
 
 <!--

.github/ISSUE_TEMPLATE/feature_request.md

@@ -1,7 +1,7 @@
 ---
 name: Feature request
 about: Suggest an idea or improvement
-
+labels: enhancement
 ---
 
 <!--
@@ -11,4 +11,4 @@ about: Suggest an idea or improvement
 
 ## Useful information to include:
  - Explanation of how the feature/change should work.
- - Some rationale/use case for a feature. I'd like to keep CC:T as minimal as possible, so I like have a solid justification for each feature.
+ - Some rationale/use case for a feature. My general approach to designing new features is to ask yourself "what issue are we trying to solve" and _then_ "is this the best way to solve this issue?".

.github/pull_request_template.md

@@ -0,0 +1,3 @@
+## A quick checklist
+ - If there's a existing issue, please link to it. If not, provide fill out the same information you would in a normal issue - reproduction steps for bugs, rationale for use-case.
+ - If you're working on CraftOS, try to write a few test cases so we can ensure everything continues to work in the future. Tests live in `src/test/resources/test-rom/spec` and can be run with `./gradlew check`.

.github/workflows/main-ci.yml

@@ -0,0 +1,33 @@
+name: Build
+
+on: [push, pull_request]
+
+jobs:
+  build:
+    name: Build
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v1
+
+    - name: Set up JDK 1.8
+      uses: actions/setup-java@v1
+      with:
+        java-version: 1.8
+
+    - name: Build with Gradle
+      run: ./gradlew build --no-daemon
+
+  lint-lua:
+    name: Lint Lua
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v1
+
+    - name: Lint Lua code
+      run: |
+        test -d bin || mkdir bin
+        test -f bin/illuaminate || wget -q -Obin/illuaminate https://squiddev.cc/illuaminate/bin/illuaminate
+        chmod +x bin/illuaminate
+        bin/illuaminate lint

.gitignore

@@ -15,3 +15,9 @@
 .idea
 .gradle
 *.DS_Store
+
+.classpath
+.project
+.settings/
+bin/
+*.launch

.luacheckrc

@@ -1,34 +0,0 @@
-std = "max"
-
-ignore = {
-    -- Allow access to undefined globals or their fields. In the future we'll
-    -- define all of CC's globals within this file
-    '113', '143',
-
-    -- FIXME: Ignore unused arguments and loop variables
-    '212', '213',
-
-    -- Disable line is too long for now. It would be possible to clean
-    -- this up in the future.
-    '631',
-}
-
--- Only run the linter on ROM and bios for now, as the treasure disks
--- are largely unsupported.
-include_files = {
-    'src/main/resources/assets/computercraft/lua/rom',
-    'src/main/resources/assets/computercraft/lua/bios.lua'
-}
-
-files['src/main/resources/assets/computercraft/lua/bios.lua'] = {
-    -- Allow declaring and mutating globals
-    allow_defined_top = true,
-    ignore = { '112', '121', '122', '131', '142' },
-}
-
-files['src/main/resources/assets/computercraft/lua/rom/apis'] = {
-    -- APIs may define globals on the top level. We'll ignore unused globals,
-    -- as obviously they may be used outside that API.
-    allow_defined_top = true,
-    ignore = { '131' },
-}

.travis.yml

@@ -1,14 +0,0 @@
-language: java
-
-script: ./gradlew build --no-daemon
-
-before_cache:
-  - rm -f  $HOME/.gradle/caches/modules-2/modules-2.lock
-  - rm -fr $HOME/.gradle/caches/*/plugin-resolution/
-cache:
-  directories:
-    - $HOME/.gradle/caches/
-    - $HOME/.gradle/wrapper/s
-
-jdk:
-    - oraclejdk8

README.md

@@ -1,5 +1,5 @@
 # ![CC: Tweaked](logo.png)
-[![Build Status](https://travis-ci.org/SquidDev-CC/CC-Tweaked.svg?branch=master)](https://travis-ci.org/SquidDev-CC/CC-Tweaked)
+[![Current build status](https://github.com/SquidDev-CC/CC-Tweaked/workflows/Build/badge.svg)](https://github.com/SquidDev-CC/CC-Tweaked/actions "Current build status") [![Download CC: Tweaked on CurseForge](http://cf.way2muchnoise.eu/title/cc-tweaked.svg)](https://minecraft.curseforge.com/projects/cc-tweaked "Download CC: Tweaked on CurseForge")
 
 CC: Tweaked is a fork of [ComputerCraft](https://github.com/dan200/ComputerCraft), adding programmable computers,
 turtles and more to Minecraft.
@@ -9,7 +9,7 @@ ComputerCraft has always held a fond place in my heart: it's the mod which reall
 mod which has kept me playing it for many years. However, development of the original mod has slowed, as the original
 developers have had less time to work on the mod, and moved onto other projects and commitments.
 
-CC:Tweaked (or CC:T for short) is an attempt to continue ComputerCraft's legacy. It's not intended to be a competitor
+CC: Tweaked (or CC:T for short) is an attempt to continue ComputerCraft's legacy. It's not intended to be a competitor
 to CC, nor do I want to take it in a vastly different direction to the original mod. Instead, CC:T focuses on making the
 ComputerCraft experience as _solid_ as possible, ironing out any wrinkles that may have developed over time.
 
@@ -46,8 +46,17 @@ develop CC:T, you'll need to follow these steps:
 
 If you want to run CC:T in a normal Minecraft instance, run `./gradlew build` and copy the `.jar` from `build/libs`.
 
+## Community
+If you need help getting started with CC: Tweaked, want to show off your latest project, or just want to chat about
+ComputerCraft we have a [forum](https://forums.computercraft.cc/) and [Discord guild](https://discord.gg/H2UyJXe)!
+There's also a fairly populated, albeit quiet [IRC channel](http://webchat.esper.net/?channels=#computercraft), if
+that's more your cup of tea.
+
+I'd generally recommend you don't contact me directly (email, DM, etc...) unless absolutely necessary (i.e. in order to
+report exploits). You'll get a far quicker response if you ask the whole community!
+
 ## Using
-If you want to depend on CC:Tweaked, we have a maven repo. However, you should be wary that some functionality is only
+If you want to depend on CC: Tweaked, we have a maven repo. However, you should be wary that some functionality is only
 exposed by CC:T's API and not vanilla ComputerCraft. If you wish to support all variations of ComputerCraft, I recommend
 using [cc.crzd.me's maven](https://cc.crzd.me/maven/) instead.
 
