Bump version

Previously we were just returning the current tile. However, if someone
was holding a reference to this inventory (such as a GUI), then it'd be
outdated and invalid once the turtle had moved.

This caused a couple of issues:
 - turtle_inventory events would not be fired when moving items in the
   turtle GUI.
 - As of 75e2845c01, turtles would no
   longer share their inventory state after moving. Thus, removing items
   from a GUI using an invalid inventory would move them from an old
   tile, duplicating the items.

Fixes #298, fixes #300

.github/workflows/main-ci.yml

@@ -0,0 +1,18 @@
+name: Build
+
+on: [push, pull_request]
+
+jobs:
+  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

.gitignore

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

.luacheckrc

@@ -17,7 +17,8 @@ ignore = {
 -- are largely unsupported.
 include_files = {
     'src/main/resources/assets/computercraft/lua/rom',
-    'src/main/resources/assets/computercraft/lua/bios.lua'
+    'src/main/resources/assets/computercraft/lua/bios.lua',
+    'src/test/resources/test-rom',
 }
 
 files['src/main/resources/assets/computercraft/lua/bios.lua'] = {

.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)
-[![Current build status](https://travis-ci.org/SquidDev-CC/CC-Tweaked.svg?branch=master)](https://travis-ci.org/SquidDev-CC/CC-Tweaked "Current build status") [![Download CC: Tweaked on CurseForge](https://cf.way2muchnoise.eu/title/cc-tweaked.svg)](https://minecraft.curseforge.com/projects/cc-tweaked "Download CC: Tweaked on CurseForge")
+[![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.

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 +17,9 @@ buildscript {
 }
 
 plugins {
-    id 'com.matthewprenger.cursegradle' version '1.2.0'
+    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"
 }
 
@@ -43,7 +45,7 @@ minecraft {
 repositories {
     maven {
         name "JEI"
-        url "http://dvs1.progwml6.com/files/maven"
+        url "https://dvs1.progwml6.com/files/maven"
     }
     maven {
         name "SquidDev"
@@ -55,7 +57,7 @@ repositories {
     }
     maven {
         name "Amadornes"
-        url "http://maven.amadornes.com/"
+        url "https://maven.amadornes.com/"
     }
 }
 
@@ -66,6 +68,8 @@ configurations {
 }
 
 dependencies {
+    checkstyle "com.puppycrawl.tools:checkstyle:8.21"
+
     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"
@@ -74,12 +78,14 @@ dependencies {
 
     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"
 }
@@ -98,12 +104,22 @@ 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
 
@@ -199,6 +215,7 @@ 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) {
@@ -226,6 +243,56 @@ 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"
@@ -265,7 +332,6 @@ task checkRelease {
     }
 }
 
-
 curseforge {
     apiKey = project.hasProperty('curseForgeApiKey') ? project.curseForgeApiKey : ''
     project {
@@ -357,18 +423,5 @@ task uploadAll(dependsOn: uploadTasks) {
     description "Uploads to all repositories (Maven, Curse, GitHub release)"
 }
 
-test {
-    useJUnitPlatform()
-    testLogging {
-        events "passed", "skipped", "failed"
-    }
-}
-
-gradle.projectsEvaluated {
-    tasks.withType(JavaCompile) {
-        options.compilerArgs << "-Xlint" << "-Xlint:-processing" << "-Werror"
-    }
-}
-
 runClient.outputs.upToDateWhen { false }
 runServer.outputs.upToDateWhen { false }

config/checkstyle/checkstyle.xml

@@ -0,0 +1,159 @@
+<?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">
+            <property name="skipNoJavadoc" value="true" />
+        </module>
+        <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" />
+
+        <!-- Imports -->
+        <module name="CustomImportOrder" />
+        <module name="IllegalImport" />
+        <module name="RedundantImport" />
+        <module name="UnusedImports" />
+
+        <!-- Javadoc -->
+        <module name="AtclauseOrder" />
+        <!-- TODO: Cleanup our documentation before enabling JavadocMethod, JavadocStyle, JavadocType and SummaryJavadoc. -->
+        <module name="NonEmptyAtclauseDescription" />
+        <module name="SingleLineJavadoc" />
+
+        <!-- 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>
+

config/checkstyle/suppressions.xml

@@ -0,0 +1,9 @@
+<?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" />
+</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=1.83.1
+mod_version=1.85.0
 
 # Minecraft properties
 mc_version=1.12.2

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
@@ -434,28 +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( FileNotFoundException ignored )
-                {
-                }
-                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

@@ -438,45 +438,45 @@ 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

@@ -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/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/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/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/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/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/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/core/apis/FSAPI.java