@@ -57,7 +66,7 @@ dependencies {
 }
 
 dependencies {
-  implementation "org.squiddev:cc-tweaked:${mc_version}-${cct_version}"
+  implementation "org.squiddev:cc-tweaked-${mc_version}:${cct_version}"
 }
 ```
 

build.gradle

@@ -5,7 +5,7 @@ buildscript {
         jcenter()
         maven {
             name = "forge"
-            url = "http://files.minecraftforge.net/maven"
+            url = "https://files.minecraftforge.net/maven"
         }
     }
     dependencies {
@@ -17,7 +17,10 @@ buildscript {
 }
 
 plugins {
-    id 'com.matthewprenger.cursegradle' version '1.0.10'
+    id "checkstyle"
+    id "com.github.hierynomus.license" version "0.15.0"
+    id "com.matthewprenger.cursegradle" version "1.3.0"
+    id "com.github.breadmoirai.github-release" version "2.2.4"
 }
 
 apply plugin: 'net.minecraftforge.gradle.forge'
@@ -42,7 +45,7 @@ minecraft {
 repositories {
     maven {
         name "JEI"
-        url "http://dvs1.progwml6.com/files/maven"
+        url "https://dvs1.progwml6.com/files/maven"
     }
     maven {
         name "SquidDev"
@@ -54,7 +57,11 @@ repositories {
     }
     maven {
         name "Amadornes"
-        url "http://maven.amadornes.com/"
+        url "https://maven.amadornes.com/"
+    }
+    maven {
+        name "CraftTweaker"
+        url "https://maven.blamejared.com/"
     }
 }
 
@@ -65,20 +72,25 @@ configurations {
 }
 
 dependencies {
+    checkstyle "com.puppycrawl.tools:checkstyle:8.25"
+
+    deobfProvided "CraftTweaker2:CraftTweaker2-MC1120-Main:1.12-4.1.20.554"
+    deobfProvided "MCMultiPart2:MCMultiPart:2.5.3"
     deobfProvided "mezz.jei:jei_1.12.2:4.15.0.269:api"
     deobfProvided "pl.asie:Charset-Lib:0.5.4.6"
-    deobfProvided "MCMultiPart2:MCMultiPart:2.5.3"
 
     runtime "mezz.jei:jei_1.12.2:4.15.0.269"
 
     shade 'org.squiddev:Cobalt:0.5.0-SNAPSHOT'
 
-    testImplementation 'org.junit.jupiter:junit-jupiter-api:5.1.0'
-    testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine:5.1.0'
+    testImplementation 'org.junit.jupiter:junit-jupiter-api:5.4.2'
+    testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine:5.4.2'
 
     deployerJars "org.apache.maven.wagon:wagon-ssh:3.0.0"
 }
 
+// Compile tasks
+
 javadoc {
     include "dan200/computercraft/api/**/*.java"
 }
@@ -97,12 +109,22 @@ jar {
     from configurations.shade.collect { it.isDirectory() ? it : zipTree(it) }
 }
 
+[compileJava, compileTestJava].forEach {
+    it.configure {
+        options.compilerArgs << "-Xlint" << "-Xlint:-processing" << "-Werror"
+    }
+}
+
+
+
 import java.nio.charset.StandardCharsets
 import java.nio.file.*
 import java.util.zip.*
 
 import com.google.gson.GsonBuilder
 import com.google.gson.JsonElement
+import com.hierynomus.gradle.license.tasks.LicenseCheck
+import com.hierynomus.gradle.license.tasks.LicenseFormat
 import org.ajoberstar.grgit.Grgit
 import proguard.gradle.ProGuardTask
 
@@ -115,6 +137,7 @@ task proguard(type: ProGuardTask, dependsOn: jar) {
 
     // Add the main runtime jar and all non-shadowed dependencies
     libraryjars "${System.getProperty('java.home')}/lib/rt.jar"
+    libraryjars "${System.getProperty('java.home')}/lib/jce.jar"
     doFirst {
         sourceSets.main.compileClasspath
             .filter { !it.name.contains("Cobalt") }
@@ -129,9 +152,6 @@ task proguard(type: ProGuardTask, dependsOn: jar) {
 
     // Preserve ComputerCraft classes - we only want to strip shadowed files.
     keep 'class dan200.computercraft.** { *; }'
-
-    // Preserve the constructors in Cobalt library class, as we init them via reflection
-    keepclassmembers 'class org.squiddev.cobalt.lib.** { <init>(...); }'
 }
 
 task proguardMove(dependsOn: proguard) {
@@ -198,6 +218,7 @@ task compressJson(dependsOn: extractAnnotationsJar) {
         // Copy over all files in the current jar to the new one, running json files from GSON. As pretty printing
         // is turned off, they should be minified.
         new ZipFile(jarPath).withCloseable { inJar ->
+            tempPath.getParentFile().mkdirs()
             new ZipOutputStream(new BufferedOutputStream(new FileOutputStream(tempPath))).withCloseable { outJar ->
                 inJar.entries().each { entry ->
                     if(entry.directory) {
@@ -225,12 +246,106 @@ task compressJson(dependsOn: extractAnnotationsJar) {
 
 assemble.dependsOn compressJson
 
+// Check tasks
+
+test {
+    useJUnitPlatform()
+    testLogging {
+        events "skipped", "failed"
+    }
+}
+
+license {
+    mapping("java", "SLASHSTAR_STYLE")
+    strictCheck true
+
+    ext.year = Calendar.getInstance().get(Calendar.YEAR)
+}
+
+[licenseMain, licenseFormatMain].forEach {
+    it.configure {
+        include("**/*.java")
+        exclude("dan200/computercraft/api/**")
+        header rootProject.file('config/license/main.txt')
+    }
+}
+
+[licenseTest, licenseFormatTest].forEach {
+    it.configure {
+        include("**/*.java")
+        header rootProject.file('config/license/main.txt')
+    }
+}
+
+gradle.projectsEvaluated {
+    tasks.withType(LicenseFormat) {
+        outputs.upToDateWhen { false }
+    }
+}
+
+
+task licenseAPI(type: LicenseCheck);
+task licenseFormatAPI(type: LicenseFormat);
+[licenseAPI, licenseFormatAPI].forEach {
+    it.configure {
+        source = sourceSets.main.java
+        include("dan200/computercraft/api/**")
+        header rootProject.file('config/license/api.txt')
+    }
+}
+
+// Upload tasks
+
+task checkRelease {
+    group "upload"
+    description "Verifies that everything is ready for a release"
+
+    inputs.property "version", mod_version
+    inputs.file("src/main/resources/assets/computercraft/lua/rom/help/changelog.txt")
+    inputs.file("src/main/resources/assets/computercraft/lua/rom/help/whatsnew.txt")
+
+    doLast {
+        def ok = true
+
+        // Check we're targetting the current version
+        def whatsnew = new File("src/main/resources/assets/computercraft/lua/rom/help/whatsnew.txt").readLines()
+        if (whatsnew[0] != "New features in CC: Tweaked $mod_version") {
+            ok = false
+            project.logger.error("Expected `whatsnew.txt' to target $mod_version.")
+        }
+
+        // Check "read more" exists and trim it
+        def idx = whatsnew.findIndexOf { it == 'Type "help changelog" to see the full version history.' }
+        if (idx == -1) {
+            ok = false
+            project.logger.error("Must mention the changelog in whatsnew.txt")
+        } else {
+            whatsnew = whatsnew.getAt(0 ..< idx)
+        }
+
+        // Check whatsnew and changelog match.
+        def versionChangelog = "# " + whatsnew.join("\n")
+        def changelog = new File("src/main/resources/assets/computercraft/lua/rom/help/changelog.txt").getText()
+        if (!changelog.startsWith(versionChangelog)) {
+            ok = false
+            project.logger.error("whatsnew and changelog are not in sync")
+        }
+
+        if (!ok) throw new IllegalStateException("Could not check release")
+    }
+}
+check.dependsOn checkRelease
+
 curseforge {
     apiKey = project.hasProperty('curseForgeApiKey') ? project.curseForgeApiKey : ''
     project {
         id = '282001'
         releaseType = 'release'
-        changelog = "Release notes can be found on the GitHub repository (https://github.com/SquidDev-CC/CC-Tweaked/releases/tag/v${project.version})."
+        changelog = "Release notes can be found on the GitHub repository (https://github.com/SquidDev-CC/CC-Tweaked/releases/tag/v${mc_version}-${mod_version})."
+
+        relations {
+            incompatible "computercraft"
+        }
     }
 }
 
@@ -287,17 +402,31 @@ uploadArchives {
     }
 }
 
-test {
-    useJUnitPlatform()
-    testLogging {
-        events "passed", "skipped", "failed"
+githubRelease {
+    token project.hasProperty('githubApiKey') ? project.githubApiKey : ''
+    owner 'SquidDev-CC'
+    repo 'CC-Tweaked'
+    try {
+        targetCommitish = Grgit.open(dir: '.').branch.current().name
+    } catch(Exception ignored) { }
+
+    tagName "v${mc_version}-${mod_version}"
+    releaseName "[${mc_version}] ${mod_version}"
+    body {
+        "## " + new File("src/main/resources/assets/computercraft/lua/rom/help/whatsnew.txt")
+            .readLines()
+            .takeWhile { it != 'Type "help changelog" to see the full version history.' }
+            .join("\n").trim()
     }
+    prerelease false
 }
 
-gradle.projectsEvaluated {
-    tasks.withType(JavaCompile) {
-        options.compilerArgs << "-Xlint" << "-Xlint:-processing" << "-Werror"
-    }
+def uploadTasks = ["uploadArchives", "curseforge", "githubRelease"]
+uploadTasks.forEach { tasks.getByName(it).dependsOn checkRelease }
+
+task uploadAll(dependsOn: uploadTasks) {
+    group "upload"
+    description "Uploads to all repositories (Maven, Curse, GitHub release)"
 }
 
 runClient.outputs.upToDateWhen { false }

config/checkstyle/checkstyle.xml

@@ -0,0 +1,169 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE module PUBLIC
+    "-//Checkstyle//DTD Checkstyle Configuration 1.3//EN"
+    "https://checkstyle.org/dtds/configuration_1_3.dtd">
+<module name="Checker">
+    <property name="tabWidth" value="4"/>
+    <property name="charset" value="UTF-8" />
+
+    <module name="SuppressionFilter">
+        <property name="file" value="config/checkstyle/suppressions.xml" />
+    </module>
+
+    <module name="TreeWalker">
+        <!-- Annotations -->
+        <module name="AnnotationLocation" />
+        <module name="AnnotationUseStyle" />
+        <module name="MissingDeprecated" />
+        <module name="MissingOverride" />
+
+        <!-- Blocks -->
+        <module name="EmptyBlock" />
+        <module name="EmptyCatchBlock">
+            <property name="exceptionVariableName" value="ignored" />
+        </module>
+        <module name="LeftCurly">
+            <property name="option" value="nl" />
+            <!-- The defaults, minus lambdas. -->
+            <property name="tokens" value="ANNOTATION_DEF,CLASS_DEF,CTOR_DEF,ENUM_CONSTANT_DEF,ENUM_DEF,INTERFACE_DEF,LITERAL_CASE,LITERAL_CATCH,LITERAL_DEFAULT,LITERAL_DO,LITERAL_ELSE,LITERAL_FINALLY,LITERAL_FOR,LITERAL_IF,LITERAL_SWITCH,LITERAL_SYNCHRONIZED,LITERAL_TRY,LITERAL_WHILE,METHOD_DEF,OBJBLOCK,STATIC_INIT" />
+        </module>
+        <module name="NeedBraces">
+            <property name="allowSingleLineStatement" value="true"/>
+        </module>
+        <module name="RightCurly">
+            <property name="option" value="alone" />
+        </module>
+
+        <!-- Class design. As if we've ever followed good practice here. -->
+        <module name="FinalClass" />
+        <module name="InterfaceIsType" />
+        <module name="MutableException" />
+        <module name="OneTopLevelClass" />
+
+        <!-- Coding -->
+        <module name="ArrayTrailingComma" />
+        <module name="EqualsHashCode" />
+        <!-- FallThrough does not handle unreachable code well -->
+        <module name="IllegalInstantiation" />
+        <module name="IllegalThrows" />
+        <module name="ModifiedControlVariable" />
+        <module name="NoClone" />
+        <module name="NoFinalizer" />
+        <module name="OneStatementPerLine" />
+        <module name="PackageDeclaration" />
+        <module name="SimplifyBooleanExpression" />
+        <module name="SimplifyBooleanReturn" />
+        <module name="StringLiteralEquality" />
+        <module name="UnnecessaryParentheses" />
+        <module name="UnnecessarySemicolonAfterTypeMemberDeclaration" />
+        <module name="UnnecessarySemicolonInTryWithResources" />
+        <module name="UnnecessarySemicolonInEnumeration" />
+
+        <!-- Imports -->
+        <module name="CustomImportOrder" />
+        <module name="IllegalImport" />
+        <module name="RedundantImport" />
+        <module name="UnusedImports" />
+
+        <!-- Javadoc -->
+        <!-- TODO: Missing* checks for the dan200.computercraft.api package? -->
+        <module name="AtclauseOrder" />
+        <module name="InvalidJavadocPosition" />
+        <module name="JavadocBlockTagLocation" />
+        <module name="JavadocMethod"/>
+        <module name="JavadocType"/>
+        <module name="JavadocStyle" />
+        <module name="NonEmptyAtclauseDescription" />
+        <module name="SingleLineJavadoc" />
+        <module name="SummaryJavadocCheck"/>
+
+        <!-- Misc -->
+        <module name="ArrayTypeStyle" />
+        <module name="CommentsIndentation" />
+        <module name="Indentation" />
+        <module name="OuterTypeFilename" />
+
+        <!-- Modifiers -->
+        <module name="ModifierOrder" />
+        <module name="RedundantModifier" />
+
+        <!-- Naming -->
+        <module name="ClassTypeParameterName" />
+        <module name="InterfaceTypeParameterName" />
+        <module name="LambdaParameterName" />
+        <module name="LocalFinalVariableName" />
+        <module name="LocalVariableName" />
+        <!-- Allow an optional m_ on private members -->
+        <module name="MemberName">
+            <property name="applyToPrivate" value="false" />
+            <property name="applyToPackage" value="false" />
+        </module>
+        <module name="MemberName">
+            <property name="format" value="^(m_)?[a-z][a-zA-Z0-9]*$" />
+            <property name="applyToPrivate" value="true" />
+            <property name="applyToPackage" value="true" />
+        </module>
+        <module name="MethodName" />
+        <module name="MethodTypeParameterName" />
+        <module name="PackageName">
+            <property name="format" value="^dan200\.computercraf(\.[a-z][a-z0-9]*)*" />
+        </module>
+        <module name="ParameterName" />
+        <module name="StaticVariableName">
+            <property name="format" value="^[a-z][a-zA-Z0-9]*|CAPABILITY(_[A-Z]+)?$" />
+            <property name="applyToPrivate" value="false" />
+        </module>
+        <module name="StaticVariableName">
+            <property name="format" value="^(s_)?[a-z][a-zA-Z0-9]*|CAPABILITY(_[A-Z]+)?$" />
+            <property name="applyToPrivate" value="true" />
+        </module>
+        <module name="TypeName" />
+
+        <!-- Whitespace -->
+        <module name="EmptyForInitializerPad"/>
+        <module name="EmptyForIteratorPad">
+            <property name="option" value="space"/>
+        </module>
+        <module name="GenericWhitespace" />
+        <module name="MethodParamPad" />
+        <module name="NoLineWrap" />
+        <module name="NoWhitespaceAfter">
+            <property name="tokens" value="AT,INC,DEC,UNARY_MINUS,UNARY_PLUS,BNOT,LNOT,DOT,ARRAY_DECLARATOR,INDEX_OP" />
+        </module>
+        <module name="NoWhitespaceBefore" />
+        <!-- TODO: Decide on an OperatorWrap style. -->
+        <module name="ParenPad">
+            <property name="option" value="space" />
+            <property name="tokens" value="ANNOTATION,ANNOTATION_FIELD_DEF,CTOR_CALL,CTOR_DEF,ENUM_CONSTANT_DEF,LITERAL_CATCH,LITERAL_DO,LITERAL_FOR,LITERAL_IF,LITERAL_NEW,LITERAL_SWITCH,LITERAL_SYNCHRONIZED,LITERAL_WHILE,METHOD_CALL,METHOD_DEF,RESOURCE_SPECIFICATION,SUPER_CTOR_CALL,LAMBDA" />
+        </module>
+        <module name="ParenPad">
+            <property name="option" value="nospace" />
+            <property name="tokens" value="DOT,EXPR,QUESTION" />
+        </module>
+        <module name="SeparatorWrap">
+            <property name="option" value="eol" />
+            <property name="tokens" value="COMMA,SEMI,ELLIPSIS,ARRAY_DECLARATOR,RBRACK,METHOD_REF" />
+        </module>
+        <module name="SeparatorWrap">
+            <property name="option" value="nl" />
+            <property name="tokens" value="DOT,AT" />
+        </module>
+        <module name="SingleSpaceSeparator" />
+        <module name="TypecastParenPad" />
+        <module name="WhitespaceAfter">
+            <property name="tokens" value="COMMA" />
+        </module>
+        <module name="WhitespaceAround">
+            <property name="allowEmptyConstructors" value="true" />
+            <property name="ignoreEnhancedForColon" value="false" />
+            <property name="tokens" value="ASSIGN,BAND,BAND_ASSIGN,BOR,BOR_ASSIGN,BSR,BSR_ASSIGN,BXOR,BXOR_ASSIGN,COLON,DIV,DIV_ASSIGN,DO_WHILE,EQUAL,GE,GT,LAMBDA,LAND,LCURLY,LE,LITERAL_RETURN,LOR,LT,MINUS,MINUS_ASSIGN,MOD,MOD_ASSIGN,NOT_EQUAL,PLUS,PLUS_ASSIGN,QUESTION,RCURLY,SL,SLIST,SL_ASSIGN,SR,SR_ASSIGN,STAR,STAR_ASSIGN,LITERAL_ASSERT,TYPE_EXTENSION_AND" />
+        </module>
+    </module>
+
+    <module name="FileTabCharacter" />
+    <module name="NewlineAtEndOfFile" />
+    <module name="RegexpSingleline">
+        <property name="format" value="\s+$"/>
+        <property name="message" value="Trailing whitespace"/>
+    </module>
+</module>

config/checkstyle/suppressions.xml

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE suppressions PUBLIC
+    "-//Checkstyle//DTD SuppressionFilter Configuration 1.2//EN"
+    "https://checkstyle.org/dtds/suppressions_1_2.dtd">
+<suppressions>
+    <!-- All the config options and method fields. -->
+    <suppress checks="StaticVariableName" files=".*[\\/]ComputerCraft.java" />
+    <suppress checks="StaticVariableName" files=".*[\\/]ComputerCraftAPI.java" />
+
+    <!-- Do not check for missing package Javadoc. -->
+    <suppress checks="JavadocStyle" files=".*[\\/]package-info.java" />
+</suppressions>

config/license/api.txt

@@ -0,0 +1,3 @@
+This file is part of the public ComputerCraft API - http://www.computercraft.info
+Copyright Daniel Ratcliffe, 2011-${year}. This API may be redistributed unmodified and in full only.
+For help using the API, and posting your mods, visit the forums at computercraft.info.

config/license/main.txt

@@ -0,0 +1,3 @@
+This file is part of ComputerCraft - http://www.computercraft.info
+Copyright Daniel Ratcliffe, 2011-${year}. Do not distribute without permission.
+Send enquiries to dratcliffe@gmail.com

gradle.properties

@@ -1,5 +1,5 @@
 # Mod properties
-mod_version=1.82.0
+mod_version=1.86.0
 
 # Minecraft properties
 mc_version=1.12.2

illuaminate.sexp

@@ -0,0 +1,28 @@
+; -*- mode: Lisp;-*-
+
+(sources
+  /src/main/resources/assets/computercraft/lua/bios.lua
+  /src/main/resources/assets/computercraft/lua/rom/
+  /src/test/resources/test-rom)
+
+(at /
+  (linters
+    ;; It'd be nice to avoid this, but right now there's a lot of instances of
+    ;; it.
+    -var:set-loop
+
+    ;; It's useful to name arguments for documentation, so we allow this. It'd
+    ;; be good to find a compromise in the future, but this works for now.
+    -var:unused-arg))
+
+;; We disable the unused global linter in bios.lua and the APIs. In the future
+;; hopefully we'll get illuaminate to handle this.
+(at
+  (/src/main/resources/assets/computercraft/lua/bios.lua
+   /src/main/resources/assets/computercraft/lua/rom/apis/)
+  (linters -var:unused-global)
+  (lint
+    (allow-toplevel-global true)))
+
+;; These warnings are broken right now
+(at (bios.lua worm.lua) (linters -control:unreachable))

src/main/java/dan200/computercraft/ComputerCraft.java

@@ -72,9 +72,7 @@ import net.minecraft.util.math.BlockPos;
 import net.minecraft.world.IBlockAccess;
 import net.minecraft.world.World;
 import net.minecraftforge.common.DimensionManager;
-import net.minecraftforge.fml.common.FMLCommonHandler;
-import net.minecraftforge.fml.common.Mod;
-import net.minecraftforge.fml.common.SidedProxy;
+import net.minecraftforge.fml.common.*;
 import net.minecraftforge.fml.common.event.*;
 import net.minecraftforge.fml.relauncher.Side;
 import org.apache.logging.log4j.Logger;
@@ -83,9 +81,7 @@ import java.io.*;
 import java.net.MalformedURLException;
 import java.net.URISyntaxException;
 import java.net.URL;
-import java.util.ArrayList;
-import java.util.EnumSet;
-import java.util.List;
+import java.util.*;
 import java.util.concurrent.TimeUnit;
 import java.util.zip.ZipEntry;
 import java.util.zip.ZipFile;
@@ -394,6 +390,27 @@ public class ComputerCraft
         }
     }
 
+    private static void loadFromFile( List<IMount> mounts, File file, String path, boolean allowMissing )
+    {
+        try
+        {
+            if( file.isFile() )
+            {
+                mounts.add( new JarMount( file, path ) );
+            }
+            else
+            {
+                File subResource = new File( file, path );
+                if( subResource.exists() ) mounts.add( new FileMount( subResource, 0 ) );
+            }
+        }
+        catch( IOException | RuntimeException e )
+        {
+            if( allowMissing && e instanceof FileNotFoundException ) return;
+            ComputerCraft.log.error( "Could not load mount '" + path + " 'from '" + file.getName() + "'", e );
+        }
+    }
+
     @Deprecated
     public static IMount createResourceMount( Class<?> modClass, String domain, String subPath )
     {
@@ -413,18 +430,26 @@ public class ComputerCraft
             }
         }
 
-        // Mount from mod jar
+        // Mount from mod jars, preferring the specified one.
         File modJar = getContainingJar( modClass );
+        Set<File> otherMods = new HashSet<>();
+        for( ModContainer container : Loader.instance().getActiveModList() )
+        {
+            File modFile = container.getSource();
+            if( modFile != null && !modFile.equals( modJar ) && modFile.exists() )
+            {
+                otherMods.add( container.getSource() );
+            }
+        }
+
+        for( File file : otherMods )
+        {
+            loadFromFile( mounts, file, subPath, true );
+        }
+
         if( modJar != null )
         {
-            try
-            {
-                mounts.add( new JarMount( modJar, subPath ) );
-            }
-            catch( IOException | RuntimeException e )
-            {
-                ComputerCraft.log.error( "Could not load mount from mod jar", e );
-            }
+            loadFromFile( mounts, modJar, subPath, false );
         }
 
         // Mount from resource packs
@@ -434,25 +459,8 @@ public class ComputerCraft
             String[] resourcePacks = resourcePackDir.list();
             for( String resourcePackName : resourcePacks )
             {
-                try
-                {
-                    File resourcePack = new File( resourcePackDir, resourcePackName );
-                    if( !resourcePack.isDirectory() )
-                    {
-                        // Mount a resource pack from a jar
-                        mounts.add( new JarMount( resourcePack, subPath ) );
-                    }
-                    else
-                    {
-                        // Mount a resource pack from a folder
-                        File subResource = new File( resourcePack, subPath );
-                        if( subResource.exists() ) mounts.add( new FileMount( subResource, 0 ) );
-                    }
-                }
-                catch( IOException | RuntimeException e )
-                {
-                    ComputerCraft.log.error( "Could not load resource pack '" + resourcePackName + "'", e );
-                }
+                File resourcePack = new File( resourcePackDir, resourcePackName );
+                loadFromFile( mounts, resourcePack, subPath, true );
             }
         }
 

src/main/java/dan200/computercraft/api/AbstractTurtleUpgrade.java

@@ -1,9 +1,8 @@
 /*
- * This file is part of ComputerCraft - http://www.computercraft.info
- * Copyright Daniel Ratcliffe, 2011-2019. Do not distribute without permission.
- * Send enquiries to dratcliffe@gmail.com
+ * This file is part of the public ComputerCraft API - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2019. This API may be redistributed unmodified and in full only.
+ * For help using the API, and posting your mods, visit the forums at computercraft.info.
  */
-
 package dan200.computercraft.api;
 
 import dan200.computercraft.api.turtle.ITurtleUpgrade;

src/main/java/dan200/computercraft/api/ComputerCraftAPI.java

@@ -32,8 +32,9 @@ import java.lang.reflect.Method;
 
 /**
  * The static entry point to the ComputerCraft API.
- * Members in this class must be called after mod_ComputerCraft has been initialised,
- * but may be called before it is fully loaded.
+ *
+ * Members in this class must be called after mod_ComputerCraft has been initialised, but may be called before it is
+ * fully loaded.
  */
 public final class ComputerCraftAPI
 {
@@ -269,7 +270,7 @@ public final class ComputerCraftAPI
     }
 
     /**
-     * Registers a media provider to provide {@link IMedia} implementations for Items
+     * Registers a media provider to provide {@link IMedia} implementations for Items.
      *
      * @param provider The media provider to register.
      * @see IMediaProvider
@@ -370,7 +371,7 @@ public final class ComputerCraftAPI
     }
 
     /**
-     * Construct a new wired node for a given wired element
+     * Construct a new wired node for a given wired element.
      *
      * @param element The element to construct it for
      * @return The element's node
@@ -398,7 +399,7 @@ public final class ComputerCraftAPI
     }
 
     /**
-     * Get the wired network element for a block in world
+     * Get the wired network element for a block in world.
      *
      * @param world The world the block exists in
      * @param pos   The position the block exists in
@@ -438,45 +439,45 @@ public final class ComputerCraftAPI
                 computerCraft_getVersion = findCCMethod( "getVersion", new Class<?>[] {
                 } );
                 computerCraft_createUniqueNumberedSaveDir = findCCMethod( "createUniqueNumberedSaveDir", new Class<?>[] {
-                    World.class, String.class
+                    World.class, String.class,
                 } );
                 computerCraft_createSaveDirMount = findCCMethod( "createSaveDirMount", new Class<?>[] {
-                    World.class, String.class, Long.TYPE
+                    World.class, String.class, Long.TYPE,
                 } );
                 computerCraft_createResourceMount = findCCMethod( "createResourceMount", new Class<?>[] {
-                    Class.class, String.class, String.class
+                    Class.class, String.class, String.class,
                 } );
                 computerCraft_registerPeripheralProvider = findCCMethod( "registerPeripheralProvider", new Class<?>[] {
-                    IPeripheralProvider.class
+                    IPeripheralProvider.class,
                 } );
                 computerCraft_registerTurtleUpgrade = findCCMethod( "registerTurtleUpgrade", new Class<?>[] {
-                    ITurtleUpgrade.class
+                    ITurtleUpgrade.class,
                 } );
                 computerCraft_registerBundledRedstoneProvider = findCCMethod( "registerBundledRedstoneProvider", new Class<?>[] {
-                    IBundledRedstoneProvider.class
+                    IBundledRedstoneProvider.class,
                 } );
                 computerCraft_getDefaultBundledRedstoneOutput = findCCMethod( "getDefaultBundledRedstoneOutput", new Class<?>[] {
-                    World.class, BlockPos.class, EnumFacing.class
+                    World.class, BlockPos.class, EnumFacing.class,
                 } );
                 computerCraft_registerMediaProvider = findCCMethod( "registerMediaProvider", new Class<?>[] {
-                    IMediaProvider.class
+                    IMediaProvider.class,
                 } );
                 computerCraft_registerPermissionProvider = findCCMethod( "registerPermissionProvider", new Class<?>[] {
-                    ITurtlePermissionProvider.class
+                    ITurtlePermissionProvider.class,
                 } );
                 computerCraft_registerPocketUpgrade = findCCMethod( "registerPocketUpgrade", new Class<?>[] {
-                    IPocketUpgrade.class
+                    IPocketUpgrade.class,
                 } );
                 computerCraft_getWirelessNetwork = findCCMethod( "getWirelessNetwork", new Class<?>[] {
                 } );
                 computerCraft_registerAPIFactory = findCCMethod( "registerAPIFactory", new Class<?>[] {
-                    ILuaAPIFactory.class
+                    ILuaAPIFactory.class,
                 } );
                 computerCraft_createWiredNodeForElement = findCCMethod( "createWiredNodeForElement", new Class<?>[] {
-                    IWiredElement.class
+                    IWiredElement.class,
                 } );
                 computerCraft_getWiredElementAt = findCCMethod( "getWiredElementAt", new Class<?>[] {
-                    IBlockAccess.class, BlockPos.class, EnumFacing.class
+                    IBlockAccess.class, BlockPos.class, EnumFacing.class,
                 } );
             }
             catch( Exception e )

src/main/java/dan200/computercraft/api/filesystem/FileOperationException.java

@@ -0,0 +1,41 @@
+/*
+ * This file is part of the public ComputerCraft API - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2019. This API may be redistributed unmodified and in full only.
+ * For help using the API, and posting your mods, visit the forums at computercraft.info.
+ */
+package dan200.computercraft.api.filesystem;
+
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+import java.io.IOException;
+import java.util.Objects;
+
+/**
+ * An {@link IOException} which occurred on a specific file.
+ *
+ * This may be thrown from a {@link IMount} or {@link IWritableMount} to give more information about a failure.
+ */
+public class FileOperationException extends IOException
+{
+    private static final long serialVersionUID = -8809108200853029849L;
+
+    private final String filename;
+
+    public FileOperationException( @Nullable String filename, @Nonnull String message )
+    {
+        super( Objects.requireNonNull( message, "message cannot be null" ) );
+        this.filename = filename;
+    }
+
+    public FileOperationException( String message )
+    {
+        super( Objects.requireNonNull( message, "message cannot be null" ) );
+        this.filename = null;
+    }
+
+    @Nullable
+    public String getFilename()
+    {
+        return filename;
+    }
+}

src/main/java/dan200/computercraft/api/filesystem/IMount.java

@@ -19,7 +19,7 @@ import java.util.List;
 
 /**
  * Represents a read only part of a virtual filesystem that can be mounted onto a computer using
- * {@link IComputerAccess#mount(String, IMount)}
+ * {@link IComputerAccess#mount(String, IMount)}.
  *
  * Ready made implementations of this interface can be created using
  * {@link ComputerCraftAPI#createSaveDirMount(World, String, long)} or
@@ -60,7 +60,7 @@ public interface IMount
     void list( @Nonnull String path, @Nonnull List<String> contents ) throws IOException;
 
     /**
-     * Returns the size of a file with a given path, in bytes
+     * Returns the size of a file with a given path, in bytes.
      *
      * @param path A file path in normalised format, relative to the mount location. ie: "programs/myprogram".
      * @return The size of the file, in bytes.
@@ -90,7 +90,6 @@ public interface IMount
      * @throws IOException If the file does not exist, or could not be opened.
      */
     @Nonnull
-    @SuppressWarnings( "deprecation" )
     default ReadableByteChannel openChannelForRead( @Nonnull String path ) throws IOException
     {
         return Channels.newChannel( openForRead( path ) );

src/main/java/dan200/computercraft/api/filesystem/IWritableMount.java

@@ -67,7 +67,6 @@ public interface IWritableMount extends IMount
      * @throws IOException If the file could not be opened for writing.
      */
     @Nonnull
-    @SuppressWarnings( "deprecation" )
     default WritableByteChannel openChannelForWrite( @Nonnull String path ) throws IOException
     {
         return Channels.newChannel( openForWrite( path ) );
@@ -94,7 +93,6 @@ public interface IWritableMount extends IMount
      * @throws IOException If the file could not be opened for writing.
      */
     @Nonnull
-    @SuppressWarnings( "deprecation" )
     default WritableByteChannel openChannelForAppend( @Nonnull String path ) throws IOException
     {
         return Channels.newChannel( openForAppend( path ) );

src/main/java/dan200/computercraft/api/lua/ArgumentHelper.java

@@ -0,0 +1,335 @@
+/*
+ * This file is part of the public ComputerCraft API - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2019. This API may be redistributed unmodified and in full only.
+ * For help using the API, and posting your mods, visit the forums at computercraft.info.
+ */
+
+package dan200.computercraft.api.lua;
+
+import dan200.computercraft.api.peripheral.IComputerAccess;
+import dan200.computercraft.api.peripheral.IPeripheral;
+
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+import java.util.Map;
+
+/**
+ * Provides methods for extracting values and validating Lua arguments, such as those provided to
+ * {@link ILuaObject#callMethod(ILuaContext, int, Object[])} or
+ * {@link IPeripheral#callMethod(IComputerAccess, ILuaContext, int, Object[])}.
+ *
+ * This provides two sets of functions: the {@code get*} methods, which require an argument to be valid, and
+ * {@code opt*}, which accept a default value and return that if the argument was not present or was {@code null}.
+ * If the argument is of the wrong type, a suitable error message will be thrown, with a similar format to Lua's own
+ * error messages.
+ *
+ * <h2>Example usage:</h2>
+ * <pre>
+ * {@code
+ * int slot = getInt( args, 0 );
+ * int amount = optInt( args, 1, 64 );
+ * }
+ * </pre>
+ */
+public final class ArgumentHelper
+{
+    private ArgumentHelper()
+    {
+    }
+
+    /**
+     * Get a string representation of the given value's type.
+     *
+     * @param value The value whose type we are trying to compute.
+     * @return A string representation of the given value's type, in a similar format to that provided by Lua's
+     * {@code type} function.
+     */
+    @Nonnull
+    public static String getType( @Nullable Object value )
+    {
+        if( value == null ) return "nil";
+        if( value instanceof String ) return "string";
+        if( value instanceof Boolean ) return "boolean";
+        if( value instanceof Number ) return "number";
+        if( value instanceof Map ) return "table";
+        return "userdata";
+    }
+
+    /**
+     * Construct a "bad argument" exception, from an expected type and the actual value provided.
+     *
+     * @param index    The argument number, starting from 0.
+     * @param expected The expected type for this argument.
+     * @param actual   The actual value provided for this argument.
+     * @return The constructed exception, which should be thrown immediately.
+     */
+    @Nonnull
+    public static LuaException badArgumentOf( int index, @Nonnull String expected, @Nullable Object actual )
+    {
+        return badArgument( index, expected, getType( actual ) );
+    }
+
+    /**
+     * Construct a "bad argument" exception, from an expected and actual type.
+     *
+     * @param index    The argument number, starting from 0.
+     * @param expected The expected type for this argument.
+     * @param actual   The provided type for this argument.
+     * @return The constructed exception, which should be thrown immediately.
+     */
+    @Nonnull
+    public static LuaException badArgument( int index, @Nonnull String expected, @Nonnull String actual )
+    {
+        return new LuaException( "bad argument #" + (index + 1) + " (" + expected + " expected, got " + actual + ")" );
+    }
+
+    /**
+     * Get an argument as a double.
+     *
+     * @param args  The arguments to extract from.
+     * @param index The index into the argument array to read from.
+     * @return The argument's value.
+     * @throws LuaException If the value is not a number.
+     * @see #getFiniteDouble(Object[], int) if you require this to be finite (i.e. not infinite or NaN).
+     */
+    public static double getDouble( @Nonnull Object[] args, int index ) throws LuaException
+    {
+        if( index >= args.length ) throw badArgument( index, "number", "nil" );
+        Object value = args[index];
+        if( !(value instanceof Number) ) throw badArgumentOf( index, "number", value );
+        return ((Number) value).doubleValue();
+    }
+
+    /**
+     * Get an argument as an integer.
+     *
+     * @param args  The arguments to extract from.
+     * @param index The index into the argument array to read from.
+     * @return The argument's value.
+     * @throws LuaException If the value is not an integer.
+     */
+    public static int getInt( @Nonnull Object[] args, int index ) throws LuaException
+    {
+        return (int) getLong( args, index );
+    }
+
+    /**
+     * Get an argument as a long.
+     *
+     * @param args  The arguments to extract from.
+     * @param index The index into the argument array to read from.
+     * @return The argument's value.
+     * @throws LuaException If the value is not a long.
+     */
+    public static long getLong( @Nonnull Object[] args, int index ) throws LuaException
+    {
+        if( index >= args.length ) throw badArgument( index, "number", "nil" );
+        Object value = args[index];
+        if( !(value instanceof Number) ) throw badArgumentOf( index, "number", value );
+        return checkFinite( index, (Number) value ).longValue();
+    }
+
+    /**
+     * Get an argument as a finite number (not infinite or NaN).
+     *
+     * @param args  The arguments to extract from.
+     * @param index The index into the argument array to read from.
+     * @return The argument's value.
+     * @throws LuaException If the value is not finite.
+     */
+    public static double getFiniteDouble( @Nonnull Object[] args, int index ) throws LuaException
+    {
+        return checkFinite( index, getDouble( args, index ) );
+    }
+
+    /**
+     * Get an argument as a boolean.
+     *
+     * @param args  The arguments to extract from.
+     * @param index The index into the argument array to read from.
+     * @return The argument's value.
+     * @throws LuaException If the value is not a boolean.
+     */
+    public static boolean getBoolean( @Nonnull Object[] args, int index ) throws LuaException
+    {
+        if( index >= args.length ) throw badArgument( index, "boolean", "nil" );
+        Object value = args[index];
+        if( !(value instanceof Boolean) ) throw badArgumentOf( index, "boolean", value );
+        return (Boolean) value;
+    }
+
+    /**
+     * Get an argument as a string.
+     *
+     * @param args  The arguments to extract from.
+     * @param index The index into the argument array to read from.
+     * @return The argument's value.
+     * @throws LuaException If the value is not a string.
+     */
+    @Nonnull
+    public static String getString( @Nonnull Object[] args, int index ) throws LuaException
+    {
+        if( index >= args.length ) throw badArgument( index, "string", "nil" );
+        Object value = args[index];
+        if( !(value instanceof String) ) throw badArgumentOf( index, "string", value );
+        return (String) value;
+    }
+
+    /**
+     * Get an argument as a table.
+     *
+     * @param args  The arguments to extract from.
+     * @param index The index into the argument array to read from.
+     * @return The argument's value.
+     * @throws LuaException If the value is not a table.
+     */
+    @Nonnull
+    public static Map<?, ?> getTable( @Nonnull Object[] args, int index ) throws LuaException
+    {
+        if( index >= args.length ) throw badArgument( index, "table", "nil" );
+        Object value = args[index];
+        if( !(value instanceof Map) ) throw badArgumentOf( index, "table", value );
+        return (Map<?, ?>) value;
+    }
+
+    /**
+     * Get an argument as a double.
+     *
+     * @param args  The arguments to extract from.
+     * @param index The index into the argument array to read from.
+     * @param def   The default value, if this argument is not given.
+     * @return The argument's value, or {@code def} if none was provided.
+     * @throws LuaException If the value is not a number.
+     */
+    public static double optDouble( @Nonnull Object[] args, int index, double def ) throws LuaException
+    {
+        Object value = index < args.length ? args[index] : null;
+        if( value == null ) return def;
+        if( !(value instanceof Number) ) throw badArgumentOf( index, "number", value );
+        return ((Number) value).doubleValue();
+    }
+
+    /**
+     * Get an argument as an int.
+     *
+     * @param args  The arguments to extract from.
+     * @param index The index into the argument array to read from.
+     * @param def   The default value, if this argument is not given.
+     * @return The argument's value, or {@code def} if none was provided.
+     * @throws LuaException If the value is not a number.
+     */
+    public static int optInt( @Nonnull Object[] args, int index, int def ) throws LuaException
+    {
+        return (int) optLong( args, index, def );
+    }
+
+    /**
+     * Get an argument as a long.
+     *
+     * @param args  The arguments to extract from.
+     * @param index The index into the argument array to read from.
+     * @param def   The default value, if this argument is not given.
+     * @return The argument's value, or {@code def} if none was provided.
+     * @throws LuaException If the value is not a number.
+     */
+    public static long optLong( @Nonnull Object[] args, int index, long def ) throws LuaException
+    {
+        Object value = index < args.length ? args[index] : null;
+        if( value == null ) return def;
+        if( !(value instanceof Number) ) throw badArgumentOf( index, "number", value );
+        return checkFinite( index, (Number) value ).longValue();
+    }
+
+    /**
+     * Get an argument as a finite number (not infinite or NaN).
+     *
+     * @param args  The arguments to extract from.
+     * @param index The index into the argument array to read from.
+     * @param def   The default value, if this argument is not given.
+     * @return The argument's value, or {@code def} if none was provided.
+     * @throws LuaException If the value is not finite.
+     */
+    public static double optFiniteDouble( @Nonnull Object[] args, int index, double def ) throws LuaException
+    {
+        return checkFinite( index, optDouble( args, index, def ) );
+    }
+
+    /**
+     * Get an argument as a boolean.
+     *
+     * @param args  The arguments to extract from.
+     * @param index The index into the argument array to read from.
+     * @param def   The default value, if this argument is not given.
+     * @return The argument's value, or {@code def} if none was provided.
+     * @throws LuaException If the value is not a boolean.
+     */
+    public static boolean optBoolean( @Nonnull Object[] args, int index, boolean def ) throws LuaException
+    {
+        Object value = index < args.length ? args[index] : null;
+        if( value == null ) return def;
+        if( !(value instanceof Boolean) ) throw badArgumentOf( index, "boolean", value );
+        return (Boolean) value;
+    }
+
+    /**
+     * Get an argument as a string.
+     *
+     * @param args  The arguments to extract from.
+     * @param index The index into the argument array to read from.
+     * @param def   The default value, if this argument is not given.
+     * @return The argument's value, or {@code def} if none was provided.
+     * @throws LuaException If the value is not a string.
+     */
+    public static String optString( @Nonnull Object[] args, int index, String def ) throws LuaException
+    {
+        Object value = index < args.length ? args[index] : null;
+        if( value == null ) return def;
+        if( !(value instanceof String) ) throw badArgumentOf( index, "string", value );
+        return (String) value;
+    }
+
+    /**
+     * Get an argument as a table.
+     *
+     * @param args  The arguments to extract from.
+     * @param index The index into the argument array to read from.
+     * @param def   The default value, if this argument is not given.
+     * @return The argument's value, or {@code def} if none was provided.
+     * @throws LuaException If the value is not a table.
+     */
+    public static Map<?, ?> optTable( @Nonnull Object[] args, int index, Map<Object, Object> def ) throws LuaException
+    {
+        Object value = index < args.length ? args[index] : null;
+        if( value == null ) return def;
+        if( !(value instanceof Map) ) throw badArgumentOf( index, "table", value );
+        return (Map<?, ?>) value;
+    }
+
+    private static Number checkFinite( int index, Number value ) throws LuaException
+    {
+        checkFinite( index, value.doubleValue() );
+        return value;
+    }
+
+    private static double checkFinite( int index, double value ) throws LuaException
+    {
+        if( !Double.isFinite( value ) ) throw badArgument( index, "number", getNumericType( value ) );
+        return value;
+    }
+
+    /**
+     * Returns a more detailed representation of this number's type. If this is finite, it will just return "number",
+     * otherwise it returns whether it is infinite or NaN.
+     *
+     * @param value The value to extract the type for.
+     * @return This value's numeric type.
+     */
+    @Nonnull
+    public static String getNumericType( double value )
+    {
+        if( Double.isNaN( value ) ) return "nan";
+        if( value == Double.POSITIVE_INFINITY ) return "inf";
+        if( value == Double.NEGATIVE_INFINITY ) return "-inf";
+        return "number";
+    }
+}

src/main/java/dan200/computercraft/api/lua/IComputerSystem.java

@@ -26,7 +26,7 @@ public interface IComputerSystem extends IComputerAccess
     IFileSystem getFileSystem();
 
     /**
-     * Get the label for this computer
+     * Get the label for this computer.
      *
      * @return This computer's label, or {@code null} if it is not set.
      */

src/main/java/dan200/computercraft/api/peripheral/IPeripheral.java

@@ -6,6 +6,7 @@
 
 package dan200.computercraft.api.peripheral;
 
+import dan200.computercraft.api.lua.ArgumentHelper;
 import dan200.computercraft.api.lua.ILuaContext;
 import dan200.computercraft.api.lua.LuaException;
 
@@ -58,9 +59,11 @@ public interface IPeripheral
      *                  Lua values of type "table" will be represented by Object type Map.<br>
      *                  Lua values of any other type will be represented by a null object.<br>
      *                  This array will be empty if no arguments are passed.
+     *
+     *                  It is recommended you use {@link ArgumentHelper} in order to validate and process arguments.
      * @return An array of objects, representing values you wish to return to the lua program. Integers, Doubles, Floats,
-     * Strings, Booleans, Maps and ILuaObject and null be converted to their corresponding lua type. All other types
-     * will be converted to nil.
+     * Strings, Booleans, Maps, ILuaObject and null be converted to their corresponding lua type. All other types will
+     * be converted to nil.
      *
      * You may return null to indicate no values should be returned.
      * @throws LuaException         If you throw any exception from this function, a lua error will be raised with the
@@ -70,6 +73,7 @@ public interface IPeripheral
      *                              InterruptedException will be thrown. This exception must not be caught or
      *                              intercepted, or the computer will leak memory and end up in a broken state.
      * @see #getMethodNames
+     * @see ArgumentHelper
      */
     @Nullable
     Object[] callMethod( @Nonnull IComputerAccess computer, @Nonnull ILuaContext context, int method, @Nonnull Object[] arguments ) throws LuaException, InterruptedException;

src/main/java/dan200/computercraft/api/peripheral/IWorkMonitor.java

@@ -1,9 +1,8 @@
 /*
- * This file is part of ComputerCraft - http://www.computercraft.info
- * Copyright Daniel Ratcliffe, 2011-2019. Do not distribute without permission.
- * Send enquiries to dratcliffe@gmail.com
+ * This file is part of the public ComputerCraft API - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2019. This API may be redistributed unmodified and in full only.
+ * For help using the API, and posting your mods, visit the forums at computercraft.info.
  */
-
 package dan200.computercraft.api.peripheral;
 
 import javax.annotation.Nonnull;

src/main/java/dan200/computercraft/api/pocket/AbstractPocketUpgrade.java

@@ -1,9 +1,8 @@
 /*
- * This file is part of ComputerCraft - http://www.computercraft.info
- * Copyright Daniel Ratcliffe, 2011-2019. Do not distribute without permission.
- * Send enquiries to dratcliffe@gmail.com
+ * This file is part of the public ComputerCraft API - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2019. This API may be redistributed unmodified and in full only.
+ * For help using the API, and posting your mods, visit the forums at computercraft.info.
  */
-
 package dan200.computercraft.api.pocket;
 
 import net.minecraft.item.ItemStack;

src/main/java/dan200/computercraft/api/pocket/IPocketAccess.java

@@ -16,7 +16,7 @@ import javax.annotation.Nullable;
 import java.util.Map;
 
 /**
- * Wrapper class for pocket computers
+ * Wrapper class for pocket computers.
  */
 public interface IPocketAccess
 {

src/main/java/dan200/computercraft/api/turtle/ITurtleAccess.java

@@ -145,7 +145,9 @@ public interface ITurtleAccess
     GameProfile getOwningPlayer();
 
     /**
-     * Get the inventory of this turtle
+     * Get the inventory of this turtle.
+     *
+     * Note: this inventory should only be accessed and modified on the server thread.
      *
      * @return This turtle's inventory
      * @see #getItemHandler()
@@ -156,6 +158,8 @@ public interface ITurtleAccess
     /**
      * Get the inventory of this turtle as an {@link IItemHandlerModifiable}.
      *
+     * Note: this inventory should only be accessed and modified on the server thread.
+     *
      * @return This turtle's inventory
      * @see #getInventory()
      * @see IItemHandlerModifiable

src/main/java/dan200/computercraft/api/turtle/ITurtleUpgrade.java

@@ -109,8 +109,8 @@ public interface ITurtleUpgrade
      * Will only be called for Tool turtle. Called when turtle.dig() or turtle.attack() is called
      * by the turtle, and the tool is required to do some work.
      *
-     * Conforming implementations should fire {@link BlockEvent.BreakEvent} and {@link TurtleBlockEvent.Dig}for digging,
-     * {@link AttackEntityEvent} and {@link TurtleAttackEvent} for attacking.
+     * Conforming implementations should fire {@link BlockEvent.BreakEvent} and {@link TurtleBlockEvent.Dig} for
+     * digging, {@link AttackEntityEvent} and {@link TurtleAttackEvent} for attacking.
      *
      * @param turtle    Access to the turtle that the tool resides on.
      * @param side      Which side of the turtle (left or right) the tool resides on.

src/main/java/dan200/computercraft/api/turtle/TurtleSide.java

@@ -12,12 +12,12 @@ package dan200.computercraft.api.turtle;
 public enum TurtleSide
 {
     /**
-     * The turtle's left side (where the pickaxe usually is on a Wireless Mining Turtle)
+     * The turtle's left side (where the pickaxe usually is on a Wireless Mining Turtle).
      */
     Left,
 
     /**
-     * The turtle's right side (where the modem usually is on a Wireless Mining Turtle)
+     * The turtle's right side (where the modem usually is on a Wireless Mining Turtle).
      */
     Right,
 }

src/main/java/dan200/computercraft/api/turtle/TurtleVerb.java

@@ -18,12 +18,12 @@ import net.minecraft.util.EnumFacing;
 public enum TurtleVerb
 {
     /**
-     * The turtle called {@code turtle.dig()}, {@code turtle.digUp()} or {@code turtle.digDown()}
+     * The turtle called {@code turtle.dig()}, {@code turtle.digUp()} or {@code turtle.digDown()}.
      */
     Dig,
 
     /**
-     * The turtle called {@code turtle.attack()}, {@code turtle.attackUp()} or {@code turtle.attackDown()}
+     * The turtle called {@code turtle.attack()}, {@code turtle.attackUp()} or {@code turtle.attackDown()}.
      */
     Attack,
 }

src/main/java/dan200/computercraft/api/turtle/event/TurtleAction.java

@@ -71,7 +71,7 @@ public enum TurtleAction
     EQUIP,
 
     /**
-     * Inspect a block in world
+     * Inspect a block in world.
      *
      * @see TurtleBlockEvent.Inspect
      */

src/main/java/dan200/computercraft/api/turtle/event/TurtleBlockEvent.java

@@ -112,7 +112,7 @@ public abstract class TurtleBlockEvent extends TurtlePlayerEvent
         }
 
         /**
-         * Get the upgrade doing the digging
+         * Get the upgrade doing the digging.
          *
          * @return The upgrade doing the digging.
          */

src/main/java/dan200/computercraft/api/turtle/event/TurtleInspectItemEvent.java

@@ -1,9 +1,8 @@
 /*
- * This file is part of ComputerCraft - http://www.computercraft.info
- * Copyright Daniel Ratcliffe, 2011-2019. Do not distribute without permission.
- * Send enquiries to dratcliffe@gmail.com
+ * This file is part of the public ComputerCraft API - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2019. This API may be redistributed unmodified and in full only.
+ * For help using the API, and posting your mods, visit the forums at computercraft.info.
  */
-
 package dan200.computercraft.api.turtle.event;
 
 import dan200.computercraft.api.lua.ILuaContext;

src/main/java/dan200/computercraft/api/turtle/event/TurtleInventoryEvent.java

@@ -31,7 +31,7 @@ public abstract class TurtleInventoryEvent extends TurtleBlockEvent
     }
 
     /**
-     * Get the inventory being interacted with
+     * Get the inventory being interacted with.
      *
      * @return The inventory being interacted with, {@code null} if the item will be dropped to/sucked from the world.
      */

src/main/java/dan200/computercraft/api/turtle/event/TurtleRefuelEvent.java

@@ -1,9 +1,8 @@
 /*
- * This file is part of ComputerCraft - http://www.computercraft.info
- * Copyright Daniel Ratcliffe, 2011-2019. Do not distribute without permission.
- * Send enquiries to dratcliffe@gmail.com
+ * This file is part of the public ComputerCraft API - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2019. This API may be redistributed unmodified and in full only.
+ * For help using the API, and posting your mods, visit the forums at computercraft.info.
  */
-
 package dan200.computercraft.api.turtle.event;
 
 import dan200.computercraft.api.turtle.ITurtleAccess;

src/main/java/dan200/computercraft/client/gui/GuiComputer.java

@@ -24,9 +24,10 @@ import java.io.IOException;
 
 public class GuiComputer extends GuiContainer
 {
-    private static final ResourceLocation BACKGROUND = new ResourceLocation( "computercraft", "textures/gui/corners.png" );
-    private static final ResourceLocation BACKGROUND_ADVANCED = new ResourceLocation( "computercraft", "textures/gui/corners_advanced.png" );
-    private static final ResourceLocation BACKGROUND_COMMAND = new ResourceLocation( "computercraft", "textures/gui/corners_command.png" );
+    public static final ResourceLocation BACKGROUND_NORMAL = new ResourceLocation( ComputerCraft.MOD_ID, "textures/gui/corners.png" );
+    public static final ResourceLocation BACKGROUND_ADVANCED = new ResourceLocation( ComputerCraft.MOD_ID, "textures/gui/corners_advanced.png" );
+    public static final ResourceLocation BACKGROUND_COMMAND = new ResourceLocation( ComputerCraft.MOD_ID, "textures/gui/corners_command.png" );
+    public static final ResourceLocation BACKGROUND_COLOUR = new ResourceLocation( ComputerCraft.MOD_ID, "textures/gui/corners_colour.png" );
 
     private final ComputerFamily m_family;
     private final ClientComputer m_computer;
@@ -158,7 +159,7 @@ public class GuiComputer extends GuiContainer
         {
             case Normal:
             default:
-                mc.getTextureManager().bindTexture( BACKGROUND );
+                mc.getTextureManager().bindTexture( BACKGROUND_NORMAL );
                 break;
             case Advanced:
                 mc.getTextureManager().bindTexture( BACKGROUND_ADVANCED );
@@ -169,12 +170,12 @@ public class GuiComputer extends GuiContainer
         }
 
         drawTexturedModalRect( startX - 12, startY - 12, 12, 28, 12, 12 );
-        drawTexturedModalRect( startX - 12, endY, 12, 40, 12, 16 );
+        drawTexturedModalRect( startX - 12, endY, 12, 40, 12, 12 );
         drawTexturedModalRect( endX, startY - 12, 24, 28, 12, 12 );
-        drawTexturedModalRect( endX, endY, 24, 40, 12, 16 );
+        drawTexturedModalRect( endX, endY, 24, 40, 12, 12 );
 
         drawTexturedModalRect( startX, startY - 12, 0, 0, endX - startX, 12 );
-        drawTexturedModalRect( startX, endY, 0, 12, endX - startX, 16 );
+        drawTexturedModalRect( startX, endY, 0, 12, endX - startX, 12 );
 
         drawTexturedModalRect( startX - 12, startY, 0, 28, 12, endY - startY );
         drawTexturedModalRect( endX, startY, 36, 28, 12, endY - startY );

src/main/java/dan200/computercraft/client/gui/GuiTurtle.java

@@ -120,7 +120,7 @@ public class GuiTurtle extends GuiContainer
             int slotX = slot % 4;
             int slotY = slot / 4;
             mc.getTextureManager().bindTexture( advanced ? BACKGROUND_ADVANCED : BACKGROUND_NORMAL );
-            drawTexturedModalRect( guiLeft + m_container.m_turtleInvStartX - 2 + slotX * 18, guiTop + m_container.m_playerInvStartY - 2 + slotY * 18, 0, 217, 24, 24 );
+            drawTexturedModalRect( guiLeft + m_container.turtleInvStartX - 2 + slotX * 18, guiTop + m_container.playerInvStartY - 2 + slotY * 18, 0, 217, 24, 24 );
         }
     }
 

src/main/java/dan200/computercraft/client/render/CableHighlightRenderer.java

@@ -29,13 +29,13 @@ import net.minecraftforge.fml.relauncher.Side;
 import org.lwjgl.opengl.GL11;
 
 @Mod.EventBusSubscriber( modid = ComputerCraft.MOD_ID, value = Side.CLIENT )
-public final class RenderOverlayCable
+public final class CableHighlightRenderer
 {
     private static final float EXPAND = 0.002f;
     private static final double MIN = CableBounds.MIN - EXPAND;
     private static final double MAX = CableBounds.MAX + EXPAND;
 
-    private RenderOverlayCable()
+    private CableHighlightRenderer()
     {
     }
 

src/main/java/dan200/computercraft/client/render/ItemMapLikeRenderer.java

@@ -18,7 +18,7 @@ import net.minecraft.util.math.MathHelper;
 public abstract class ItemMapLikeRenderer
 {
     /**
-     * The main rendering method for the item
+     * The main rendering method for the item.
      *
      * @param stack The stack to render
      * @see ItemRenderer#renderMapFirstPerson(ItemStack)
@@ -87,7 +87,7 @@ public abstract class ItemMapLikeRenderer
     }
 
     /**
-     * Render an item in the middle of the screen
+     * Render an item in the middle of the screen.
      *
      * @param pitch         The pitch of the player
      * @param equipProgress The equip progress of this item

src/main/java/dan200/computercraft/client/render/ItemPocketRenderer.java

@@ -12,32 +12,35 @@ import dan200.computercraft.client.gui.FixedWidthFontRenderer;
 import dan200.computercraft.core.terminal.Terminal;
 import dan200.computercraft.core.terminal.TextBuffer;
 import dan200.computercraft.shared.computer.core.ClientComputer;
+import dan200.computercraft.shared.computer.core.ComputerFamily;
 import dan200.computercraft.shared.pocket.items.ItemPocketComputer;
+import dan200.computercraft.shared.util.Colour;
 import dan200.computercraft.shared.util.Palette;
 import net.minecraft.client.Minecraft;
+import net.minecraft.client.renderer.BufferBuilder;
 import net.minecraft.client.renderer.GlStateManager;
-import net.minecraft.client.renderer.RenderItem;
-import net.minecraft.client.renderer.block.model.IBakedModel;
-import net.minecraft.client.renderer.block.model.ItemCameraTransforms;
-import net.minecraft.client.renderer.texture.TextureManager;
-import net.minecraft.client.renderer.texture.TextureMap;
+import net.minecraft.client.renderer.Tessellator;
+import net.minecraft.client.renderer.vertex.DefaultVertexFormats;
 import net.minecraft.item.ItemStack;
-import net.minecraftforge.client.ForgeHooksClient;
 import net.minecraftforge.client.event.RenderSpecificHandEvent;
 import net.minecraftforge.fml.common.Mod;
 import net.minecraftforge.fml.common.eventhandler.SubscribeEvent;
 import net.minecraftforge.fml.relauncher.Side;
 import org.lwjgl.opengl.GL11;
 
-import static dan200.computercraft.client.gui.FixedWidthFontRenderer.FONT_HEIGHT;
-import static dan200.computercraft.client.gui.FixedWidthFontRenderer.FONT_WIDTH;
+import static dan200.computercraft.client.gui.FixedWidthFontRenderer.*;
+import static dan200.computercraft.client.gui.GuiComputer.*;
 
 /**
- * Emulates map rendering for pocket computers
+ * Emulates map rendering for pocket computers.
  */
 @Mod.EventBusSubscriber( modid = ComputerCraft.MOD_ID, value = Side.CLIENT )
 public final class ItemPocketRenderer extends ItemMapLikeRenderer
 {
+    private static final int MARGIN = 2;
+    private static final int FRAME = 12;
+    private static final int LIGHT_HEIGHT = 8;
+
     private static final ItemPocketRenderer INSTANCE = new ItemPocketRenderer();
 
     private ItemPocketRenderer()
@@ -57,115 +60,194 @@ public final class ItemPocketRenderer extends ItemMapLikeRenderer
     @Override
     protected void renderItem( ItemStack stack )
     {
+        ClientComputer computer = ItemPocketComputer.createClientComputer( stack );
+        Terminal terminal = computer == null ? null : computer.getTerminal();
+
+        int termWidth, termHeight;
+        if( terminal == null )
+        {
+            termWidth = ComputerCraft.terminalWidth_pocketComputer;
+            termHeight = ComputerCraft.terminalHeight_pocketComputer;
+        }
+        else
+        {
+            termWidth = terminal.getWidth();
+            termHeight = terminal.getHeight();
+        }
+
+        int width = termWidth * FONT_WIDTH + MARGIN * 2;
+        int height = termHeight * FONT_HEIGHT + MARGIN * 2;
+
         // Setup various transformations. Note that these are partially adapted from the corresponding method
         // in ItemRenderer
+        GlStateManager.pushMatrix();
+
         GlStateManager.disableLighting();
+        GlStateManager.disableDepth();
 
         GlStateManager.rotate( 180f, 0f, 1f, 0f );
         GlStateManager.rotate( 180f, 0f, 0f, 1f );
         GlStateManager.scale( 0.5, 0.5, 0.5 );
 
-        ClientComputer computer = ItemPocketComputer.createClientComputer( stack );
+        double scale = 0.75 / Math.max( width + FRAME * 2, height + FRAME * 2 + LIGHT_HEIGHT );
+        GlStateManager.scale( scale, scale, 0 );
+        GlStateManager.translate( -0.5 * width, -0.5 * height, 0 );
 
+        // Render the main frame
+        ComputerFamily family = ComputerCraft.Items.pocketComputer.getFamily( stack );
+        int frameColour = ComputerCraft.Items.pocketComputer.getColour( stack );
+        renderFrame( family, frameColour, width, height );
+
+        // Render the light
+        int lightColour = ItemPocketComputer.getLightState( stack );
+        if( lightColour == -1 ) lightColour = Colour.Black.getHex();
+        renderLight( lightColour, width, height );
+
+        if( computer != null && terminal != null )
         {
-            // First render the background item. We use the item's model rather than a direct texture as this ensures
-            // we display the pocket light and other such decorations.
-            GlStateManager.pushMatrix();
+            // If we've a computer and terminal then attempt to render it.
+            renderTerminal( terminal, !computer.isColour(), width, height );
+        }
+        else
+        {
+            // Otherwise render a plain background
+            Minecraft.getMinecraft().getTextureManager().bindTexture( BACKGROUND );
 
-            GlStateManager.scale( 1.0f, -1.0f, 1.0f );
+            Tessellator tessellator = Tessellator.getInstance();
+            BufferBuilder buffer = tessellator.getBuffer();
 
-            Minecraft minecraft = Minecraft.getMinecraft();
-            TextureManager textureManager = minecraft.getTextureManager();
-            RenderItem renderItem = minecraft.getRenderItem();
-
-            // Copy of RenderItem#renderItemModelIntoGUI but without the translation or scaling
-            textureManager.bindTexture( TextureMap.LOCATION_BLOCKS_TEXTURE );
-            textureManager.getTexture( TextureMap.LOCATION_BLOCKS_TEXTURE ).setBlurMipmap( false, false );
-
-            GlStateManager.enableRescaleNormal();
-            GlStateManager.enableAlpha();
-            GlStateManager.alphaFunc( GL11.GL_GREATER, 0.1F );
-            GlStateManager.enableBlend();
-            GlStateManager.blendFunc( GlStateManager.SourceFactor.SRC_ALPHA, GlStateManager.DestFactor.ONE_MINUS_SRC_ALPHA );
-            GlStateManager.color( 1.0F, 1.0F, 1.0F, 1.0F );
-
-            IBakedModel baked = renderItem.getItemModelWithOverrides( stack, null, null );
-            baked = ForgeHooksClient.handleCameraTransforms( baked, ItemCameraTransforms.TransformType.GUI, false );
-            renderItem.renderItem( stack, baked );
-
-            GlStateManager.disableAlpha();
-            GlStateManager.disableRescaleNormal();
-
-            GlStateManager.popMatrix();
+            Colour black = Colour.Black;
+            buffer.begin( GL11.GL_QUADS, DefaultVertexFormats.POSITION );
+            renderTexture( buffer, 0, 0, 0, 0, width, height, black.getR(), black.getG(), black.getB() );
+            tessellator.draw();
         }
 
-        // If we've a computer and terminal then attempt to render it.
-        if( computer != null )
+        GlStateManager.enableDepth();
+        GlStateManager.enableLighting();
+        GlStateManager.popMatrix();
+    }
+
+    private static void renderFrame( ComputerFamily family, int colour, int width, int height )
+    {
+
+        Minecraft.getMinecraft().getTextureManager().bindTexture( colour != -1
+            ? BACKGROUND_COLOUR
+            : family == ComputerFamily.Normal ? BACKGROUND_NORMAL : BACKGROUND_ADVANCED
+        );
+
+        float r = ((colour >>> 16) & 0xFF) / 255.0f;
+        float g = ((colour >>> 8) & 0xFF) / 255.0f;
+        float b = (colour & 0xFF) / 255.0f;
+
+        Tessellator tessellator = Tessellator.getInstance();
+        BufferBuilder buffer = tessellator.getBuffer();
+        buffer.begin( GL11.GL_QUADS, DefaultVertexFormats.POSITION_TEX_COLOR );
+
+        // Top left, middle, right
+        renderTexture( buffer, -FRAME, -FRAME, 12, 28, FRAME, FRAME, r, g, b );
+        renderTexture( buffer, 0, -FRAME, 0, 0, width, FRAME, r, g, b );
+        renderTexture( buffer, width, -FRAME, 24, 28, FRAME, FRAME, r, g, b );
+
+        // Left and bright border
+        renderTexture( buffer, -FRAME, 0, 0, 28, FRAME, height, r, g, b );
+        renderTexture( buffer, width, 0, 36, 28, FRAME, height, r, g, b );
+
+        // Bottom left, middle, right. We do this in three portions: the top inner corners, an extended region for
+        // lights, and then the bottom outer corners.
+        renderTexture( buffer, -FRAME, height, 12, 40, FRAME, FRAME / 2, r, g, b );
+        renderTexture( buffer, 0, height, 0, 12, width, FRAME / 2, r, g, b );
+        renderTexture( buffer, width, height, 24, 40, FRAME, FRAME / 2, r, g, b );
+
+        renderTexture( buffer, -FRAME, height + FRAME / 2, 12, 44, FRAME, LIGHT_HEIGHT, FRAME, 4, r, g, b );
+        renderTexture( buffer, 0, height + FRAME / 2, 0, 16, width, LIGHT_HEIGHT, FRAME, 4, r, g, b );
+        renderTexture( buffer, width, height + FRAME / 2, 24, 44, FRAME, LIGHT_HEIGHT, FRAME, 4, r, g, b );
+
+        renderTexture( buffer, -FRAME, height + LIGHT_HEIGHT + FRAME / 2, 12, 40 + FRAME / 2, FRAME, FRAME / 2, r, g, b );
+        renderTexture( buffer, 0, height + LIGHT_HEIGHT + FRAME / 2, 0, 12 + FRAME / 2, width, FRAME / 2, r, g, b );
+        renderTexture( buffer, width, height + LIGHT_HEIGHT + FRAME / 2, 24, 40 + FRAME / 2, FRAME, FRAME / 2, r, g, b );
+
+        tessellator.draw();
+    }
+
+    private static void renderLight( int colour, int width, int height )
+    {
+        GlStateManager.enableBlend();
+        GlStateManager.disableTexture2D();
+
+        float r = ((colour >>> 16) & 0xFF) / 255.0f;
+        float g = ((colour >>> 8) & 0xFF) / 255.0f;
+        float b = (colour & 0xFF) / 255.0f;
+
+        Tessellator tessellator = Tessellator.getInstance();
+        BufferBuilder buffer = tessellator.getBuffer();
+        buffer.begin( GL11.GL_QUADS, DefaultVertexFormats.POSITION_COLOR );
+        buffer.pos( width - LIGHT_HEIGHT * 2, height + LIGHT_HEIGHT + FRAME / 2.0f, 0.0D ).color( r, g, b, 1.0f ).endVertex();
+        buffer.pos( width, height + LIGHT_HEIGHT + FRAME / 2.0f, 0.0D ).color( r, g, b, 1.0f ).endVertex();
+        buffer.pos( width, height + FRAME / 2.0f, 0.0D ).color( r, g, b, 1.0f ).endVertex();
+        buffer.pos( width - LIGHT_HEIGHT * 2, height + FRAME / 2.0f, 0.0D ).color( r, g, b, 1.0f ).endVertex();
+
+        tessellator.draw();
+        GlStateManager.enableTexture2D();
+    }
+
+    private static void renderTerminal( Terminal terminal, boolean greyscale, int width, int height )
+    {
+        synchronized( terminal )
         {
-            Terminal terminal = computer.getTerminal();
-            if( terminal != null )
+            int termWidth = terminal.getWidth();
+            int termHeight = terminal.getHeight();
+
+            FixedWidthFontRenderer fontRenderer = FixedWidthFontRenderer.instance();
+            Palette palette = terminal.getPalette();
+
+            // Render top/bottom borders
+            TextBuffer emptyLine = new TextBuffer( ' ', termWidth );
+            fontRenderer.drawString(
+                emptyLine, MARGIN, 0,
+                terminal.getTextColourLine( 0 ), terminal.getBackgroundColourLine( 0 ), MARGIN, MARGIN, greyscale, palette
+            );
+            fontRenderer.drawString(
+                emptyLine, MARGIN, 2 * MARGIN + (termHeight - 1) * FixedWidthFontRenderer.FONT_HEIGHT,
+                terminal.getTextColourLine( termHeight - 1 ), terminal.getBackgroundColourLine( termHeight - 1 ), MARGIN, MARGIN, greyscale, palette
+            );
+
+            // Render the actual text
+            for( int line = 0; line < termWidth; line++ )
             {
-                synchronized( terminal )
-                {
-                    GlStateManager.pushMatrix();
-                    GlStateManager.disableDepth();
+                TextBuffer text = terminal.getLine( line );
+                TextBuffer colour = terminal.getTextColourLine( line );
+                TextBuffer backgroundColour = terminal.getBackgroundColourLine( line );
+                fontRenderer.drawString(
+                    text, MARGIN, MARGIN + line * FONT_HEIGHT,
+                    colour, backgroundColour, MARGIN, MARGIN, greyscale, palette
+                );
+            }
 
-                    // Reset the position to be at the top left corner of the pocket computer
-                    // Note we translate towards the screen slightly too.
-                    GlStateManager.translate( -8 / 16.0, -8 / 16.0, 0.5 / 16.0 );
-                    // Translate to the top left of the screen.
-                    GlStateManager.translate( 4 / 16.0, 3 / 16.0, 0 );
-
-                    // Work out the scaling required to resize the terminal in order to fit on the computer
-                    final int margin = 2;
-                    int tw = terminal.getWidth();
-                    int th = terminal.getHeight();
-                    int width = tw * FONT_WIDTH + margin * 2;
-                    int height = th * FONT_HEIGHT + margin * 2;
-                    int max = Math.max( height, width );
-
-                    // The grid is 8 * 8 wide, so we start with a base of 1/2 (8 / 16).
-                    double scale = 1.0 / 2.0 / max;
-                    GlStateManager.scale( scale, scale, scale );
-
-                    // The margin/start positions are determined in order for the terminal to be centred.
-                    int startX = (max - width) / 2 + margin;
-                    int startY = (max - height) / 2 + margin;
-
-                    FixedWidthFontRenderer fontRenderer = FixedWidthFontRenderer.instance();
-                    boolean greyscale = !computer.isColour();
-                    Palette palette = terminal.getPalette();
-
-                    // Render the actual text
-                    for( int line = 0; line < th; line++ )
-                    {
-                        TextBuffer text = terminal.getLine( line );
-                        TextBuffer colour = terminal.getTextColourLine( line );
-                        TextBuffer backgroundColour = terminal.getBackgroundColourLine( line );
-                        fontRenderer.drawString(
-                            text, startX, startY + line * FONT_HEIGHT,
-                            colour, backgroundColour, margin, margin, greyscale, palette
-                        );
-                    }
-
-                    // And render the cursor;
-                    int tx = terminal.getCursorX(), ty = terminal.getCursorY();
-                    if( terminal.getCursorBlink() && FrameInfo.getGlobalCursorBlink() &&
-                        tx >= 0 && ty >= 0 && tx < tw && ty < th )
-                    {
-                        TextBuffer cursorColour = new TextBuffer( "0123456789abcdef".charAt( terminal.getTextColour() ), 1 );
-                        fontRenderer.drawString(
-                            new TextBuffer( '_', 1 ), startX + FONT_WIDTH * tx, startY + FONT_HEIGHT * ty,
-                            cursorColour, null, 0, 0, greyscale, palette
-                        );
-                    }
-
-                    GlStateManager.enableDepth();
-                    GlStateManager.popMatrix();
-                }
+            // And render the cursor;
+            int tx = terminal.getCursorX(), ty = terminal.getCursorY();
+            if( terminal.getCursorBlink() && FrameInfo.getGlobalCursorBlink() &&
+                tx >= 0 && ty >= 0 && tx < termWidth && ty < termHeight )
+            {
+                TextBuffer cursorColour = new TextBuffer( "0123456789abcdef".charAt( terminal.getTextColour() ), 1 );
+                fontRenderer.drawString(
+                    new TextBuffer( '_', 1 ), MARGIN + FONT_WIDTH * tx, MARGIN + FONT_HEIGHT * ty,
+                    cursorColour, null, 0, 0, greyscale, palette
+                );
             }
         }
+    }
 
-        GlStateManager.enableLighting();
+    private static void renderTexture( BufferBuilder builder, int x, int y, int textureX, int textureY, int width, int height, float r, float g, float b )
+    {
+        renderTexture( builder, x, y, textureX, textureY, width, height, width, height, r, g, b );
+    }
+
+    private static void renderTexture( BufferBuilder builder, int x, int y, int textureX, int textureY, int width, int height, int textureWidth, int textureHeight, float r, float g, float b )
+    {
+        float scale = 1 / 255.0f;
+        builder.pos( x, y + height, 0 ).tex( textureX * scale, (textureY + textureHeight) * scale ).color( r, g, b, 1.0f ).endVertex();
+        builder.pos( x + width, y + height, 0 ).tex( (textureX + textureWidth) * scale, (textureY + textureHeight) * scale ).color( r, g, b, 1.0f ).endVertex();
+        builder.pos( x + width, y, 0 ).tex( (textureX + textureWidth) * scale, textureY * scale ).color( r, g, b, 1.0f ).endVertex();
+        builder.pos( x, y, 0 ).tex( textureX * scale, textureY * scale ).color( r, g, b, 1.0f ).endVertex();
     }
 }

src/main/java/dan200/computercraft/client/render/ItemPrintoutRenderer.java

@@ -23,7 +23,7 @@ import static dan200.computercraft.shared.media.items.ItemPrintout.LINES_PER_PAG
 import static dan200.computercraft.shared.media.items.ItemPrintout.LINE_MAX_LENGTH;
 
 /**
- * Emulates map and item-frame rendering for printouts
+ * Emulates map and item-frame rendering for printouts.
  */
 @Mod.EventBusSubscriber( modid = ComputerCraft.MOD_ID, value = Side.CLIENT )
 public final class ItemPrintoutRenderer extends ItemMapLikeRenderer

src/main/java/dan200/computercraft/client/render/ModelTransformer.java

@@ -94,7 +94,7 @@ public final class ModelTransformer
         private final Point3f[] before = new Point3f[4];
         private final Point3f[] after = new Point3f[4];
 
-        public NormalAwareTransformer( IVertexConsumer parent, Matrix4f positionMatrix, Matrix4f normalMatrix )
+        NormalAwareTransformer( IVertexConsumer parent, Matrix4f positionMatrix, Matrix4f normalMatrix )
         {
             super( parent );
             this.positionMatrix = positionMatrix;

src/main/java/dan200/computercraft/client/render/MonitorHighlightRenderer.java

@@ -0,0 +1,118 @@
+/*
+ * This file is part of ComputerCraft - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2019. Do not distribute without permission.
+ * Send enquiries to dratcliffe@gmail.com
+ */
+
+package dan200.computercraft.client.render;
+
+import dan200.computercraft.ComputerCraft;
+import dan200.computercraft.shared.peripheral.monitor.TileMonitor;
+import net.minecraft.client.renderer.BufferBuilder;
+import net.minecraft.client.renderer.GlStateManager;
+import net.minecraft.client.renderer.Tessellator;
+import net.minecraft.client.renderer.vertex.DefaultVertexFormats;
+import net.minecraft.entity.player.EntityPlayer;
+import net.minecraft.tileentity.TileEntity;
+import net.minecraft.util.EnumFacing;
+import net.minecraft.util.math.BlockPos;
+import net.minecraft.util.math.RayTraceResult;
+import net.minecraft.world.World;
+import net.minecraftforge.client.event.DrawBlockHighlightEvent;
+import net.minecraftforge.fml.common.Mod;
+import net.minecraftforge.fml.common.eventhandler.SubscribeEvent;
+import net.minecraftforge.fml.relauncher.Side;
+import org.lwjgl.opengl.GL11;
+
+import java.util.EnumSet;
+
+import static net.minecraft.util.EnumFacing.*;
+
+@Mod.EventBusSubscriber( modid = ComputerCraft.MOD_ID, value = Side.CLIENT )
+public final class MonitorHighlightRenderer
+{
+    private static final float EXPAND = 0.002f;
+
+    private MonitorHighlightRenderer()
+    {
+    }
+
+    @SubscribeEvent
+    public static void drawHighlight( DrawBlockHighlightEvent event )
+    {
+        if( event.getTarget().typeOfHit != RayTraceResult.Type.BLOCK || event.getPlayer().isSneaking() ) return;
+
+        World world = event.getPlayer().getEntityWorld();
+        BlockPos pos = event.getTarget().getBlockPos();
+
+        if( world.getBlockState( pos ).getBlock() != ComputerCraft.Blocks.peripheral ) return;
+
+        TileEntity tile = world.getTileEntity( pos );
+        if( !(tile instanceof TileMonitor) ) return;
+
+        TileMonitor monitor = (TileMonitor) tile;
+        event.setCanceled( true );
+
+        // Determine which sides are part of the external faces of the monitor, and so which need to be rendered.
+        EnumSet<EnumFacing> faces = EnumSet.allOf( EnumFacing.class );
+        EnumFacing front = monitor.getFront();
+        faces.remove( front );
+        if( monitor.getXIndex() != 0 ) faces.remove( monitor.getRight().getOpposite() );
+        if( monitor.getXIndex() != monitor.getWidth() - 1 ) faces.remove( monitor.getRight() );
+        if( monitor.getYIndex() != 0 ) faces.remove( monitor.getDown().getOpposite() );
+        if( monitor.getYIndex() != monitor.getHeight() - 1 ) faces.remove( monitor.getDown() );
+
+        GlStateManager.enableBlend();
+        GlStateManager.tryBlendFuncSeparate( GlStateManager.SourceFactor.SRC_ALPHA, GlStateManager.DestFactor.ONE_MINUS_SRC_ALPHA, GlStateManager.SourceFactor.ONE, GlStateManager.DestFactor.ZERO );
+        GL11.glLineWidth( 2.0F );
+        GlStateManager.disableTexture2D();
+        GlStateManager.depthMask( false );
+        GlStateManager.pushMatrix();
+
+        EntityPlayer player = event.getPlayer();
+        double x = player.lastTickPosX + (player.posX - player.lastTickPosX) * event.getPartialTicks();
+        double y = player.lastTickPosY + (player.posY - player.lastTickPosY) * event.getPartialTicks();
+        double z = player.lastTickPosZ + (player.posZ - player.lastTickPosZ) * event.getPartialTicks();
+
+        GlStateManager.translate( -x + pos.getX(), -y + pos.getY(), -z + pos.getZ() );
+
+        Tessellator tessellator = Tessellator.getInstance();
+        BufferBuilder buffer = tessellator.getBuffer();
+        buffer.begin( GL11.GL_LINES, DefaultVertexFormats.POSITION_COLOR );
+
+        // I wish I could think of a better way to do this
+        if( faces.contains( NORTH ) || faces.contains( WEST ) ) line( buffer, 0, 0, 0, UP );
+        if( faces.contains( SOUTH ) || faces.contains( WEST ) ) line( buffer, 0, 0, 1, UP );
+        if( faces.contains( NORTH ) || faces.contains( EAST ) ) line( buffer, 1, 0, 0, UP );
+        if( faces.contains( SOUTH ) || faces.contains( EAST ) ) line( buffer, 1, 0, 1, UP );
+        if( faces.contains( NORTH ) || faces.contains( DOWN ) ) line( buffer, 0, 0, 0, EAST );
+        if( faces.contains( SOUTH ) || faces.contains( DOWN ) ) line( buffer, 0, 0, 1, EAST );
+        if( faces.contains( NORTH ) || faces.contains( UP ) ) line( buffer, 0, 1, 0, EAST );
+        if( faces.contains( SOUTH ) || faces.contains( UP ) ) line( buffer, 0, 1, 1, EAST );
+        if( faces.contains( WEST ) || faces.contains( DOWN ) ) line( buffer, 0, 0, 0, SOUTH );
+        if( faces.contains( EAST ) || faces.contains( DOWN ) ) line( buffer, 1, 0, 0, SOUTH );
+        if( faces.contains( WEST ) || faces.contains( UP ) ) line( buffer, 0, 1, 0, SOUTH );
+        if( faces.contains( EAST ) || faces.contains( UP ) ) line( buffer, 1, 1, 0, SOUTH );
+
+        tessellator.draw();
+
+        GlStateManager.popMatrix();
+        GlStateManager.depthMask( true );
+        GlStateManager.enableTexture2D();
+        GlStateManager.disableBlend();
+    }
+
+    private static void line( BufferBuilder buffer, int x, int y, int z, EnumFacing direction )
+    {
+        double minX = x == 0 ? -EXPAND : 1 + EXPAND;
+        double minY = y == 0 ? -EXPAND : 1 + EXPAND;
+        double minZ = z == 0 ? -EXPAND : 1 + EXPAND;
+
+        buffer.pos( minX, minY, minZ ).color( 0, 0, 0, 0.4f ).endVertex();
+        buffer.pos(
+            minX + direction.getXOffset() * (1 + EXPAND * 2),
+            minY + direction.getYOffset() * (1 + EXPAND * 2),
+            minZ + direction.getZOffset() * (1 + EXPAND * 2)
+        ).color( 0, 0, 0, 0.4f ).endVertex();
+    }
+}

src/main/java/dan200/computercraft/client/render/PrintoutRenderer.java

@@ -28,32 +28,32 @@ public final class PrintoutRenderer
     private static final double BG_SIZE = 256.0;
 
     /**
-     * Width of a page
+     * Width of a page.
      */
     public static final int X_SIZE = 172;
 
     /**
-     * Height of a page
+     * Height of a page.
      */
     public static final int Y_SIZE = 209;
 
     /**
-     * Padding between the left and right of a page and the text
+     * Padding between the left and right of a page and the text.
      */
     public static final int X_TEXT_MARGIN = 13;
 
     /**
-     * Padding between the top and bottom of a page and the text
+     * Padding between the top and bottom of a page and the text.
      */
     public static final int Y_TEXT_MARGIN = 11;
 
     /**
-     * Width of the extra page texture
+     * Width of the extra page texture.
      */
     private static final int X_FOLD_SIZE = 12;
 
     /**
-     * Size of the leather cover
+     * Size of the leather cover.
      */
     public static final int COVER_SIZE = 12;
 

src/main/java/dan200/computercraft/client/render/TileEntityCableRenderer.java

@@ -97,6 +97,8 @@ public class TileEntityCableRenderer extends TileEntitySpecialRenderer<TileCable
     }
 
     /**
+     * Set up the state for rendering block-breaking progress.
+     *
      * @see RenderGlobal#preRenderDamagedBlocks()
      */
     private void preRenderDamagedBlocks()
@@ -115,6 +117,8 @@ public class TileEntityCableRenderer extends TileEntitySpecialRenderer<TileCable
     }
 
     /**
+     * Tear down the state for rendering block-breaking progress.
+     *
      * @see RenderGlobal#postRenderDamagedBlocks()
      */
     private void postRenderDamagedBlocks()

src/main/java/dan200/computercraft/core/apis/AddressPredicate.java

@@ -154,7 +154,7 @@ public class AddressPredicate
     }
 
     /**
-     * Determine whether the given address matches a series of patterns
+     * Determine whether the given address matches a series of patterns.
      *
      * @param address The address to check.
      * @return Whether it matches any of these patterns.

src/main/java/dan200/computercraft/core/apis/ApiFactories.java

@@ -6,13 +6,13 @@
 
 package dan200.computercraft.core.apis;
 
-import com.google.common.base.Preconditions;
 import dan200.computercraft.api.lua.ILuaAPIFactory;
 
 import javax.annotation.Nonnull;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.LinkedHashSet;
+import java.util.Objects;
 
 public final class ApiFactories
 {
@@ -25,7 +25,7 @@ public final class ApiFactories
 
     public static void register( @Nonnull ILuaAPIFactory factory )
     {
-        Preconditions.checkNotNull( factory, "provider cannot be null" );
+        Objects.requireNonNull( factory, "provider cannot be null" );
         factories.add( factory );
     }
 

src/main/java/dan200/computercraft/core/apis/ArgumentHelper.java

@@ -13,256 +13,106 @@ import javax.annotation.Nullable;
 import java.util.Map;
 
 /**
- * Various helpers for arguments
+ * A stub for any mods which depended on this version of the argument helper.
+ *
+ * @deprecated Use {@link dan200.computercraft.api.lua.ArgumentHelper}.
  */
+@Deprecated
 public final class ArgumentHelper
 {
     private ArgumentHelper()
     {
-        throw new IllegalStateException( "Cannot instantiate singleton " + getClass().getName() );
     }
 
     @Nonnull
     public static String getType( @Nullable Object type )
     {
-        if( type == null ) return "nil";
-        if( type instanceof String ) return "string";
-        if( type instanceof Boolean ) return "boolean";
-        if( type instanceof Number ) return "number";
-        if( type instanceof Map ) return "table";
-
-        Class<?> klass = type.getClass();
-        if( klass.isArray() )
-        {
-            StringBuilder name = new StringBuilder();
-            while( klass.isArray() )
-            {
-                name.append( "[]" );
-                klass = klass.getComponentType();
-            }
-            name.insert( 0, klass.getName() );
-            return name.toString();
-        }
-        else
-        {
-            return klass.getName();
-        }
+        return dan200.computercraft.api.lua.ArgumentHelper.getType( type );
     }
 
     @Nonnull
     public static LuaException badArgument( int index, @Nonnull String expected, @Nullable Object actual )
     {
-        return badArgument( index, expected, getType( actual ) );
+        return dan200.computercraft.api.lua.ArgumentHelper.badArgumentOf( index, expected, actual );
     }
 
     @Nonnull
     public static LuaException badArgument( int index, @Nonnull String expected, @Nonnull String actual )
     {
-        return new LuaException( "bad argument #" + (index + 1) + " (" + expected + " expected, got " + actual + ")" );
+        return dan200.computercraft.api.lua.ArgumentHelper.badArgument( index, expected, actual );
     }
 
     public static double getNumber( @Nonnull Object[] args, int index ) throws LuaException
     {
-        if( index >= args.length ) throw badArgument( index, "number", "nil" );
-        Object value = args[index];
-        if( value instanceof Number )
-        {
-            return ((Number) value).doubleValue();
-        }
-        else
-        {
-            throw badArgument( index, "number", value );
-        }
+        return dan200.computercraft.api.lua.ArgumentHelper.getDouble( args, index );
     }
 
     public static int getInt( @Nonnull Object[] args, int index ) throws LuaException
     {
-        return (int) getLong( args, index );
+        return dan200.computercraft.api.lua.ArgumentHelper.getInt( args, index );
     }
 
     public static long getLong( @Nonnull Object[] args, int index ) throws LuaException
     {
-        if( index >= args.length ) throw badArgument( index, "number", "nil" );
-        Object value = args[index];
-        if( value instanceof Number )
-        {
-            return checkReal( index, (Number) value ).longValue();
-        }
-        else
-        {
-            throw badArgument( index, "number", value );
-        }
+        return dan200.computercraft.api.lua.ArgumentHelper.getLong( args, index );
     }
 
     public static double getReal( @Nonnull Object[] args, int index ) throws LuaException
     {
-        return checkReal( index, getNumber( args, index ) );
+        return dan200.computercraft.api.lua.ArgumentHelper.getFiniteDouble( args, index );
     }
 
     public static boolean getBoolean( @Nonnull Object[] args, int index ) throws LuaException
     {
-        if( index >= args.length ) throw badArgument( index, "boolean", "nil" );
-        Object value = args[index];
-        if( value instanceof Boolean )
-        {
-            return (Boolean) value;
-        }
-        else
-        {
-            throw badArgument( index, "boolean", value );
-        }
+        return dan200.computercraft.api.lua.ArgumentHelper.getBoolean( args, index );
     }
 
     @Nonnull
     public static String getString( @Nonnull Object[] args, int index ) throws LuaException
     {
-        if( index >= args.length ) throw badArgument( index, "string", "nil" );
-        Object value = args[index];
-        if( value instanceof String )
-        {
-            return (String) value;
-        }
-        else
-        {
-            throw badArgument( index, "string", value );
-        }
+        return dan200.computercraft.api.lua.ArgumentHelper.getString( args, index );
     }
 
-    @SuppressWarnings( "unchecked" )
     @Nonnull
+    @SuppressWarnings( "unchecked" )
     public static Map<Object, Object> getTable( @Nonnull Object[] args, int index ) throws LuaException
     {
-        if( index >= args.length ) throw badArgument( index, "table", "nil" );
-        Object value = args[index];
-        if( value instanceof Map )
-        {
-            return (Map<Object, Object>) value;
-        }
-        else
-        {
-            throw badArgument( index, "table", value );
-        }
+        return (Map<Object, Object>) dan200.computercraft.api.lua.ArgumentHelper.getTable( args, index );
     }
 
     public static double optNumber( @Nonnull Object[] args, int index, double def ) throws LuaException
     {
-        Object value = index < args.length ? args[index] : null;
-        if( value == null )
-        {
-            return def;
-        }
-        else if( value instanceof Number )
-        {
-            return ((Number) value).doubleValue();
-        }
-        else
-        {
-            throw badArgument( index, "number", value );
-        }
+        return dan200.computercraft.api.lua.ArgumentHelper.optDouble( args, index, def );
     }
 
     public static int optInt( @Nonnull Object[] args, int index, int def ) throws LuaException
     {
-        return (int) optLong( args, index, def );
+        return dan200.computercraft.api.lua.ArgumentHelper.optInt( args, index, def );
     }
 
     public static long optLong( @Nonnull Object[] args, int index, long def ) throws LuaException
     {
-        Object value = index < args.length ? args[index] : null;
-        if( value == null )
-        {
-            return def;
-        }
-        else if( value instanceof Number )
-        {
-            return checkReal( index, (Number) value ).longValue();
-        }
-        else
-        {
-            throw badArgument( index, "number", value );
-        }
+        return dan200.computercraft.api.lua.ArgumentHelper.optLong( args, index, def );
     }
 
     public static double optReal( @Nonnull Object[] args, int index, double def ) throws LuaException
     {
-        return checkReal( index, optNumber( args, index, def ) );
+        return dan200.computercraft.api.lua.ArgumentHelper.optFiniteDouble( args, index, def );
     }
 
     public static boolean optBoolean( @Nonnull Object[] args, int index, boolean def ) throws LuaException
     {
-        Object value = index < args.length ? args[index] : null;
-        if( value == null )
-        {
-            return def;
-        }
-        else if( value instanceof Boolean )
-        {
-            return (Boolean) value;
-        }
-        else
-        {
-            throw badArgument( index, "boolean", value );
-        }
+        return dan200.computercraft.api.lua.ArgumentHelper.optBoolean( args, index, def );
     }
 
     public static String optString( @Nonnull Object[] args, int index, String def ) throws LuaException
     {
-        Object value = index < args.length ? args[index] : null;
-        if( value == null )
-        {
-            return def;
-        }
-        else if( value instanceof String )
-        {
-            return (String) value;
-        }
-        else
-        {
-            throw badArgument( index, "string", value );
-        }
+        return dan200.computercraft.api.lua.ArgumentHelper.optString( args, index, def );
     }
 
     @SuppressWarnings( "unchecked" )
     public static Map<Object, Object> optTable( @Nonnull Object[] args, int index, Map<Object, Object> def ) throws LuaException
     {
-        Object value = index < args.length ? args[index] : null;
-        if( value == null )
-        {
-            return def;
-        }
-        else if( value instanceof Map )
-        {
-            return (Map<Object, Object>) value;
-        }
-        else
-        {
-            throw badArgument( index, "table", value );
-        }
-    }
-
-    private static Number checkReal( int index, Number value ) throws LuaException
-    {
-        checkReal( index, value.doubleValue() );
-        return value;
-    }
-
-    private static double checkReal( int index, double value ) throws LuaException
-    {
-        if( Double.isNaN( value ) )
-        {
-            throw badArgument( index, "number", "nan" );
-        }
-        else if( value == Double.POSITIVE_INFINITY )
-        {
-            throw badArgument( index, "number", "inf" );
-        }
-        else if( value == Double.NEGATIVE_INFINITY )
-        {
-            throw badArgument( index, "number", "-inf" );
-        }
-        else
-        {
-            return value;
-        }
+        return (Map<Object, Object>) dan200.computercraft.api.lua.ArgumentHelper.optTable( args, index, def );
     }
 }

src/main/java/dan200/computercraft/core/apis/ComputerAccess.java

@@ -6,7 +6,6 @@
 
 package dan200.computercraft.core.apis;
 
-import com.google.common.base.Preconditions;
 import dan200.computercraft.api.filesystem.IMount;
 import dan200.computercraft.api.filesystem.IWritableMount;
 import dan200.computercraft.api.peripheral.IComputerAccess;
@@ -121,7 +120,7 @@ public abstract class ComputerAccess implements IComputerAccess
     @Override
     public void queueEvent( @Nonnull final String event, final Object[] arguments )
     {
-        Preconditions.checkNotNull( event, "event cannot be null" );
+        Objects.requireNonNull( event, "event cannot be null" );
         m_environment.queueEvent( event, arguments );
     }
 

src/main/java/dan200/computercraft/core/apis/FSAPI.java

@@ -27,7 +27,7 @@ import java.util.HashMap;
 import java.util.Map;
 import java.util.function.Function;
 
-import static dan200.computercraft.core.apis.ArgumentHelper.getString;
+import static dan200.computercraft.api.lua.ArgumentHelper.getString;
 
 public class FSAPI implements ILuaAPI
 {
@@ -43,9 +43,7 @@ public class FSAPI implements ILuaAPI
     @Override
     public String[] getNames()
     {
-        return new String[] {
-            "fs"
-        };
+        return new String[] { "fs" };
     }
 
     @Override

src/main/java/dan200/computercraft/core/apis/HTTPAPI.java

@@ -23,7 +23,7 @@ import java.util.Collections;
 import java.util.Locale;
 import java.util.Map;
 
-import static dan200.computercraft.core.apis.ArgumentHelper.*;
+import static dan200.computercraft.api.lua.ArgumentHelper.*;
 import static dan200.computercraft.core.apis.TableHelper.*;
 
 public class HTTPAPI implements ILuaAPI
@@ -42,9 +42,7 @@ public class HTTPAPI implements ILuaAPI
     @Override
     public String[] getNames()
     {
-        return new String[] {
-            "http"
-        };
+        return new String[] { "http" };
     }
 
     @Override
@@ -83,6 +81,7 @@ public class HTTPAPI implements ILuaAPI
     }
 
     @Override
+    @SuppressWarnings( "resource" )
     public Object[] callMethod( @Nonnull ILuaContext context, int method, @Nonnull Object[] args ) throws LuaException
     {
         switch( method )
@@ -90,12 +89,12 @@ public class HTTPAPI implements ILuaAPI
             case 0: // request
             {
                 String address, postString, requestMethod;
-                Map<Object, Object> headerTable;
+                Map<?, ?> headerTable;
                 boolean binary, redirect;
 
                 if( args.length >= 1 && args[0] instanceof Map )
                 {
-                    Map<?, ?> options = (Map) args[0];
+                    Map<?, ?> options = (Map<?, ?>) args[0];
                     address = getStringField( options, "url" );
                     postString = optStringField( options, "body", null );
                     headerTable = optTableField( options, "headers", Collections.emptyMap() );
@@ -135,7 +134,6 @@ public class HTTPAPI implements ILuaAPI
                 try
                 {
                     URI uri = HttpRequest.checkUri( address );
-
                     HttpRequest request = new HttpRequest( requests, m_apiEnvironment, address, postString, headers, binary, redirect );
 
                     long requestBody = request.body().readableBytes() + HttpRequest.getHeaderSize( headers );
@@ -174,7 +172,7 @@ public class HTTPAPI implements ILuaAPI
             case 2: // websocket
             {
                 String address = getString( args, 0 );
-                Map<Object, Object> headerTbl = optTable( args, 1, Collections.emptyMap() );
+                Map<?, ?> headerTbl = optTable( args, 1, Collections.emptyMap() );
 
                 if( !ComputerCraft.http_websocket_enable )
                 {

src/main/java/dan200/computercraft/core/apis/IAPIEnvironment.java

@@ -8,6 +8,7 @@ package dan200.computercraft.core.apis;
 
 import dan200.computercraft.api.peripheral.IPeripheral;
 import dan200.computercraft.api.peripheral.IWorkMonitor;
+import dan200.computercraft.core.computer.ComputerSide;
 import dan200.computercraft.core.computer.IComputerEnvironment;
 import dan200.computercraft.core.filesystem.FileSystem;
 import dan200.computercraft.core.terminal.Terminal;
@@ -18,16 +19,10 @@ import javax.annotation.Nullable;
 
 public interface IAPIEnvironment
 {
-    String[] SIDE_NAMES = new String[] {
-        "bottom", "top", "back", "front", "right", "left",
-    };
-
-    int SIDE_COUNT = 6;
-
     @FunctionalInterface
     interface IPeripheralChangeListener
     {
-        void onPeripheralChanged( int side, @Nullable IPeripheral newPeripheral );
+        void onPeripheralChanged( ComputerSide side, @Nullable IPeripheral newPeripheral );
     }
 
     int getComputerID();
@@ -49,22 +44,22 @@ public interface IAPIEnvironment
 
     void queueEvent( String event, Object[] args );
 
-    void setOutput( int side, int output );
+    void setOutput( ComputerSide side, int output );
 
-    int getOutput( int side );
+    int getOutput( ComputerSide side );
 
-    int getInput( int side );
+    int getInput( ComputerSide side );
 
-    void setBundledOutput( int side, int output );
+    void setBundledOutput( ComputerSide side, int output );
 
-    int getBundledOutput( int side );
+    int getBundledOutput( ComputerSide side );
 
-    int getBundledInput( int side );
+    int getBundledInput( ComputerSide side );
 
     void setPeripheralChangeListener( @Nullable IPeripheralChangeListener listener );
 
     @Nullable
-    IPeripheral getPeripheral( int side );
+    IPeripheral getPeripheral( ComputerSide side );
 
     String getLabel();
 

src/main/java/dan200/computercraft/core/apis/ILuaAPI.java

@@ -10,6 +10,7 @@ package dan200.computercraft.core.apis;
  * This exists purely to ensure binary compatibility.
  *
  * @see dan200.computercraft.api.lua.ILuaAPI
+ * @deprecated Use the version in the public API. Only exists for compatibility with CCEmuX.
  */
 @Deprecated
 public interface ILuaAPI extends dan200.computercraft.api.lua.ILuaAPI

src/main/java/dan200/computercraft/core/apis/LuaDateTime.java

@@ -0,0 +1,281 @@
+/*
+ * This file is part of ComputerCraft - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2019. Do not distribute without permission.
+ * Send enquiries to dratcliffe@gmail.com
+ */
+
+package dan200.computercraft.core.apis;
+
+import dan200.computercraft.api.lua.LuaException;
+
+import java.time.Instant;
+import java.time.LocalDateTime;
+import java.time.ZoneId;
+import java.time.ZoneOffset;
+import java.time.format.DateTimeFormatterBuilder;
+import java.time.format.TextStyle;
+import java.time.temporal.*;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.function.LongUnaryOperator;
+
+final class LuaDateTime
+{
+    private LuaDateTime()
+    {
+    }
+
+    static void format( DateTimeFormatterBuilder formatter, String format, ZoneOffset offset ) throws LuaException
+    {
+        for( int i = 0; i < format.length(); )
+        {
+            char c;
+            switch( c = format.charAt( i++ ) )
+            {
+                case '\n':
+                    formatter.appendLiteral( '\n' );
+                    break;
+                default:
+                    formatter.appendLiteral( c );
+                    break;
+                case '%':
+                    if( i >= format.length() ) break;
+                    switch( c = format.charAt( i++ ) )
+                    {
+                        default:
+                            throw new LuaException( "bad argument #1: invalid conversion specifier '%" + c + "'" );
+
+                        case '%':
+                            formatter.appendLiteral( '%' );
+                            break;
+                        case 'a':
+                            formatter.appendText( ChronoField.DAY_OF_WEEK, TextStyle.SHORT );
+                            break;
+                        case 'A':
+                            formatter.appendText( ChronoField.DAY_OF_WEEK, TextStyle.FULL );
+                            break;
+                        case 'b':
+                        case 'h':
+                            formatter.appendText( ChronoField.MONTH_OF_YEAR, TextStyle.SHORT );
+                            break;
+                        case 'B':
+                            formatter.appendText( ChronoField.MONTH_OF_YEAR, TextStyle.FULL );
+                            break;
+                        case 'c':
+                            format( formatter, "%a %b %e %H:%M:%S %Y", offset );
+                            break;
+                        case 'C':
+                            formatter.appendValueReduced( CENTURY, 2, 2, 0 );
+                            break;
+                        case 'd':
+                            formatter.appendValue( ChronoField.DAY_OF_MONTH, 2 );
+                            break;
+                        case 'D':
+                        case 'x':
+                            format( formatter, "%m/%d/%y", offset );
+                            break;
+                        case 'e':
+                            formatter.padNext( 2 ).appendValue( ChronoField.DAY_OF_MONTH );
+                            break;
+                        case 'F':
+                            format( formatter, "%Y-%m-%d", offset );
+                            break;
+                        case 'g':
+                            formatter.appendValueReduced( IsoFields.WEEK_BASED_YEAR, 2, 2, 0 );
+                            break;
+                        case 'G':
+                            formatter.appendValue( IsoFields.WEEK_BASED_YEAR );
+                            break;
+                        case 'H':
+                            formatter.appendValue( ChronoField.HOUR_OF_DAY, 2 );
+                            break;
+                        case 'I':
+                            formatter.appendValue( ChronoField.HOUR_OF_AMPM );
+                            break;
+                        case 'j':
+                            formatter.appendValue( ChronoField.DAY_OF_YEAR, 3 );
+                            break;
+                        case 'm':
+                            formatter.appendValue( ChronoField.MONTH_OF_YEAR, 2 );
+                            break;
+                        case 'M':
+                            formatter.appendValue( ChronoField.MINUTE_OF_HOUR, 2 );
+                            break;
+                        case 'n':
+                            formatter.appendLiteral( '\n' );
+                            break;
+                        case 'p':
+                            formatter.appendText( ChronoField.AMPM_OF_DAY );
+                            break;
+                        case 'r':
+                            format( formatter, "%I:%M:%S %p", offset );
+                            break;
+                        case 'R':
+                            format( formatter, "%H:%M", offset );
+                            break;
+                        case 'S':
+                            formatter.appendValue( ChronoField.SECOND_OF_MINUTE, 2 );
+                            break;
+                        case 't':
+                            formatter.appendLiteral( '\t' );
+                            break;
+                        case 'T':
+                        case 'X':
+                            format( formatter, "%H:%M:%S", offset );
+                            break;
+                        case 'u':
+                            formatter.appendValue( ChronoField.DAY_OF_WEEK );
+                            break;
+                        case 'U':
+                            formatter.appendValue( ChronoField.ALIGNED_WEEK_OF_YEAR, 2 );
+                            break;
+                        case 'V':
+                            formatter.appendValue( IsoFields.WEEK_OF_WEEK_BASED_YEAR, 2 );
+                            break;
+                        case 'w':
+                            formatter.appendValue( ZERO_WEEK );
+                            break;
+                        case 'W':
+                            formatter.appendValue( WeekFields.ISO.weekOfYear(), 2 );
+                            break;
+                        case 'y':
+                            formatter.appendValueReduced( ChronoField.YEAR, 2, 2, 0 );
+                            break;
+                        case 'Y':
+                            formatter.appendValue( ChronoField.YEAR );
+                            break;
+                        case 'z':
+                            formatter.appendOffset( "+HHMM", "+0000" );
+                            break;
+                        case 'Z':
+                            formatter.appendChronologyId();
+                            break;
+                    }
+            }
+        }
+    }
+
+    static long fromTable( Map<?, ?> table ) throws LuaException
+    {
+        int year = getField( table, "year", -1 );
+        int month = getField( table, "month", -1 );
+        int day = getField( table, "day", -1 );
+        int hour = getField( table, "hour", 12 );
+        int minute = getField( table, "min", 12 );
+        int second = getField( table, "sec", 12 );
+        LocalDateTime time = LocalDateTime.of( year, month, day, hour, minute, second );
+
+        Boolean isDst = getBoolField( table, "isdst" );
+        if( isDst != null )
+        {
+            boolean requireDst = isDst;
+            for( ZoneOffset possibleOffset : ZoneOffset.systemDefault().getRules().getValidOffsets( time ) )
+            {
+                Instant instant = time.toInstant( possibleOffset );
+                if( possibleOffset.getRules().getDaylightSavings( instant ).isZero() == requireDst )
+                {
+                    return instant.getEpochSecond();
+                }
+            }
+        }
+
+        ZoneOffset offset = ZoneOffset.systemDefault().getRules().getOffset( time );
+        return time.toInstant( offset ).getEpochSecond();
+    }
+
+    static Map<String, ?> toTable( TemporalAccessor date, ZoneId offset, Instant instant )
+    {
+        HashMap<String, Object> table = new HashMap<>( 9 );
+        table.put( "year", date.getLong( ChronoField.YEAR ) );
+        table.put( "month", date.getLong( ChronoField.MONTH_OF_YEAR ) );
+        table.put( "day", date.getLong( ChronoField.DAY_OF_MONTH ) );
+        table.put( "hour", date.getLong( ChronoField.HOUR_OF_DAY ) );
+        table.put( "min", date.getLong( ChronoField.MINUTE_OF_HOUR ) );
+        table.put( "sec", date.getLong( ChronoField.SECOND_OF_MINUTE ) );
+        table.put( "wday", date.getLong( WeekFields.SUNDAY_START.dayOfWeek() ) );
+        table.put( "yday", date.getLong( ChronoField.DAY_OF_YEAR ) );
+        table.put( "isdst", offset.getRules().isDaylightSavings( instant ) );
+        return table;
+    }
+
+    private static int getField( Map<?, ?> table, String field, int def ) throws LuaException
+    {
+        Object value = table.get( field );
+        if( value instanceof Number ) return ((Number) value).intValue();
+        if( def < 0 ) throw new LuaException( "field \"" + field + "\" missing in date table" );
+        return def;
+    }
+
+    private static Boolean getBoolField( Map<?, ?> table, String field ) throws LuaException
+    {
+        Object value = table.get( field );
+        if( value instanceof Boolean || value == null ) return (Boolean) value;
+        throw new LuaException( "field \"" + field + "\" missing in date table" );
+    }
+
+    private static final TemporalField CENTURY = map( ChronoField.YEAR, ValueRange.of( 0, 6 ), x -> (x / 100) % 100 );
+    private static final TemporalField ZERO_WEEK = map( WeekFields.SUNDAY_START.dayOfWeek(), ValueRange.of( 0, 6 ), x -> x - 1 );
+
+    private static TemporalField map( TemporalField field, ValueRange range, LongUnaryOperator convert )
+    {
+        return new TemporalField()
+        {
+            private final ValueRange range = ValueRange.of( 0, 99 );
+
+            @Override
+            public TemporalUnit getBaseUnit()
+            {
+                return field.getBaseUnit();
+            }
+
+            @Override
+            public TemporalUnit getRangeUnit()
+            {
+                return field.getRangeUnit();
+            }
+
+            @Override
+            public ValueRange range()
+            {
+                return range;
+            }
+
+            @Override
+            public boolean isDateBased()
+            {
+                return field.isDateBased();
+            }
+
+            @Override
+            public boolean isTimeBased()
+            {
+                return field.isTimeBased();
+            }
+
+            @Override
+            public boolean isSupportedBy( TemporalAccessor temporal )
+            {
+                return field.isSupportedBy( temporal );
+            }
+
+            @Override
+            public ValueRange rangeRefinedBy( TemporalAccessor temporal )
+            {
+                return range;
+            }
+
+            @Override
+            public long getFrom( TemporalAccessor temporal )
+            {
+                return convert.applyAsLong( temporal.getLong( field ) );
+            }
+
+            @Override
+            @SuppressWarnings( "unchecked" )
+            public <R extends Temporal> R adjustInto( R temporal, long newValue )
+            {
+                return (R) temporal.with( field, newValue );
+            }
+        };
+    }
+}

src/main/java/dan200/computercraft/core/apis/OSAPI.java

@@ -12,9 +12,14 @@ import dan200.computercraft.api.lua.LuaException;
 import dan200.computercraft.shared.util.StringUtil;
 
 import javax.annotation.Nonnull;
+import java.time.Instant;
+import java.time.ZoneId;
+import java.time.ZoneOffset;
+import java.time.ZonedDateTime;
+import java.time.format.DateTimeFormatterBuilder;
 import java.util.*;
 
-import static dan200.computercraft.core.apis.ArgumentHelper.*;
+import static dan200.computercraft.api.lua.ArgumentHelper.*;
 
 public class OSAPI implements ILuaAPI
 {
@@ -31,9 +36,9 @@ public class OSAPI implements ILuaAPI
 
     private static class Timer
     {
-        public int m_ticksLeft;
+        int m_ticksLeft;
 
-        public Timer( int ticksLeft )
+        Timer( int ticksLeft )
         {
             m_ticksLeft = ticksLeft;
         }
@@ -41,10 +46,10 @@ public class OSAPI implements ILuaAPI
 
     private static class Alarm implements Comparable<Alarm>
     {
-        public final double m_time;
-        public final int m_day;
+        final double m_time;
+        final int m_day;
 
-        public Alarm( double time, int day )
+        Alarm( double time, int day )
         {
             m_time = time;
             m_day = day;
@@ -73,9 +78,7 @@ public class OSAPI implements ILuaAPI
     @Override
     public String[] getNames()
     {
-        return new String[] {
-            "os"
-        };
+        return new String[] { "os" };
     }
 
     @Override
@@ -184,11 +187,12 @@ public class OSAPI implements ILuaAPI
             "day",
             "cancelTimer",
             "cancelAlarm",
-            "epoch"
+            "epoch",
+            "date",
         };
     }
 
-    private float getTimeForCalendar( Calendar c )
+    private static float getTimeForCalendar( Calendar c )
     {
         float time = c.get( Calendar.HOUR_OF_DAY );
         time += c.get( Calendar.MINUTE ) / 60.0f;
@@ -196,7 +200,7 @@ public class OSAPI implements ILuaAPI
         return time;
     }
 
-    private int getDayForCalendar( Calendar c )
+    private static int getDayForCalendar( Calendar c )
     {
         GregorianCalendar g = c instanceof GregorianCalendar ? (GregorianCalendar) c : new GregorianCalendar();
         int year = c.get( Calendar.YEAR );
@@ -209,7 +213,7 @@ public class OSAPI implements ILuaAPI
         return day;
     }
 
-    private long getEpochForCalendar( Calendar c )
+    private static long getEpochForCalendar( Calendar c )
     {
         return c.getTime().getTime();
     }
@@ -225,7 +229,7 @@ public class OSAPI implements ILuaAPI
             case 1:
             {
                 // startTimer
-                double timer = getReal( args, 0 );
+                double timer = getFiniteDouble( args, 0 );
                 synchronized( m_timers )
                 {
                     m_timers.put( m_nextTimerToken, new Timer( (int) Math.round( timer / 0.05 ) ) );
@@ -235,7 +239,7 @@ public class OSAPI implements ILuaAPI
             case 2:
             {
                 // setAlarm
-                double time = getReal( args, 0 );
+                double time = getFiniteDouble( args, 0 );
                 if( time < 0.0 || time >= 24.0 )
                 {
                     throw new LuaException( "Number out of range" );
@@ -282,6 +286,9 @@ public class OSAPI implements ILuaAPI
             case 11:
             {
                 // time
+                Object value = args.length > 0 ? args[0] : null;
+                if( value instanceof Map ) return new Object[] { LuaDateTime.fromTable( (Map<?, ?>) value ) };
+
                 String param = optString( args, 0, "ingame" );
                 switch( param.toLowerCase( Locale.ROOT ) )
                 {
@@ -355,9 +362,8 @@ public class OSAPI implements ILuaAPI
                 }
                 return null;
             }
-            case 15:
+            case 15: // epoch
             {
-                // epoch
                 String param = optString( args, 0, "ingame" );
                 switch( param.toLowerCase( Locale.ROOT ) )
                 {
@@ -377,14 +383,39 @@ public class OSAPI implements ILuaAPI
                         // Get in-game epoch
                         synchronized( m_alarms )
                         {
-                            return new Object[] {
-                                m_day * 86400000 + (int) (m_time * 3600000.0f)
-                            };
+                            return new Object[] { m_day * 86400000 + (int) (m_time * 3600000.0f) };
                         }
                     default:
                         throw new LuaException( "Unsupported operation" );
                 }
             }
+            case 16: // date
+            {
+                String format = optString( args, 0, "%c" );
+                long time = optLong( args, 1, Instant.now().getEpochSecond() );
+
+                Instant instant = Instant.ofEpochSecond( time );
+                ZonedDateTime date;
+                ZoneOffset offset;
+                if( format.startsWith( "!" ) )
+                {
+                    offset = ZoneOffset.UTC;
+                    date = ZonedDateTime.ofInstant( instant, offset );
+                    format = format.substring( 1 );
+                }
+                else
+                {
+                    ZoneId id = ZoneId.systemDefault();
+                    offset = id.getRules().getOffset( instant );
+                    date = ZonedDateTime.ofInstant( instant, id );
+                }
+
+                if( format.equals( "*t" ) ) return new Object[] { LuaDateTime.toTable( date, offset, instant ) };
+
+                DateTimeFormatterBuilder formatter = new DateTimeFormatterBuilder();
+                LuaDateTime.format( formatter, format, offset );
+                return new Object[] { formatter.toFormatter( Locale.ROOT ).format( date ) };
+            }
             default:
                 return null;
         }

src/main/java/dan200/computercraft/core/apis/PeripheralAPI.java

@@ -12,6 +12,7 @@ import dan200.computercraft.api.lua.ILuaAPI;
 import dan200.computercraft.api.lua.ILuaContext;
 import dan200.computercraft.api.lua.LuaException;
 import dan200.computercraft.api.peripheral.IPeripheral;
+import dan200.computercraft.core.computer.ComputerSide;
 import dan200.computercraft.core.tracking.TrackingField;
 
 import javax.annotation.Nonnull;
@@ -21,7 +22,7 @@ import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
 
-import static dan200.computercraft.core.apis.ArgumentHelper.getString;
+import static dan200.computercraft.api.lua.ArgumentHelper.getString;
 
 public class PeripheralAPI implements ILuaAPI, IAPIEnvironment.IPeripheralChangeListener
 {
@@ -35,7 +36,7 @@ public class PeripheralAPI implements ILuaAPI, IAPIEnvironment.IPeripheralChange
         private Map<String, Integer> m_methodMap;
         private boolean m_attached;
 
-        public PeripheralWrapper( IPeripheral peripheral, String side )
+        PeripheralWrapper( IPeripheral peripheral, String side )
         {
             super( m_environment );
             m_side = side;
@@ -245,32 +246,33 @@ public class PeripheralAPI implements ILuaAPI, IAPIEnvironment.IPeripheralChange
     // IPeripheralChangeListener
 
     @Override
-    public void onPeripheralChanged( int side, IPeripheral newPeripheral )
+    public void onPeripheralChanged( ComputerSide side, IPeripheral newPeripheral )
     {
         synchronized( m_peripherals )
         {
-            if( m_peripherals[side] != null )
+            int index = side.ordinal();
+            if( m_peripherals[index] != null )
             {
                 // Queue a detachment
-                final PeripheralWrapper wrapper = m_peripherals[side];
+                final PeripheralWrapper wrapper = m_peripherals[index];
                 if( wrapper.isAttached() ) wrapper.detach();
 
                 // Queue a detachment event
-                m_environment.queueEvent( "peripheral_detach", new Object[] { IAPIEnvironment.SIDE_NAMES[side] } );
+                m_environment.queueEvent( "peripheral_detach", new Object[] { side.getName() } );
             }
 
             // Assign the new peripheral
-            m_peripherals[side] = newPeripheral == null ? null
-                : new PeripheralWrapper( newPeripheral, IAPIEnvironment.SIDE_NAMES[side] );
+            m_peripherals[index] = newPeripheral == null ? null
+                : new PeripheralWrapper( newPeripheral, side.getName() );
 
-            if( m_peripherals[side] != null )
+            if( m_peripherals[index] != null )
             {
                 // Queue an attachment
-                final PeripheralWrapper wrapper = m_peripherals[side];
+                final PeripheralWrapper wrapper = m_peripherals[index];
                 if( m_running && !wrapper.isAttached() ) wrapper.attach();
 
                 // Queue an attachment event
-                m_environment.queueEvent( "peripheral", new Object[] { IAPIEnvironment.SIDE_NAMES[side] } );
+                m_environment.queueEvent( "peripheral", new Object[] { side.getName() } );
             }
         }
     }
@@ -280,9 +282,7 @@ public class PeripheralAPI implements ILuaAPI, IAPIEnvironment.IPeripheralChange
     @Override
     public String[] getNames()
     {
-        return new String[] {
-            "peripheral"
-        };
+        return new String[] { "peripheral" };
     }
 
     @Override
@@ -324,7 +324,7 @@ public class PeripheralAPI implements ILuaAPI, IAPIEnvironment.IPeripheralChange
             "isPresent",
             "getType",
             "getMethods",
-            "call"
+            "call",
         };
     }
 
@@ -337,16 +337,13 @@ public class PeripheralAPI implements ILuaAPI, IAPIEnvironment.IPeripheralChange
             {
                 // isPresent
                 boolean present = false;
-                int side = parseSide( args );
-                if( side >= 0 )
+                ComputerSide side = ComputerSide.valueOfInsensitive( getString( args, 0 ) );
+                if( side != null )
                 {
                     synchronized( m_peripherals )
                     {
-                        PeripheralWrapper p = m_peripherals[side];
-                        if( p != null )
-                        {
-                            present = true;
-                        }
+                        PeripheralWrapper p = m_peripherals[side.ordinal()];
+                        if( p != null ) present = true;
                     }
                 }
                 return new Object[] { present };
@@ -354,21 +351,13 @@ public class PeripheralAPI implements ILuaAPI, IAPIEnvironment.IPeripheralChange
             case 1:
             {
                 // getType
-                String type = null;
-                int side = parseSide( args );
-                if( side >= 0 )
+                ComputerSide side = ComputerSide.valueOfInsensitive( getString( args, 0 ) );
+                if( side != null )
                 {
                     synchronized( m_peripherals )
                     {
-                        PeripheralWrapper p = m_peripherals[side];
-                        if( p != null )
-                        {
-                            type = p.getType();
-                        }
-                    }
-                    if( type != null )
-                    {
-                        return new Object[] { type };
+                        PeripheralWrapper p = m_peripherals[side.ordinal()];
+                        if( p != null ) return new Object[] { p.getType() };
                     }
                 }
                 return null;
@@ -377,12 +366,12 @@ public class PeripheralAPI implements ILuaAPI, IAPIEnvironment.IPeripheralChange
             {
                 // getMethods
                 String[] methods = null;
-                int side = parseSide( args );
-                if( side >= 0 )
+                ComputerSide side = ComputerSide.valueOfInsensitive( getString( args, 0 ) );
+                if( side != null )
                 {
                     synchronized( m_peripherals )
                     {
-                        PeripheralWrapper p = m_peripherals[side];
+                        PeripheralWrapper p = m_peripherals[side.ordinal()];
                         if( p != null )
                         {
                             methods = p.getMethods();
@@ -403,16 +392,16 @@ public class PeripheralAPI implements ILuaAPI, IAPIEnvironment.IPeripheralChange
             case 3:
             {
                 // call
-                int side = parseSide( args );
+                ComputerSide side = ComputerSide.valueOfInsensitive( getString( args, 0 ) );
                 String methodName = getString( args, 1 );
                 Object[] methodArgs = Arrays.copyOfRange( args, 2, args.length );
 
-                if( side >= 0 )
+                if( side != null )
                 {
                     PeripheralWrapper p;
                     synchronized( m_peripherals )
                     {
-                        p = m_peripherals[side];
+                        p = m_peripherals[side.ordinal()];
                     }
                     if( p != null )
                     {
@@ -425,19 +414,4 @@ public class PeripheralAPI implements ILuaAPI, IAPIEnvironment.IPeripheralChange
                 return null;
         }
     }
-
-    // Privates
-
-    private int parseSide( Object[] args ) throws LuaException
-    {
-        String side = getString( args, 0 );
-        for( int n = 0; n < IAPIEnvironment.SIDE_NAMES.length; n++ )
-        {
-            if( side.equals( IAPIEnvironment.SIDE_NAMES[n] ) )
-            {
-                return n;
-            }
-        }
-        return -1;
-    }
 }

src/main/java/dan200/computercraft/core/apis/RedstoneAPI.java

@@ -9,12 +9,13 @@ package dan200.computercraft.core.apis;
 import dan200.computercraft.api.lua.ILuaAPI;
 import dan200.computercraft.api.lua.ILuaContext;
 import dan200.computercraft.api.lua.LuaException;
+import dan200.computercraft.core.computer.ComputerSide;
 
 import javax.annotation.Nonnull;
 import java.util.HashMap;
 import java.util.Map;
 
-import static dan200.computercraft.core.apis.ArgumentHelper.*;
+import static dan200.computercraft.api.lua.ArgumentHelper.*;
 
 public class RedstoneAPI implements ILuaAPI
 {
@@ -28,9 +29,7 @@ public class RedstoneAPI implements ILuaAPI
     @Override
     public String[] getNames()
     {
-        return new String[] {
-            "rs", "redstone"
-        };
+        return new String[] { "rs", "redstone" };
     }
 
     @Nonnull
@@ -64,56 +63,40 @@ public class RedstoneAPI implements ILuaAPI
             {
                 // getSides
                 Map<Object, Object> table = new HashMap<>();
-                for( int i = 0; i < IAPIEnvironment.SIDE_NAMES.length; i++ )
+                for( int i = 0; i < ComputerSide.NAMES.length; i++ )
                 {
-                    table.put( i + 1, IAPIEnvironment.SIDE_NAMES[i] );
+                    table.put( i + 1, ComputerSide.NAMES[i] );
                 }
                 return new Object[] { table };
             }
             case 1:
             {
                 // setOutput
-                int side = parseSide( args );
+                ComputerSide side = parseSide( args );
                 boolean output = getBoolean( args, 1 );
                 m_environment.setOutput( side, output ? 15 : 0 );
                 return null;
             }
-            case 2:
-            {
-                // getOutput
-                int side = parseSide( args );
-                return new Object[] { m_environment.getOutput( side ) > 0 };
-            }
-            case 3:
-            {
-                // getInput
-                int side = parseSide( args );
-                return new Object[] { m_environment.getInput( side ) > 0 };
-            }
+            case 2: // getOutput
+                return new Object[] { m_environment.getOutput( parseSide( args ) ) > 0 };
+            case 3: // getInput
+                return new Object[] { m_environment.getInput( parseSide( args ) ) > 0 };
             case 4:
             {
                 // setBundledOutput
-                int side = parseSide( args );
+                ComputerSide side = parseSide( args );
                 int output = getInt( args, 1 );
                 m_environment.setBundledOutput( side, output );
                 return null;
             }
-            case 5:
-            {
-                // getBundledOutput
-                int side = parseSide( args );
-                return new Object[] { m_environment.getBundledOutput( side ) };
-            }
-            case 6:
-            {
-                // getBundledInput
-                int side = parseSide( args );
-                return new Object[] { m_environment.getBundledInput( side ) };
-            }
+            case 5: // getBundledOutput
+                return new Object[] { m_environment.getBundledOutput( parseSide( args ) ) };
+            case 6: // getBundledInput
+                return new Object[] { m_environment.getBundledInput( parseSide( args ) ) };
             case 7:
             {
                 // testBundledInput
-                int side = parseSide( args );
+                ComputerSide side = parseSide( args );
                 int mask = getInt( args, 1 );
                 int input = m_environment.getBundledInput( side );
                 return new Object[] { (input & mask) == mask };
@@ -122,7 +105,7 @@ public class RedstoneAPI implements ILuaAPI
             case 9:
             {
                 // setAnalogOutput/setAnalogueOutput
-                int side = parseSide( args );
+                ComputerSide side = parseSide( args );
                 int output = getInt( args, 1 );
                 if( output < 0 || output > 15 )
                 {
@@ -132,34 +115,20 @@ public class RedstoneAPI implements ILuaAPI
                 return null;
             }
             case 10:
-            case 11:
-            {
-                // getAnalogOutput/getAnalogueOutput
-                int side = parseSide( args );
-                return new Object[] { m_environment.getOutput( side ) };
-            }
+            case 11: // getAnalogOutput/getAnalogueOutput
+                return new Object[] { m_environment.getOutput( parseSide( args ) ) };
             case 12:
-            case 13:
-            {
-                // getAnalogInput/getAnalogueInput
-                int side = parseSide( args );
-                return new Object[] { m_environment.getInput( side ) };
-            }
+            case 13: // getAnalogInput/getAnalogueInput
+                return new Object[] { m_environment.getInput( parseSide( args ) ) };
             default:
                 return null;
         }
     }
 
-    private static int parseSide( Object[] args ) throws LuaException
+    private static ComputerSide parseSide( Object[] args ) throws LuaException
     {
-        String side = getString( args, 0 );
-        for( int n = 0; n < IAPIEnvironment.SIDE_NAMES.length; n++ )
-        {
-            if( side.equals( IAPIEnvironment.SIDE_NAMES[n] ) )
-            {
-                return n;
-            }
-        }
-        throw new LuaException( "Invalid side." );
+        ComputerSide side = ComputerSide.valueOfInsensitive( getString( args, 0 ) );
+        if( side == null ) throw new LuaException( "Invalid side." );
+        return side;
     }
 }

src/main/java/dan200/computercraft/core/apis/TableHelper.java

@@ -6,14 +6,17 @@
 
 package dan200.computercraft.core.apis;
 
+import dan200.computercraft.api.lua.ArgumentHelper;
 import dan200.computercraft.api.lua.LuaException;
 
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 import java.util.Map;
 
+import static dan200.computercraft.api.lua.ArgumentHelper.getNumericType;
+
 /**
- * Various helpers for tables
+ * Various helpers for tables.
  */
 public final class TableHelper
 {
@@ -200,21 +203,7 @@ public final class TableHelper
 
     private static double checkReal( @Nonnull String key, double value ) throws LuaException
     {
-        if( Double.isNaN( value ) )
-        {
-            throw badKey( key, "number", "nan" );
-        }
-        else if( value == Double.POSITIVE_INFINITY )
-        {
-            throw badKey( key, "number", "inf" );
-        }
-        else if( value == Double.NEGATIVE_INFINITY )
-        {
-            throw badKey( key, "number", "-inf" );
-        }
-        else
-        {
-            return value;
-        }
+        if( !Double.isFinite( value ) ) throw badKey( key, "number", getNumericType( value ) );
+        return value;
     }
 }

src/main/java/dan200/computercraft/core/apis/TermAPI.java

@@ -17,7 +17,7 @@ import org.apache.commons.lang3.ArrayUtils;
 
 import javax.annotation.Nonnull;
 
-import static dan200.computercraft.core.apis.ArgumentHelper.*;
+import static dan200.computercraft.api.lua.ArgumentHelper.*;
 
 public class TermAPI implements ILuaAPI
 {
@@ -33,9 +33,7 @@ public class TermAPI implements ILuaAPI
     @Override
     public String[] getNames()
     {
-        return new String[] {
-            "term"
-        };
+        return new String[] { "term" };
     }
 
     @Nonnull
@@ -89,9 +87,7 @@ public class TermAPI implements ILuaAPI
 
     public static Object[] encodeColour( int colour ) throws LuaException
     {
-        return new Object[] {
-            1 << colour
-        };
+        return new Object[] { 1 << colour };
     }
 
     public static void setColour( Terminal terminal, int colour, double r, double g, double b )
@@ -246,9 +242,9 @@ public class TermAPI implements ILuaAPI
                 }
                 else
                 {
-                    double r = getReal( args, 1 );
-                    double g = getReal( args, 2 );
-                    double b = getReal( args, 3 );
+                    double r = getFiniteDouble( args, 1 );
+                    double g = getFiniteDouble( args, 2 );
+                    double b = getFiniteDouble( args, 3 );
                     setColour( m_terminal, colour, r, g, b );
                 }
                 return null;

src/main/java/dan200/computercraft/core/apis/handles/BinaryReadableHandle.java

@@ -21,8 +21,8 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 
-import static dan200.computercraft.core.apis.ArgumentHelper.getInt;
-import static dan200.computercraft.core.apis.ArgumentHelper.optBoolean;
+import static dan200.computercraft.api.lua.ArgumentHelper.getInt;
+import static dan200.computercraft.api.lua.ArgumentHelper.optBoolean;
 
 public class BinaryReadableHandle extends HandleGeneric
 {
@@ -212,6 +212,7 @@ public class BinaryReadableHandle extends HandleGeneric
                 }
             }
             case 3: // close
+                checkOpen();
                 close();
                 return null;
             case 4: // seek

src/main/java/dan200/computercraft/core/apis/handles/BinaryWritableHandle.java

@@ -7,9 +7,9 @@
 package dan200.computercraft.core.apis.handles;
 
 import com.google.common.collect.ObjectArrays;
+import dan200.computercraft.api.lua.ArgumentHelper;
 import dan200.computercraft.api.lua.ILuaContext;
 import dan200.computercraft.api.lua.LuaException;
-import dan200.computercraft.core.apis.ArgumentHelper;
 import dan200.computercraft.shared.util.StringUtil;
 
 import javax.annotation.Nonnull;
@@ -73,7 +73,7 @@ public class BinaryWritableHandle extends HandleGeneric
                     }
                     else
                     {
-                        throw ArgumentHelper.badArgument( 0, "string or number", args.length > 0 ? args[0] : null );
+                        throw ArgumentHelper.badArgumentOf( 0, "string or number", args.length > 0 ? args[0] : null );
                     }
                     return null;
                 }
@@ -95,6 +95,7 @@ public class BinaryWritableHandle extends HandleGeneric
                     return null;
                 }
             case 2: // close
+                checkOpen();
                 close();
                 return null;
             case 3: // seek

src/main/java/dan200/computercraft/core/apis/handles/EncodedReadableHandle.java

@@ -20,8 +20,8 @@ import java.nio.charset.CharsetDecoder;
 import java.nio.charset.CodingErrorAction;
 import java.nio.charset.StandardCharsets;
 
-import static dan200.computercraft.core.apis.ArgumentHelper.optBoolean;
-import static dan200.computercraft.core.apis.ArgumentHelper.optInt;
+import static dan200.computercraft.api.lua.ArgumentHelper.optBoolean;
+import static dan200.computercraft.api.lua.ArgumentHelper.optInt;
 
 public class EncodedReadableHandle extends HandleGeneric
 {
@@ -152,6 +152,7 @@ public class EncodedReadableHandle extends HandleGeneric
                     return null;
                 }
             case 3: // close
+                checkOpen();
                 close();
                 return null;
             default:

src/main/java/dan200/computercraft/core/apis/handles/EncodedWritableHandle.java

@@ -93,6 +93,7 @@ public class EncodedWritableHandle extends HandleGeneric
                     return null;
                 }
             case 3: // close
+                checkOpen();
                 close();
                 return null;
             default:

src/main/java/dan200/computercraft/core/apis/handles/HandleGeneric.java

@@ -16,8 +16,8 @@ import java.io.IOException;
 import java.nio.channels.Channel;
 import java.nio.channels.SeekableByteChannel;
 
-import static dan200.computercraft.core.apis.ArgumentHelper.optLong;
-import static dan200.computercraft.core.apis.ArgumentHelper.optString;
+import static dan200.computercraft.api.lua.ArgumentHelper.optLong;
+import static dan200.computercraft.api.lua.ArgumentHelper.optString;
 
 public abstract class HandleGeneric implements ILuaObject
 {
@@ -37,12 +37,17 @@ public abstract class HandleGeneric implements ILuaObject
     protected final void close()
     {
         m_open = false;
-        IoUtil.closeQuietly( m_closable );
-        m_closable = null;
+
+        Closeable closeable = m_closable;
+        if( closeable != null )
+        {
+            IoUtil.closeQuietly( closeable );
+            m_closable = null;
+        }
     }
 
     /**
-     * Shared implementation for various file handle types
+     * Shared implementation for various file handle types.
      *
      * @param channel The channel to seek in
      * @param args    The Lua arguments to process, like Lua's {@code file:seek}.

src/main/java/dan200/computercraft/core/apis/http/NetworkUtils.java

@@ -99,7 +99,7 @@ public final class NetworkUtils
     }
 
     /**
-     * Checks a host is allowed
+     * Checks a host is allowed.
      *
      * @param host The domain to check against
      * @throws HTTPRequestException If the host is not permitted.

src/main/java/dan200/computercraft/core/apis/http/Resource.java

@@ -20,6 +20,8 @@ import java.util.function.Consumer;
 
 /**
  * A holder for one or more resources, with a lifetime.
+ *
+ * @param <T> The type of this resource. Should be the class extending from {@link Resource}.
  */
 public abstract class Resource<T extends Resource<T>> implements Closeable
 {
@@ -42,8 +44,9 @@ public abstract class Resource<T extends Resource<T>> implements Closeable
     }
 
     /**
-     * Checks if this has been cancelled. If so, it'll clean up any
-     * existing resources and cancel any pending futures.
+     * Checks if this has been cancelled. If so, it'll clean up any existing resources and cancel any pending futures.
+     *
+     * @return Whether this resource has been closed.
      */
     public final boolean checkClosed()
     {
@@ -72,13 +75,15 @@ public abstract class Resource<T extends Resource<T>> implements Closeable
      */
     protected void dispose()
     {
-        @SuppressWarnings( "unchecked" ) T thisT = (T) this;
+        @SuppressWarnings( "unchecked" )
+        T thisT = (T) this;
         limiter.release( thisT );
     }
 
     /**
      * Create a {@link WeakReference} which will close {@code this} when collected.
      *
+     * @param <R>    The object we are wrapping in a reference.
      * @param object The object to reference to
      * @return The weak reference.
      */
@@ -95,7 +100,8 @@ public abstract class Resource<T extends Resource<T>> implements Closeable
 
     public boolean queue( Consumer<T> task )
     {
-        @SuppressWarnings( "unchecked" ) T thisT = (T) this;
+        @SuppressWarnings( "unchecked" )
+        T thisT = (T) this;
         return limiter.queue( thisT, () -> task.accept( thisT ) );
     }
 

src/main/java/dan200/computercraft/core/apis/http/ResourceGroup.java

@@ -14,6 +14,8 @@ import java.util.function.Supplier;
 
 /**
  * A collection of {@link Resource}s, with an upper bound on capacity.
+ *
+ * @param <T> The type of the resource this group manages.
  */
 public class ResourceGroup<T extends Resource<T>>
 {

src/main/java/dan200/computercraft/core/apis/http/ResourceQueue.java

@@ -12,6 +12,8 @@ import java.util.function.Supplier;
 
 /**
  * A {@link ResourceGroup} which will queue items when the group at capacity.
+ *
+ * @param <T> The type of the resource this queue manages.
  */
 public class ResourceQueue<T extends Resource<T>> extends ResourceGroup<T>
 {

src/main/java/dan200/computercraft/core/apis/http/request/HttpRequest.java

@@ -40,7 +40,7 @@ import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicInteger;
 
 /**
- * Represents one or more
+ * Represents an in-progress HTTP request.
  */
 public class HttpRequest extends Resource<HttpRequest>
 {

src/main/java/dan200/computercraft/core/apis/http/request/HttpRequestHandler.java

@@ -226,7 +226,11 @@ public final class HttpRequestHandler extends SimpleChannelInboundHandler<HttpOb
     }
 
     /**
-     * Determine the redirect from this response
+     * Determine the redirect from this response.
+     *
+     * @param status  The status of the HTTP response.
+     * @param headers The headers of the HTTP response.
+     * @return The URI to redirect to, or {@code null} if no redirect should occur.
      */
     private URI getRedirect( HttpResponseStatus status, HttpHeaders headers )
     {

src/main/java/dan200/computercraft/core/apis/http/websocket/WebsocketHandle.java

@@ -23,7 +23,8 @@ import javax.annotation.Nullable;
 import java.io.Closeable;
 import java.util.Arrays;
 
-import static dan200.computercraft.core.apis.ArgumentHelper.optBoolean;
+import static dan200.computercraft.api.lua.ArgumentHelper.optBoolean;
+import static dan200.computercraft.core.apis.http.websocket.Websocket.CLOSE_EVENT;
 import static dan200.computercraft.core.apis.http.websocket.Websocket.MESSAGE_EVENT;
 
 public class WebsocketHandle implements ILuaObject, Closeable
@@ -53,15 +54,18 @@ public class WebsocketHandle implements ILuaObject, Closeable
         switch( method )
         {
             case 0: // receive
+                checkOpen();
                 while( true )
                 {
-                    checkOpen();
-
-                    Object[] event = context.pullEvent( MESSAGE_EVENT );
-                    if( event.length >= 3 && Objects.equal( event[1], websocket.address() ) )
+                    Object[] event = context.pullEvent( null );
+                    if( event.length >= 3 && Objects.equal( event[0], MESSAGE_EVENT ) && Objects.equal( event[1], websocket.address() ) )
                     {
                         return Arrays.copyOfRange( event, 2, event.length );
                     }
+                    else if( event.length >= 2 && Objects.equal( event[0], CLOSE_EVENT ) && Objects.equal( event[1], websocket.address() ) && closed )
+                    {
+                        return null;
+                    }
                 }
 
             case 1: // send

src/main/java/dan200/computercraft/core/computer/Computer.java

@@ -7,6 +7,7 @@
 package dan200.computercraft.core.computer;
 
 import com.google.common.base.Objects;
+import dan200.computercraft.api.filesystem.IWritableMount;
 import dan200.computercraft.api.lua.ILuaAPI;
 import dan200.computercraft.api.peripheral.IPeripheral;
 import dan200.computercraft.api.peripheral.IWorkMonitor;
@@ -222,13 +223,13 @@ public class Computer
     @Deprecated
     public IPeripheral getPeripheral( int side )
     {
-        return internalEnvironment.getPeripheral( side );
+        return internalEnvironment.getPeripheral( ComputerSide.valueOf( side ) );
     }
 
     @Deprecated
     public void setPeripheral( int side, IPeripheral peripheral )
     {
-        internalEnvironment.setPeripheral( side, peripheral );
+        internalEnvironment.setPeripheral( ComputerSide.valueOf( side ), peripheral );
     }
 
     @Deprecated
@@ -238,12 +239,17 @@ public class Computer
     }
 
     @Deprecated
-    @SuppressWarnings( "unused" )
     public void advance( double dt )
     {
         tick();
     }
 
     @Deprecated
-    public static final String[] s_sideNames = IAPIEnvironment.SIDE_NAMES;
+    public IWritableMount getRootMount()
+    {
+        return executor.getRootMount();
+    }
+
+    @Deprecated
+    public static final String[] s_sideNames = ComputerSide.NAMES;
 }

src/main/java/dan200/computercraft/core/computer/ComputerExecutor.java

@@ -268,7 +268,7 @@ final class ComputerExecutor
     }
 
     /**
-     * Queue an event if the computer is on
+     * Queue an event if the computer is on.
      *
      * @param event The event's name
      * @param args  The event's arguments
@@ -338,7 +338,7 @@ final class ComputerExecutor
         }
     }
 
-    private FileSystem createFileSystem()
+    IWritableMount getRootMount()
     {
         if( rootMount == null )
         {
@@ -347,11 +347,15 @@ final class ComputerExecutor
                 computer.getComputerEnvironment().getComputerSpaceLimit()
             );
         }
+        return rootMount;
+    }
 
+    private FileSystem createFileSystem()
+    {
         FileSystem filesystem = null;
         try
         {
-            filesystem = new FileSystem( "hdd", rootMount );
+            filesystem = new FileSystem( "hdd", getRootMount() );
 
             IMount romMount = getRomMount();
             if( romMount == null )

src/main/java/dan200/computercraft/core/computer/ComputerSide.java

@@ -0,0 +1,59 @@
+/*
+ * This file is part of ComputerCraft - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2019. Do not distribute without permission.
+ * Send enquiries to dratcliffe@gmail.com
+ */
+
+package dan200.computercraft.core.computer;
+
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+
+/**
+ * A side on a computer. Unlike {@link net.minecraft.util.EnumFacing}, this is relative to the direction the computer is
+ * facing..
+ */
+public enum ComputerSide
+{
+    BOTTOM( "bottom" ),
+    TOP( "top" ),
+    BACK( "back" ),
+    FRONT( "front" ),
+    RIGHT( "right" ),
+    LEFT( "left" );
+
+    public static final String[] NAMES = new String[] { "bottom", "top", "back", "front", "right", "left" };
+
+    public static final int COUNT = 6;
+
+    private static final ComputerSide[] VALUES = values();
+
+    private final String name;
+
+    ComputerSide( String name )
+    {
+        this.name = name;
+    }
+
+    @Nonnull
+    public static ComputerSide valueOf( int side )
+    {
+        return VALUES[side];
+    }
+
+    @Nullable
+    public static ComputerSide valueOfInsensitive( @Nonnull String name )
+    {
+        for( ComputerSide side : VALUES )
+        {
+            if( side.name.equalsIgnoreCase( name ) ) return side;
+        }
+
+        return null;
+    }
+
+    public String getName()
+    {
+        return name;
+    }
+}

src/main/java/dan200/computercraft/core/computer/ComputerSystem.java

@@ -26,12 +26,12 @@ import javax.annotation.Nullable;
  */
 public class ComputerSystem extends ComputerAccess implements IComputerSystem
 {
-    private final IAPIEnvironment m_environment;
+    private final IAPIEnvironment environment;
 
     ComputerSystem( IAPIEnvironment environment )
     {
         super( environment );
-        this.m_environment = environment;
+        this.environment = environment;
     }
 
     @Nonnull
@@ -45,7 +45,7 @@ public class ComputerSystem extends ComputerAccess implements IComputerSystem
     @Override
     public IFileSystem getFileSystem()
     {
-        FileSystem fs = m_environment.getFileSystem();
+        FileSystem fs = environment.getFileSystem();
         return fs == null ? null : fs.getMountWrapper();
     }
 
@@ -53,6 +53,6 @@ public class ComputerSystem extends ComputerAccess implements IComputerSystem
     @Override
     public String getLabel()
     {
-        return m_environment.getLabel();
+        return environment.getLabel();
     }
 }

src/main/java/dan200/computercraft/core/computer/ComputerThread.java

@@ -50,7 +50,7 @@ import static dan200.computercraft.core.computer.TimeoutState.TIMEOUT;
 public final class ComputerThread
 {
     /**
-     * How often the computer thread monitor should run, in milliseconds
+     * How often the computer thread monitor should run, in milliseconds.
      *
      * @see Monitor
      */
@@ -83,7 +83,7 @@ public final class ComputerThread
     private static final Object threadLock = new Object();
 
     /**
-     * Whether the computer thread system is currently running
+     * Whether the computer thread system is currently running.
      */
     private static volatile boolean running = false;
 
@@ -105,7 +105,7 @@ public final class ComputerThread
     private static final Condition hasWork = computerLock.newCondition();
 
     /**
-     * Active queues to execute
+     * Active queues to execute.
      */
     private static final TreeSet<ComputerExecutor> computerQueue = new TreeSet<>( ( a, b ) -> {
         if( a == b ) return 0; // Should never happen, but let's be consistent here
@@ -126,14 +126,13 @@ public final class ComputerThread
     private ComputerThread() {}
 
     /**
-     * Start the computer thread
+     * Start the computer thread.
      */
     static void start()
     {
         synchronized( threadLock )
         {
             running = true;
-            if( monitor == null || !monitor.isAlive() ) (monitor = monitorFactory.newThread( new Monitor() )).start();
 
             if( runners == null )
             {
@@ -158,6 +157,8 @@ public final class ComputerThread
                     runnerFactory.newThread( runners[i] = new TaskRunner() ).start();
                 }
             }
+
+            if( monitor == null || !monitor.isAlive() ) (monitor = monitorFactory.newThread( new Monitor() )).start();
         }
     }
 
@@ -193,7 +194,7 @@ public final class ComputerThread
     }
 
     /**
-     * Mark a computer as having work, enqueuing it on the thread
+     * Mark a computer as having work, enqueuing it on the thread.
      *
      * You must be holding {@link ComputerExecutor}'s {@code queueLock} when calling this method - it should only
      * be called from {@code enqueue}.
@@ -243,6 +244,8 @@ public final class ComputerThread
      * {@link #minimumVirtualRuntime} based on the current tasks.
      *
      * This is called before queueing tasks, to ensure that {@link #minimumVirtualRuntime} is up-to-date.
+     *
+     * @param current The machine which we updating runtimes from.
      */
     private static void updateRuntimes( @Nullable ComputerExecutor current )
     {
@@ -320,7 +323,7 @@ public final class ComputerThread
     }
 
     /**
-     * The scaled period for a single task
+     * The scaled period for a single task.
      *
      * @return The scaled period for the task
      * @see #DEFAULT_LATENCY
@@ -335,7 +338,7 @@ public final class ComputerThread
     }
 
     /**
-     * Determine if the thread has computers queued up
+     * Determine if the thread has computers queued up.
      *
      * @return If we have work queued up.
      */
@@ -368,7 +371,16 @@ public final class ComputerThread
                         {
                             TaskRunner runner = currentRunners[i];
                             // If we've no runner, skip.
-                            if( runner == null ) continue;
+                            if( runner == null || runner.owner == null || !runner.owner.isAlive() )
+                            {
+                                if( !running ) continue;
+
+                                // Mark the old runner as dead and start a new one.
+                                ComputerCraft.log.warn( "Previous runner ({}) has crashed, restarting!",
+                                    runner != null && runner.owner != null ? runner.owner.getName() : runner );
+                                if( runner != null ) runner.running = false;
+                                runnerFactory.newThread( runners[i] = new TaskRunner() ).start();
+                            }
 
                             // If the runner has no work, skip
                             ComputerExecutor executor = runner.currentExecutor.get();
@@ -492,7 +504,7 @@ public final class ComputerThread
                 {
                     executor.work();
                 }
-                catch( Exception e )
+                catch( Exception | LinkageError | VirtualMachineError e )
                 {
                     ComputerCraft.log.error( "Error running task on computer #" + executor.getComputer().getID(), e );
                 }

src/main/java/dan200/computercraft/core/computer/Environment.java

@@ -41,17 +41,17 @@ public final class Environment implements IAPIEnvironment
     private final Computer computer;
 
     private boolean internalOutputChanged = false;
-    private final int[] internalOutput = new int[SIDE_COUNT];
-    private final int[] internalBundledOutput = new int[SIDE_COUNT];
+    private final int[] internalOutput = new int[ComputerSide.COUNT];
+    private final int[] internalBundledOutput = new int[ComputerSide.COUNT];
 
-    private final int[] externalOutput = new int[SIDE_COUNT];
-    private final int[] externalBundledOutput = new int[SIDE_COUNT];
+    private final int[] externalOutput = new int[ComputerSide.COUNT];
+    private final int[] externalBundledOutput = new int[ComputerSide.COUNT];
 
     private boolean inputChanged = false;
-    private final int[] input = new int[SIDE_COUNT];
-    private final int[] bundledInput = new int[SIDE_COUNT];
+    private final int[] input = new int[ComputerSide.COUNT];
+    private final int[] bundledInput = new int[ComputerSide.COUNT];
 
-    private final IPeripheral[] peripherals = new IPeripheral[SIDE_COUNT];
+    private final IPeripheral[] peripherals = new IPeripheral[ComputerSide.COUNT];
     private IPeripheralChangeListener peripheralListener = null;
 
     Environment( Computer computer )
@@ -111,85 +111,89 @@ public final class Environment implements IAPIEnvironment
     }
 
     @Override
-    public int getInput( int side )
+    public int getInput( ComputerSide side )
     {
-        return input[side];
+        return input[side.ordinal()];
     }
 
     @Override
-    public int getBundledInput( int side )
+    public int getBundledInput( ComputerSide side )
     {
-        return bundledInput[side];
+        return bundledInput[side.ordinal()];
     }
 
     @Override
-    public void setOutput( int side, int output )
+    public void setOutput( ComputerSide side, int output )
     {
+        int index = side.ordinal();
         synchronized( internalOutput )
         {
-            if( internalOutput[side] != output )
+            if( internalOutput[index] != output )
             {
-                internalOutput[side] = output;
+                internalOutput[index] = output;
                 internalOutputChanged = true;
             }
         }
     }
 
     @Override
-    public int getOutput( int side )
+    public int getOutput( ComputerSide side )
     {
         synchronized( internalOutput )
         {
-            return computer.isOn() ? internalOutput[side] : 0;
+            return computer.isOn() ? internalOutput[side.ordinal()] : 0;
         }
     }
 
     @Override
-    public void setBundledOutput( int side, int output )
+    public void setBundledOutput( ComputerSide side, int output )
     {
+        int index = side.ordinal();
         synchronized( internalOutput )
         {
-            if( internalBundledOutput[side] != output )
+            if( internalBundledOutput[index] != output )
             {
-                internalBundledOutput[side] = output;
+                internalBundledOutput[index] = output;
                 internalOutputChanged = true;
             }
         }
     }
 
     @Override
-    public int getBundledOutput( int side )
+    public int getBundledOutput( ComputerSide side )
     {
         synchronized( internalOutput )
         {
-            return computer.isOn() ? internalBundledOutput[side] : 0;
+            return computer.isOn() ? internalBundledOutput[side.ordinal()] : 0;
         }
     }
 
-    public int getExternalRedstoneOutput( int side )
+    public int getExternalRedstoneOutput( ComputerSide side )
     {
-        return computer.isOn() ? externalOutput[side] : 0;
+        return computer.isOn() ? externalOutput[side.ordinal()] : 0;
     }
 
-    public int getExternalBundledRedstoneOutput( int side )
+    public int getExternalBundledRedstoneOutput( ComputerSide side )
     {
-        return computer.isOn() ? externalBundledOutput[side] : 0;
+        return computer.isOn() ? externalBundledOutput[side.ordinal()] : 0;
     }
 
-    public void setRedstoneInput( int side, int level )
+    public void setRedstoneInput( ComputerSide side, int level )
     {
-        if( input[side] != level )
+        int index = side.ordinal();
+        if( input[index] != level )
         {
-            input[side] = level;
+            input[index] = level;
             inputChanged = true;
         }
     }
 
-    public void setBundledRedstoneInput( int side, int combination )
+    public void setBundledRedstoneInput( ComputerSide side, int combination )
     {
-        if( bundledInput[side] != combination )
+        int index = side.ordinal();
+        if( bundledInput[index] != combination )
         {
-            bundledInput[side] = combination;
+            bundledInput[index] = combination;
             inputChanged = true;
         }
     }
@@ -222,7 +226,7 @@ public final class Environment implements IAPIEnvironment
 
             boolean changed = false;
 
-            for( int i = 0; i < SIDE_COUNT; i++ )
+            for( int i = 0; i < ComputerSide.COUNT; i++ )
             {
                 if( externalOutput[i] != internalOutput[i] )
                 {
@@ -255,24 +259,25 @@ public final class Environment implements IAPIEnvironment
     }
 
     @Override
-    public IPeripheral getPeripheral( int side )
+    public IPeripheral getPeripheral( ComputerSide side )
     {
         synchronized( peripherals )
         {
-            return peripherals[side];
+            return peripherals[side.ordinal()];
         }
     }
 
-    public void setPeripheral( int side, IPeripheral peripheral )
+    public void setPeripheral( ComputerSide side, IPeripheral peripheral )
     {
         synchronized( peripherals )
         {
-            IPeripheral existing = peripherals[side];
+            int index = side.ordinal();
+            IPeripheral existing = peripherals[index];
             if( (existing == null && peripheral != null) ||
                 (existing != null && peripheral == null) ||
                 (existing != null && !existing.equals( peripheral )) )
             {
-                peripherals[side] = peripheral;
+                peripherals[index] = peripheral;
                 if( peripheralListener != null ) peripheralListener.onPeripheralChanged( side, peripheral );
             }
         }

src/main/java/dan200/computercraft/core/computer/MainThread.java

@@ -134,7 +134,7 @@ public final class MainThread
         // Of course, we'll go over the MAX_TICK_TIME most of the time, but eventually that overrun will accumulate
         // and we'll skip a whole tick - bringing the average back down again.
         currentTick++;
-        budget += Math.min( budget + ComputerCraft.maxMainGlobalTime, ComputerCraft.maxMainGlobalTime );
+        budget = Math.min( budget + ComputerCraft.maxMainGlobalTime, ComputerCraft.maxMainGlobalTime );
         canExecute = budget > 0;
 
         // Cool down any warm computers.

src/main/java/dan200/computercraft/core/computer/MainThreadExecutor.java

@@ -224,7 +224,7 @@ final class MainThreadExecutor implements IWorkMonitor
     {
         state = State.COOLING;
         currentTick = MainThread.currentTick();
-        budget += Math.min( budget + ComputerCraft.maxMainComputerTime, ComputerCraft.maxMainComputerTime );
+        budget = Math.min( budget + ComputerCraft.maxMainComputerTime, ComputerCraft.maxMainComputerTime );
         if( budget < ComputerCraft.maxMainComputerTime ) return false;
 
         state = State.COOL;

src/main/java/dan200/computercraft/core/computer/TimeoutState.java

@@ -36,12 +36,12 @@ import java.util.concurrent.TimeUnit;
 public final class TimeoutState
 {
     /**
-     * The total time a task is allowed to run before aborting in nanoseconds
+     * The total time a task is allowed to run before aborting in nanoseconds.
      */
     static final long TIMEOUT = TimeUnit.MILLISECONDS.toNanos( 7000 );
 
     /**
-     * The time the task is allowed to run after each abort in nanoseconds
+     * The time the task is allowed to run after each abort in nanoseconds.
      */
     static final long ABORT_TIMEOUT = TimeUnit.MILLISECONDS.toNanos( 1500 );
 
@@ -111,6 +111,8 @@ public final class TimeoutState
 
     /**
      * If the machine should be passively aborted.
+     *
+     * @return {@code true} if we should throw a timeout error.
      */
     public boolean isSoftAborted()
     {
@@ -118,7 +120,9 @@ public final class TimeoutState
     }
 
     /**
-     * If the machine should be forcibly aborted.
+     * Determine if the machine should be forcibly aborted.
+     *
+     * @return {@code true} if the machine should be forcibly shut down.
      */
     public boolean isHardAborted()
     {
@@ -146,7 +150,7 @@ public final class TimeoutState
     }
 
     /**
-     * Pauses the cumulative time, to be resumed by {@link #startTimer()}
+     * Pauses the cumulative time, to be resumed by {@link #startTimer()}.
      *
      * @see #nanoCumulative()
      */

src/main/java/dan200/computercraft/core/filesystem/ComboMount.java

@@ -6,6 +6,7 @@
 
 package dan200.computercraft.core.filesystem;
 
+import dan200.computercraft.api.filesystem.FileOperationException;
 import dan200.computercraft.api.filesystem.IMount;
 
 import javax.annotation.Nonnull;
@@ -95,7 +96,7 @@ public class ComboMount implements IMount
         }
         else
         {
-            throw new IOException( "/" + path + ": Not a directory" );
+            throw new FileOperationException( path, "Not a directory" );
         }
     }
 
@@ -110,7 +111,7 @@ public class ComboMount implements IMount
                 return part.getSize( path );
             }
         }
-        throw new IOException( "/" + path + ": No such file" );
+        throw new FileOperationException( path, "No such file" );
     }
 
     @Nonnull
@@ -126,7 +127,7 @@ public class ComboMount implements IMount
                 return part.openForRead( path );
             }
         }
-        throw new IOException( "/" + path + ": No such file" );
+        throw new FileOperationException( path, "No such file" );
     }
 
     @Nonnull
@@ -141,6 +142,6 @@ public class ComboMount implements IMount
                 return part.openChannelForRead( path );
             }
         }
-        throw new IOException( "/" + path + ": No such file" );
+        throw new FileOperationException( path, "No such file" );
     }
 }

src/main/java/dan200/computercraft/core/filesystem/EmptyMount.java

@@ -6,6 +6,7 @@
 
 package dan200.computercraft.core.filesystem;
 
+import dan200.computercraft.api.filesystem.FileOperationException;
 import dan200.computercraft.api.filesystem.IMount;
 
 import javax.annotation.Nonnull;
@@ -44,7 +45,7 @@ public class EmptyMount implements IMount
     @Deprecated
     public InputStream openForRead( @Nonnull String path ) throws IOException
     {
-        throw new IOException( "/" + path + ": No such file" );
+        throw new FileOperationException( path, "No such file" );
     }
 
     @Nonnull
@@ -52,6 +53,6 @@ public class EmptyMount implements IMount
     @Deprecated
     public ReadableByteChannel openChannelForRead( @Nonnull String path ) throws IOException
     {
-        throw new IOException( "/" + path + ": No such file" );
+        throw new FileOperationException( path, "No such file" );
     }
 }

src/main/java/dan200/computercraft/core/filesystem/FileMount.java

@@ -7,6 +7,7 @@
 package dan200.computercraft.core.filesystem;
 
 import com.google.common.collect.Sets;
+import dan200.computercraft.api.filesystem.FileOperationException;
 import dan200.computercraft.api.filesystem.IWritableMount;
 
 import javax.annotation.Nonnull;
@@ -167,12 +168,12 @@ public class FileMount implements IWritableMount
     {
         if( !created() )
         {
-            if( !path.isEmpty() ) throw new IOException( "/" + path + ": Not a directory" );
+            if( !path.isEmpty() ) throw new FileOperationException( path, "Not a directory" );
             return;
         }
 
         File file = getRealPath( path );
-        if( !file.exists() || !file.isDirectory() ) throw new IOException( "/" + path + ": Not a directory" );
+        if( !file.exists() || !file.isDirectory() ) throw new FileOperationException( path, "Not a directory" );
 
         String[] paths = file.list();
         for( String subPath : paths )
@@ -194,7 +195,7 @@ public class FileMount implements IWritableMount
             if( file.exists() ) return file.isDirectory() ? 0 : file.length();
         }
 
-        throw new IOException( "/" + path + ": No such file" );
+        throw new FileOperationException( path, "No such file" );
     }
 
     @Nonnull
@@ -208,7 +209,7 @@ public class FileMount implements IWritableMount
             if( file.exists() && !file.isDirectory() ) return new FileInputStream( file );
         }
 
-        throw new IOException( "/" + path + ": No such file" );
+        throw new FileOperationException( path, "No such file" );
     }
 
     @Nonnull
@@ -221,7 +222,7 @@ public class FileMount implements IWritableMount
             if( file.exists() && !file.isDirectory() ) return FileChannel.open( file.toPath(), READ_OPTIONS );
         }
 
-        throw new IOException( "/" + path + ": No such file" );
+        throw new FileOperationException( path, "No such file" );
     }
 
     // IWritableMount implementation
@@ -233,7 +234,7 @@ public class FileMount implements IWritableMount
         File file = getRealPath( path );
         if( file.exists() )
         {
-            if( !file.isDirectory() ) throw new IOException( "/" + path + ": File exists" );
+            if( !file.isDirectory() ) throw new FileOperationException( path, "File exists" );
             return;
         }
 
@@ -247,7 +248,7 @@ public class FileMount implements IWritableMount
 
         if( getRemainingSpace() < dirsToCreate * MINIMUM_FILE_SIZE )
         {
-            throw new IOException( "/" + path + ": Out of space" );
+            throw new FileOperationException( path, "Out of space" );
         }
 
         if( file.mkdirs() )
@@ -256,14 +257,14 @@ public class FileMount implements IWritableMount
         }
         else
         {
-            throw new IOException( "/" + path + ": Access denied" );
+            throw new FileOperationException( path, "Access denied" );
         }
     }
 
     @Override
     public void delete( @Nonnull String path ) throws IOException
     {
-        if( path.isEmpty() ) throw new IOException( "/" + path + ": Access denied" );
+        if( path.isEmpty() ) throw new FileOperationException( path, "Access denied" );
 
         if( created() )
         {
@@ -319,7 +320,7 @@ public class FileMount implements IWritableMount
     {
         create();
         File file = getRealPath( path );
-        if( file.exists() && file.isDirectory() ) throw new IOException( "/" + path + ": Cannot write to directory" );
+        if( file.exists() && file.isDirectory() ) throw new FileOperationException( path, "Cannot write to directory" );
 
         if( file.exists() )
         {
@@ -327,7 +328,7 @@ public class FileMount implements IWritableMount
         }
         else if( getRemainingSpace() < MINIMUM_FILE_SIZE )
         {
-            throw new IOException( "/" + path + ": Out of space" );
+            throw new FileOperationException( path, "Out of space" );
         }
         m_usedSpace += MINIMUM_FILE_SIZE;
 
@@ -340,12 +341,12 @@ public class FileMount implements IWritableMount
     {
         if( !created() )
         {
-            throw new IOException( "/" + path + ": No such file" );
+            throw new FileOperationException( path, "No such file" );
         }
 
         File file = getRealPath( path );
-        if( !file.exists() ) throw new IOException( "/" + path + ": No such file" );
-        if( file.isDirectory() ) throw new IOException( "/" + path + ": Cannot write to directory" );
+        if( !file.exists() ) throw new FileOperationException( path, "No such file" );
+        if( file.isDirectory() ) throw new FileOperationException( path, "Cannot write to directory" );
 
         // Allowing seeking when appending is not recommended, so we use a separate channel.
         return new WritableCountingChannel(

src/main/java/dan200/computercraft/core/filesystem/FileSystem.java

@@ -8,6 +8,7 @@ package dan200.computercraft.core.filesystem;
 
 import com.google.common.io.ByteStreams;
 import dan200.computercraft.ComputerCraft;
+import dan200.computercraft.api.filesystem.FileOperationException;
 import dan200.computercraft.api.filesystem.IFileSystem;
 import dan200.computercraft.api.filesystem.IMount;
 import dan200.computercraft.api.filesystem.IWritableMount;
@@ -45,7 +46,7 @@ public class FileSystem
             m_writableMount = null;
         }
 
-        public MountWrapper( String label, String location, IWritableMount mount )
+        MountWrapper( String label, String location, IWritableMount mount )
         {
             this( label, location, (IMount) mount );
             m_writableMount = mount;
@@ -107,7 +108,7 @@ public class FileSystem
             }
             catch( IOException e )
             {
-                throw new FileSystemException( e.getMessage() );
+                throw localExceptionOf( e );
             }
         }
 
@@ -122,12 +123,12 @@ public class FileSystem
                 }
                 else
                 {
-                    throw new FileSystemException( "/" + path + ": Not a directory" );
+                    throw localExceptionOf( path, "Not a directory" );
                 }
             }
             catch( IOException e )
             {
-                throw new FileSystemException( e.getMessage() );
+                throw localExceptionOf( e );
             }
         }
 
@@ -149,12 +150,12 @@ public class FileSystem
                 }
                 else
                 {
-                    throw new FileSystemException( "/" + path + ": No such file" );
+                    throw localExceptionOf( path, "No such file" );
                 }
             }
             catch( IOException e )
             {
-                throw new FileSystemException( e.getMessage() );
+                throw localExceptionOf( e );
             }
         }
 
@@ -169,12 +170,12 @@ public class FileSystem
                 }
                 else
                 {
-                    throw new FileSystemException( "/" + path + ": No such file" );
+                    throw localExceptionOf( path, "No such file" );
                 }
             }
             catch( IOException e )
             {
-                throw new FileSystemException( e.getMessage() );
+                throw localExceptionOf( e );
             }
         }
 
@@ -182,19 +183,14 @@ public class FileSystem
 
         public void makeDirectory( String path ) throws FileSystemException
         {
-            if( m_writableMount == null )
-            {
-                throw new FileSystemException( "/" + path + ": Access denied" );
-            }
+            if( m_writableMount == null ) throw exceptionOf( path, "Access denied" );
+
+            path = toLocal( path );
             try
             {
-                path = toLocal( path );
                 if( m_mount.exists( path ) )
                 {
-                    if( !m_mount.isDirectory( path ) )
-                    {
-                        throw new FileSystemException( "/" + path + ": File exists" );
-                    }
+                    if( !m_mount.isDirectory( path ) ) throw localExceptionOf( path, "File exists" );
                 }
                 else
                 {
@@ -203,16 +199,14 @@ public class FileSystem
             }
             catch( IOException e )
             {
-                throw new FileSystemException( e.getMessage() );
+                throw localExceptionOf( e );
             }
         }
 
         public void delete( String path ) throws FileSystemException
         {
-            if( m_writableMount == null )
-            {
-                throw new FileSystemException( "/" + path + ": Access denied" );
-            }
+            if( m_writableMount == null ) throw exceptionOf( path, "Access denied" );
+
             try
             {
                 path = toLocal( path );
@@ -227,22 +221,20 @@ public class FileSystem
             }
             catch( IOException e )
             {
-                throw new FileSystemException( e.getMessage() );
+                throw localExceptionOf( e );
             }
         }
 
         public WritableByteChannel openForWrite( String path ) throws FileSystemException
         {
-            if( m_writableMount == null )
-            {
-                throw new FileSystemException( "/" + path + ": Access denied" );
-            }
+            if( m_writableMount == null ) throw exceptionOf( path, "Access denied" );
+
+            path = toLocal( path );
             try
             {
-                path = toLocal( path );
                 if( m_mount.exists( path ) && m_mount.isDirectory( path ) )
                 {
-                    throw new FileSystemException( "/" + path + ": Cannot write to directory" );
+                    throw localExceptionOf( path, "Cannot write to directory" );
                 }
                 else
                 {
@@ -263,19 +255,17 @@ public class FileSystem
             }
             catch( IOException e )
             {
-                throw new FileSystemException( e.getMessage() );
+                throw localExceptionOf( e );
             }
         }
 
         public WritableByteChannel openForAppend( String path ) throws FileSystemException
         {
-            if( m_writableMount == null )
-            {
-                throw new FileSystemException( "/" + path + ": Access denied" );
-            }
+            if( m_writableMount == null ) throw exceptionOf( path, "Access denied" );
+
+            path = toLocal( path );
             try
             {
-                path = toLocal( path );
                 if( !m_mount.exists( path ) )
                 {
                     if( !path.isEmpty() )
@@ -290,7 +280,7 @@ public class FileSystem
                 }
                 else if( m_mount.isDirectory( path ) )
                 {
-                    throw new FileSystemException( "/" + path + ": Cannot write to directory" );
+                    throw localExceptionOf( path, "Cannot write to directory" );
                 }
                 else
                 {
@@ -303,16 +293,36 @@ public class FileSystem
             }
             catch( IOException e )
             {
-                throw new FileSystemException( e.getMessage() );
+                throw localExceptionOf( e );
             }
         }
 
-        // private members
-
         private String toLocal( String path )
         {
             return FileSystem.toLocal( path, m_location );
         }
+
+        private FileSystemException localExceptionOf( IOException e )
+        {
+            if( !m_location.isEmpty() && e instanceof FileOperationException )
+            {
+                FileOperationException ex = (FileOperationException) e;
+                if( ex.getFilename() != null ) return localExceptionOf( ex.getFilename(), ex.getMessage() );
+            }
+
+            return new FileSystemException( e.getMessage() );
+        }
+
+        private FileSystemException localExceptionOf( String path, String message )
+        {
+            if( !m_location.isEmpty() ) path = path.isEmpty() ? m_location : m_location + "/" + path;
+            return exceptionOf( path, message );
+        }
+
+        private static FileSystemException exceptionOf( String path, String message )
+        {
+            return new FileSystemException( "/" + path + ": " + message );
+        }
     }
 
     private final FileSystemWrapperMount m_wrapper = new FileSystemWrapperMount( this );
@@ -769,7 +779,7 @@ public class FileSystem
 
         // Clean the path or illegal characters.
         final char[] specialChars = new char[] {
-            '"', ':', '<', '>', '?', '|' // Sorted by ascii value (important)
+            '"', ':', '<', '>', '?', '|', // Sorted by ascii value (important)
         };
 
         StringBuilder cleanName = new StringBuilder();

src/main/java/dan200/computercraft/core/filesystem/JarMount.java

@@ -9,6 +9,7 @@ package dan200.computercraft.core.filesystem;
 import com.google.common.cache.Cache;
 import com.google.common.cache.CacheBuilder;
 import com.google.common.io.ByteStreams;
+import dan200.computercraft.api.filesystem.FileOperationException;
 import dan200.computercraft.api.filesystem.IMount;
 import dan200.computercraft.core.apis.handles.ArrayByteChannel;
 import dan200.computercraft.shared.util.IoUtil;
@@ -69,7 +70,7 @@ public class JarMount implements IMount
         // Cleanup any old mounts. It's unlikely that there will be any, but it's best to be safe.
         cleanup();
 
-        if( !jarFile.exists() || jarFile.isDirectory() ) throw new FileNotFoundException();
+        if( !jarFile.exists() || jarFile.isDirectory() ) throw new FileNotFoundException( "Cannot find " + jarFile );
 
         // Open the zip file
         try
@@ -85,14 +86,14 @@ public class JarMount implements IMount
         if( zip.getEntry( subPath ) == null )
         {
             zip.close();
-            throw new IOException( "Zip does not contain path" );
+            throw new FileNotFoundException( "Zip does not contain path" );
         }
 
         // We now create a weak reference to this mount. This is automatically added to the appropriate queue.
         new MountReference( this );
 
         // Read in all the entries
-        root = new FileEntry( "" );
+        root = new FileEntry();
         Enumeration<? extends ZipEntry> zipEntries = zip.entries();
         while( zipEntries.hasMoreElements() )
         {
@@ -139,7 +140,7 @@ public class JarMount implements IMount
             FileEntry nextEntry = lastEntry.children.get( part );
             if( nextEntry == null || !nextEntry.isDirectory() )
             {
-                lastEntry.children.put( part, nextEntry = new FileEntry( part ) );
+                lastEntry.children.put( part, nextEntry = new FileEntry() );
             }
 
             lastEntry = nextEntry;
@@ -166,7 +167,7 @@ public class JarMount implements IMount
     public void list( @Nonnull String path, @Nonnull List<String> contents ) throws IOException
     {
         FileEntry file = get( path );
-        if( file == null || !file.isDirectory() ) throw new IOException( "/" + path + ": Not a directory" );
+        if( file == null || !file.isDirectory() ) throw new FileOperationException( path, "Not a directory" );
 
         file.list( contents );
     }
@@ -176,7 +177,7 @@ public class JarMount implements IMount
     {
         FileEntry file = get( path );
         if( file != null ) return file.size;
-        throw new IOException( "/" + path + ": No such file" );
+        throw new FileOperationException( path, "No such file" );
     }
 
     @Nonnull
@@ -218,22 +219,15 @@ public class JarMount implements IMount
             }
         }
 
-        throw new IOException( "/" + path + ": No such file" );
+        throw new FileOperationException( path, "No such file" );
     }
 
     private static class FileEntry
     {
-        final String name;
-
         String path;
         long size;
         Map<String, FileEntry> children;
 
-        FileEntry( String name )
-        {
-            this.name = name;
-        }
-
         void setup( ZipEntry entry )
         {
             path = entry.getName();

src/main/java/dan200/computercraft/core/lua/CobaltLuaMachine.java

@@ -242,7 +242,7 @@ public class CobaltLuaMachine implements ILuaMachine
                         }
                         catch( InterruptedException e )
                         {
-                            throw new OrphanedThread();
+                            throw new InterruptedError( e );
                         }
                         catch( LuaException e )
                         {
@@ -550,7 +550,7 @@ public class CobaltLuaMachine implements ILuaMachine
                 {
                     if( ComputerCraft.logPeripheralErrors ) ComputerCraft.log.error( "Error running task", t );
                     m_computer.queueEvent( "task_complete", new Object[] {
-                        taskID, false, "Java Exception Thrown: " + t
+                        taskID, false, "Java Exception Thrown: " + t,
                     } );
                 }
             };

src/main/java/dan200/computercraft/core/lua/MachineResult.java

@@ -38,7 +38,7 @@ public final class MachineResult
     public static final MachineResult TIMEOUT = new MachineResult( true, false, TimeoutState.ABORT_MESSAGE );
 
     /**
-     * An error with no user-friendly error message
+     * An error with no user-friendly error message.
      */
     public static final MachineResult GENERIC_ERROR = new MachineResult( true, false, null );
 

src/main/java/dan200/computercraft/core/terminal/Terminal.java

@@ -314,6 +314,9 @@ public class Terminal
     }
 
     /**
+     * Determine whether this terminal has changed.
+     *
+     * @return If this terminal is dirty.
      * @deprecated All {@code *Changed()} methods are deprecated: one should pass in a callback
      * instead.
      */

src/main/java/dan200/computercraft/core/terminal/TextBuffer.java

@@ -8,7 +8,7 @@ package dan200.computercraft.core.terminal;
 
 public class TextBuffer
 {
-    public char[] m_text;
+    private final char[] m_text;
 
     public TextBuffer( char c, int length )
     {

src/main/java/dan200/computercraft/shared/BundledRedstone.java

@@ -6,7 +6,6 @@
 
 package dan200.computercraft.shared;
 
-import com.google.common.base.Preconditions;
 import dan200.computercraft.ComputerCraft;
 import dan200.computercraft.api.redstone.IBundledRedstoneProvider;
 import dan200.computercraft.shared.common.DefaultBundledRedstoneProvider;
@@ -16,6 +15,7 @@ import net.minecraft.world.World;
 
 import javax.annotation.Nonnull;
 import java.util.LinkedHashSet;
+import java.util.Objects;
 import java.util.Set;
 
 public final class BundledRedstone
@@ -26,7 +26,7 @@ public final class BundledRedstone
 
     public static void register( @Nonnull IBundledRedstoneProvider provider )
     {
-        Preconditions.checkNotNull( provider, "provider cannot be null" );
+        Objects.requireNonNull( provider, "provider cannot be null" );
         providers.add( provider );
     }
 

src/main/java/dan200/computercraft/shared/Config.java

@@ -54,8 +54,8 @@ public final class Config
 
     private static Property httpEnable;
     private static Property httpWebsocketEnable;
-    private static Property httpWhitelist;
-    private static Property httpBlacklist;
+    private static Property httpAllowedDomains;
+    private static Property httpBlockedDomains;
 
     private static Property httpTimeout;
     private static Property httpMaxRequests;
@@ -163,30 +163,32 @@ public final class Config
         { // HTTP
             renameProperty( CATEGORY_GENERAL, "http_enable", CATEGORY_HTTP, "enabled" );
             renameProperty( CATEGORY_GENERAL, "http_websocket_enable", CATEGORY_HTTP, "websocket_enabled" );
-            renameProperty( CATEGORY_GENERAL, "http_whitelist", CATEGORY_HTTP, "whitelist" );
-            renameProperty( CATEGORY_GENERAL, "http_blacklist", CATEGORY_HTTP, "blacklist" );
+            renameProperty( CATEGORY_GENERAL, "http_whitelist", CATEGORY_HTTP, "allowed_domains" );
+            renameProperty( CATEGORY_GENERAL, "http_blacklist", CATEGORY_HTTP, "blocked_domains" );
+            renameProperty( CATEGORY_HTTP, "whitelist", CATEGORY_HTTP, "allowed_domains" );
+            renameProperty( CATEGORY_HTTP, "blacklist", CATEGORY_HTTP, "blocked_domains" );
 
             config.getCategory( CATEGORY_HTTP )
                 .setComment( "Controls the HTTP API" );
 
             httpEnable = config.get( CATEGORY_HTTP, "enabled", ComputerCraft.http_enable );
-            httpEnable.setComment( "Enable the \"http\" API on Computers (see \"http_whitelist\" and \"http_blacklist\" for " +
-                "more fine grained control than this)" );
+            httpEnable.setComment( "Enable the \"http\" API on Computers (see \"allowed_domains\" and \"blocked_domains\" " +
+                "for more fine grained control than this)" );
 
             httpWebsocketEnable = config.get( CATEGORY_HTTP, "websocket_enabled", ComputerCraft.http_websocket_enable );
             httpWebsocketEnable.setComment( "Enable use of http websockets. This requires the \"http_enable\" option to also be true." );
 
-            httpWhitelist = config.get( CATEGORY_HTTP, "whitelist", DEFAULT_HTTP_WHITELIST );
-            httpWhitelist.setComment( "A list of wildcards for domains or IP ranges that can be accessed through the " +
+            httpAllowedDomains = config.get( CATEGORY_HTTP, "allowed_domains", DEFAULT_HTTP_WHITELIST );
+            httpAllowedDomains.setComment( "A list of wildcards for domains or IP ranges that can be accessed through the " +
                 "\"http\" API on Computers.\n" +
                 "Set this to \"*\" to access to the entire internet. Example: \"*.pastebin.com\" will restrict access to " +
                 "just subdomains of pastebin.com.\n" +
                 "You can use domain names (\"pastebin.com\"), wilcards (\"*.pastebin.com\") or CIDR notation (\"127.0.0.0/8\")." );
 
-            httpBlacklist = config.get( CATEGORY_HTTP, "blacklist", DEFAULT_HTTP_BLACKLIST );
-            httpBlacklist.setComment( "A list of wildcards for domains or IP ranges that cannot be accessed through the " +
+            httpBlockedDomains = config.get( CATEGORY_HTTP, "blocked_domains", DEFAULT_HTTP_BLACKLIST );
+            httpBlockedDomains.setComment( "A list of wildcards for domains or IP ranges that cannot be accessed through the " +
                 "\"http\" API on Computers.\n" +
-                "If this is empty then all whitelisted domains will be accessible. Example: \"*.github.com\" will block " +
+                "If this is empty then all explicitly allowed domains will be accessible. Example: \"*.github.com\" will block " +
                 "access to all subdomains of github.com.\n" +
                 "You can use domain names (\"pastebin.com\"), wilcards (\"*.pastebin.com\") or CIDR notation (\"127.0.0.0/8\")." );
 
@@ -220,7 +222,7 @@ public final class Config
 
             setOrder(
                 CATEGORY_HTTP,
-                httpEnable, httpWebsocketEnable, httpWhitelist, httpBlacklist,
+                httpEnable, httpWebsocketEnable, httpAllowedDomains, httpBlockedDomains,
                 httpTimeout, httpMaxRequests, httpMaxDownload, httpMaxUpload, httpMaxWebsockets, httpMaxWebsocketMessage
             );
         }
@@ -277,7 +279,7 @@ public final class Config
             renameProperty( CATEGORY_GENERAL, "turtlesCanPush", CATEGORY_TURTLE, "can_push" );
             renameProperty( CATEGORY_GENERAL, "turtle_disabled_actions", CATEGORY_TURTLE, "disabled_actions" );
 
-            config.getCategory( CATEGORY_HTTP )
+            config.getCategory( CATEGORY_TURTLE )
                 .setComment( "Various options relating to turtles." );
 
             turtlesNeedFuel = config.get( CATEGORY_TURTLE, "need_fuel", ComputerCraft.turtlesNeedFuel );
@@ -402,7 +404,7 @@ public final class Config
 
             if( oldProperty.isList() )
             {
-                oldProperty.setValues( oldProperty.getStringList() );
+                oldProperty.setValues( newProperty.getStringList() );
             }
             else
             {
@@ -441,8 +443,8 @@ public final class Config
         // HTTP
         ComputerCraft.http_enable = httpEnable.getBoolean();
         ComputerCraft.http_websocket_enable = httpWebsocketEnable.getBoolean();
-        ComputerCraft.http_whitelist = new AddressPredicate( httpWhitelist.getStringList() );
-        ComputerCraft.http_blacklist = new AddressPredicate( httpBlacklist.getStringList() );
+        ComputerCraft.http_whitelist = new AddressPredicate( httpAllowedDomains.getStringList() );
+        ComputerCraft.http_blacklist = new AddressPredicate( httpBlockedDomains.getStringList() );
 
         ComputerCraft.httpTimeout = Math.max( 0, httpTimeout.getInt() );
         ComputerCraft.httpMaxRequests = Math.max( 1, httpMaxRequests.getInt() );

src/main/java/dan200/computercraft/shared/TurtlePermissions.java

@@ -6,7 +6,6 @@
 
 package dan200.computercraft.shared;
 
-import com.google.common.base.Preconditions;
 import dan200.computercraft.ComputerCraft;
 import dan200.computercraft.api.permissions.ITurtlePermissionProvider;
 import dan200.computercraft.api.turtle.event.TurtleActionEvent;
@@ -20,6 +19,7 @@ import net.minecraftforge.fml.common.eventhandler.SubscribeEvent;
 import javax.annotation.Nonnull;
 import java.util.Collection;
 import java.util.LinkedHashSet;
+import java.util.Objects;
 
 @Mod.EventBusSubscriber( modid = ComputerCraft.MOD_ID )
 public final class TurtlePermissions
@@ -32,7 +32,7 @@ public final class TurtlePermissions
 
     public static void register( @Nonnull ITurtlePermissionProvider upgrade )
     {
-        Preconditions.checkNotNull( upgrade, "upgrade cannot be null" );
+        Objects.requireNonNull( upgrade, "upgrade cannot be null" );
 
         providers.add( upgrade );
     }

src/main/java/dan200/computercraft/shared/TurtleUpgrades.java

@@ -19,12 +19,35 @@ import net.minecraftforge.fml.common.ModContainer;
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 import java.util.*;
+import java.util.stream.Stream;
 
 public final class TurtleUpgrades
 {
+    public static class Wrapper
+    {
+        final ITurtleUpgrade upgrade;
+        final int legacyId;
+        final String id;
+        final String modId;
+        boolean enabled;
+
+        public Wrapper( ITurtleUpgrade upgrade )
+        {
+            ModContainer mc = Loader.instance().activeModContainer();
+
+            this.upgrade = upgrade;
+            this.legacyId = upgrade.getLegacyUpgradeID();
+            this.id = upgrade.getUpgradeID().toString();
+            this.modId = mc != null && mc.getModId() != null ? mc.getModId() : null;
+            this.enabled = true;
+        }
+    }
+
+    private static ITurtleUpgrade[] vanilla;
+
     private static final Map<String, ITurtleUpgrade> upgrades = new HashMap<>();
     private static final Int2ObjectMap<ITurtleUpgrade> legacyUpgrades = new Int2ObjectOpenHashMap<>();
-    private static final IdentityHashMap<ITurtleUpgrade, String> upgradeOwners = new IdentityHashMap<>();
+    private static final IdentityHashMap<ITurtleUpgrade, Wrapper> wrappers = new IdentityHashMap<>();
 
     private TurtleUpgrades() {}
 
@@ -35,9 +58,7 @@ public final class TurtleUpgrades
         int id = upgrade.getLegacyUpgradeID();
         if( id >= 0 && id < 64 )
         {
-            String message = getMessage( upgrade, "Legacy UpgradeID '" + id + "' is reserved by ComputerCraft" );
-            ComputerCraft.log.error( message );
-            throw new RuntimeException( message );
+            throw registrationError( upgrade, "Legacy Upgrade ID '" + id + "' is reserved by ComputerCraft" );
         }
 
         registerInternal( upgrade );
@@ -47,58 +68,63 @@ public final class TurtleUpgrades
     {
         Objects.requireNonNull( upgrade, "upgrade cannot be null" );
 
+        Wrapper wrapper = new Wrapper( upgrade );
+
         // Check conditions
-        int legacyId = upgrade.getLegacyUpgradeID();
+        int legacyId = wrapper.legacyId;
         if( legacyId >= 0 )
         {
             if( legacyId >= Short.MAX_VALUE )
             {
-                String message = getMessage( upgrade, "UpgradeID '" + legacyId + "' is out of range" );
-                ComputerCraft.log.error( message );
-                throw new RuntimeException( message );
+                throw registrationError( upgrade, "Upgrade ID '" + legacyId + "' is out of range" );
             }
 
             ITurtleUpgrade existing = legacyUpgrades.get( legacyId );
             if( existing != null )
             {
-                String message = getMessage( upgrade, "UpgradeID '" + legacyId + "' is already registered by '" + existing.getUnlocalisedAdjective() + " Turtle'" );
-                ComputerCraft.log.error( message );
-                throw new RuntimeException( message );
+                throw registrationError( upgrade, "Upgrade ID '" + legacyId + "' is already registered by '" + existing.getUnlocalisedAdjective() + " Turtle'" );
             }
         }
 
-        String id = upgrade.getUpgradeID().toString();
+        String id = wrapper.id;
         ITurtleUpgrade existing = upgrades.get( id );
         if( existing != null )
         {
-            String message = getMessage( upgrade, "UpgradeID '" + id + "' is already registered by '" + existing.getUnlocalisedAdjective() + " Turtle'" );
-            ComputerCraft.log.error( message );
-            throw new RuntimeException( message );
+            throw registrationError( upgrade, "Upgrade '" + id + "' is already registered by '" + existing.getUnlocalisedAdjective() + " Turtle'" );
         }
 
         // Register
         if( legacyId >= 0 ) legacyUpgrades.put( legacyId, upgrade );
         upgrades.put( id, upgrade );
-
-        ModContainer mc = Loader.instance().activeModContainer();
-        if( mc != null && mc.getModId() != null ) upgradeOwners.put( upgrade, mc.getModId() );
+        wrappers.put( upgrade, wrapper );
     }
 
-    private static String getMessage( ITurtleUpgrade upgrade, String rest )
+    private static RuntimeException registrationError( ITurtleUpgrade upgrade, String rest )
     {
-        return "Error registering '" + upgrade.getUnlocalisedAdjective() + " Turtle'. " + rest;
+        String message = "Error registering '" + upgrade.getUnlocalisedAdjective() + " Turtle'. " + rest;
+        ComputerCraft.log.error( message );
+        throw new IllegalArgumentException( message );
     }
 
+    @Nullable
     public static ITurtleUpgrade get( String id )
     {
         return upgrades.get( id );
     }
 
+    @Nullable
     public static ITurtleUpgrade get( int id )
     {
         return legacyUpgrades.get( id );
     }
 
+    @Nullable
+    public static String getOwner( @Nonnull ITurtleUpgrade upgrade )
+    {
+        Wrapper wrapper = wrappers.get( upgrade );
+        return wrapper != null ? wrapper.modId : null;
+    }
+
     public static ITurtleUpgrade get( @Nonnull ItemStack stack )
     {
         if( stack.isEmpty() ) return null;
@@ -115,25 +141,24 @@ public final class TurtleUpgrades
         return null;
     }
 
-    public static Iterable<ITurtleUpgrade> getVanillaUpgrades()
+    public static Stream<ITurtleUpgrade> getVanillaUpgrades()
     {
-        List<ITurtleUpgrade> vanilla = new ArrayList<>();
-        vanilla.add( ComputerCraft.TurtleUpgrades.diamondPickaxe );
-        vanilla.add( ComputerCraft.TurtleUpgrades.diamondAxe );
-        vanilla.add( ComputerCraft.TurtleUpgrades.diamondSword );
-        vanilla.add( ComputerCraft.TurtleUpgrades.diamondShovel );
-        vanilla.add( ComputerCraft.TurtleUpgrades.diamondHoe );
-        vanilla.add( ComputerCraft.TurtleUpgrades.craftingTable );
-        vanilla.add( ComputerCraft.TurtleUpgrades.wirelessModem );
-        vanilla.add( ComputerCraft.TurtleUpgrades.advancedModem );
-        vanilla.add( ComputerCraft.TurtleUpgrades.speaker );
-        return vanilla;
-    }
+        if( vanilla == null )
+        {
+            vanilla = new ITurtleUpgrade[] {
+                ComputerCraft.TurtleUpgrades.diamondPickaxe,
+                ComputerCraft.TurtleUpgrades.diamondAxe,
+                ComputerCraft.TurtleUpgrades.diamondSword,
+                ComputerCraft.TurtleUpgrades.diamondShovel,
+                ComputerCraft.TurtleUpgrades.diamondHoe,
+                ComputerCraft.TurtleUpgrades.craftingTable,
+                ComputerCraft.TurtleUpgrades.wirelessModem,
+                ComputerCraft.TurtleUpgrades.advancedModem,
+                ComputerCraft.TurtleUpgrades.speaker,
+            };
+        }
 
-    @Nullable
-    public static String getOwner( @Nonnull ITurtleUpgrade upgrade )
-    {
-        return upgradeOwners.get( upgrade );
+        return Arrays.stream( vanilla ).filter( x -> x != null && wrappers.get( x ).enabled );
     }
 
     public static Iterable<ITurtleUpgrade> getUpgrades()
@@ -145,4 +170,14 @@ public final class TurtleUpgrades
     {
         return true;
     }
+
+    public static void disable( ITurtleUpgrade upgrade )
+    {
+        Wrapper wrapper = wrappers.get( upgrade );
+        if( !wrapper.enabled ) return;
+
+        wrapper.enabled = false;
+        upgrades.remove( wrapper.id );
+        if( wrapper.legacyId >= 0 ) legacyUpgrades.remove( wrapper.legacyId );
+    }
 }

src/main/java/dan200/computercraft/shared/command/CommandComputerCraft.java

@@ -9,8 +9,8 @@ package dan200.computercraft.shared.command;
 import com.google.common.collect.Sets;
 import dan200.computercraft.ComputerCraft;
 import dan200.computercraft.api.peripheral.IPeripheral;
-import dan200.computercraft.core.apis.IAPIEnvironment;
 import dan200.computercraft.core.computer.Computer;
+import dan200.computercraft.core.computer.ComputerSide;
 import dan200.computercraft.core.tracking.ComputerTracker;
 import dan200.computercraft.core.tracking.Tracking;
 import dan200.computercraft.core.tracking.TrackingContext;
@@ -115,12 +115,12 @@ public final class CommandComputerCraft extends CommandDelegate
                     table.row( header( "Position" ), linkPosition( context, computer ) );
                     table.row( header( "Family" ), text( computer.getFamily().toString() ) );
 
-                    for( int i = 0; i < 6; i++ )
+                    for( ComputerSide side : ComputerSide.values() )
                     {
-                        IPeripheral peripheral = computer.getPeripheral( i );
+                        IPeripheral peripheral = computer.getPeripheral( side );
                         if( peripheral != null )
                         {
-                            table.row( header( "Peripheral " + IAPIEnvironment.SIDE_NAMES[i] ), text( peripheral.getType() ) );
+                            table.row( header( "Peripheral " + side.getName() ), text( peripheral.getType() ) );
                         }
                     }
 

src/main/java/dan200/computercraft/shared/command/framework/CommandRoot.java

@@ -18,7 +18,7 @@ import java.util.List;
 import java.util.Map;
 
 /**
- * A command which delegates to a series of sub commands
+ * A command which delegates to a series of sub commands.
  */
 public class CommandRoot implements ISubCommand
 {

src/main/java/dan200/computercraft/shared/command/framework/ISubCommand.java

@@ -22,7 +22,7 @@ import java.util.List;
 public interface ISubCommand
 {
     /**
-     * Get the name of this command
+     * Get the name of this command.
      *
      * @return The name of this command
      * @see ICommand#getName()
@@ -40,7 +40,7 @@ public interface ISubCommand
     String getFullName();
 
     /**
-     * Get the usage of this command
+     * Get the usage of this command.
      *
      * @param context The context this command is executed in
      * @return The usage of this command
@@ -62,16 +62,17 @@ public interface ISubCommand
     boolean checkPermission( @Nonnull CommandContext context );
 
     /**
-     * Execute this command
+     * Execute this command.
      *
      * @param context   The current command context.
-     * @param arguments The arguments passed  @throws CommandException When an error occurs
+     * @param arguments The arguments passed
+     * @throws CommandException When an error occurs
      * @see ICommand#execute(MinecraftServer, ICommandSender, String[])
      */
     void execute( @Nonnull CommandContext context, @Nonnull List<String> arguments ) throws CommandException;
 
     /**
-     * Get a list of possible completions
+     * Get a list of possible completions.
      *
      * @param context   The current command context.
      * @param arguments The arguments passed. You should complete the last one.