@@ -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

@@ -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 )
@@ -95,7 +94,7 @@ public class HTTPAPI implements ILuaAPI
 
                 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 );

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/OSAPI.java

@@ -36,9 +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;
         }
@@ -46,10 +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;
@@ -78,9 +78,7 @@ public class OSAPI implements ILuaAPI
     @Override
     public String[] getNames()
     {
-        return new String[] {
-            "os"
-        };
+        return new String[] { "os" };
     }
 
     @Override
@@ -385,9 +383,7 @@ 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" );
@@ -401,7 +397,6 @@ public class OSAPI implements ILuaAPI
                 Instant instant = Instant.ofEpochSecond( time );
                 ZonedDateTime date;
                 ZoneOffset offset;
-                boolean isDst;
                 if( format.startsWith( "!" ) )
                 {
                     offset = ZoneOffset.UTC;

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

@@ -36,7 +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;
@@ -282,9 +282,7 @@ public class PeripheralAPI implements ILuaAPI, IAPIEnvironment.IPeripheralChange
     @Override
     public String[] getNames()
     {
-        return new String[] {
-            "peripheral"
-        };
+        return new String[] { "peripheral" };
     }
 
     @Override
@@ -326,7 +324,7 @@ public class PeripheralAPI implements ILuaAPI, IAPIEnvironment.IPeripheralChange
             "isPresent",
             "getType",
             "getMethods",
-            "call"
+            "call",
         };
     }
 
@@ -356,7 +354,6 @@ public class PeripheralAPI implements ILuaAPI, IAPIEnvironment.IPeripheralChange
                 ComputerSide side = ComputerSide.valueOfInsensitive( getString( args, 0 ) );
                 if( side != null )
                 {
-                    String type = null;
                     synchronized( m_peripherals )
                     {
                         PeripheralWrapper p = m_peripherals[side.ordinal()];

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

@@ -29,9 +29,7 @@ public class RedstoneAPI implements ILuaAPI
     @Override
     public String[] getNames()
     {
-        return new String[] {
-            "rs", "redstone"
-        };
+        return new String[] { "rs", "redstone" };
     }
 
     @Nonnull

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

@@ -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 )

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

@@ -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

@@ -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

@@ -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

@@ -37,8 +37,13 @@ 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;
+        }
     }
 
     /**

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

@@ -72,7 +72,8 @@ 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 );
     }
 
@@ -95,7 +96,8 @@ 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/computer/Computer.java

@@ -239,7 +239,6 @@ public class Computer
     }
 
     @Deprecated
-    @SuppressWarnings( "unused" )
     public void advance( double dt )
     {
         tick();

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

@@ -30,7 +30,10 @@ public enum ComputerSide
 
     private final String name;
 
-    ComputerSide( String name ) {this.name = name;}
+    ComputerSide( String name )
+    {
+        this.name = name;
+    }
 
     @Nonnull
     public static ComputerSide valueOf( int side )

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;
@@ -92,7 +93,7 @@ public class JarMount implements IMount
         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

@@ -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/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/Config.java

@@ -277,7 +277,7 @@ 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 );

src/main/java/dan200/computercraft/shared/common/BlockGeneric.java

@@ -51,7 +51,6 @@ public abstract class BlockGeneric extends Block implements ITileEntityProvider
 
     @Override
     @Deprecated
-    @SuppressWarnings( "deprecation" )
     public final void neighborChanged( IBlockState state, World world, BlockPos pos, Block neighbourBlock, BlockPos neighbourPos )
     {
         TileEntity tile = world.getTileEntity( pos );

src/main/java/dan200/computercraft/shared/common/TileGeneric.java

@@ -63,7 +63,6 @@ public abstract class TileGeneric extends TileEntity
     {
     }
 
-    @SuppressWarnings( "deprecation" )
     public void onNeighbourChange( @Nonnull BlockPos neighbour )
     {
         onNeighbourChange();

src/main/java/dan200/computercraft/shared/computer/apis/CommandAPI.java

@@ -47,9 +47,7 @@ public class CommandAPI implements ILuaAPI
     @Override
     public String[] getNames()
     {
-        return new String[] {
-            "commands"
-        };
+        return new String[] { "commands" };
     }
 
     @Nonnull
@@ -62,7 +60,7 @@ public class CommandAPI implements ILuaAPI
             "list",
             "getBlockPosition",
             "getBlockInfos",
-            "getBlockInfo"
+            "getBlockInfo",
         };
     }
 
@@ -85,7 +83,7 @@ public class CommandAPI implements ILuaAPI
         {
             sender.clearOutput();
             int result = commandManager.executeCommand( sender, command );
-            return new Object[] { result > 0, sender.copyOutput() };
+            return new Object[] { result > 0, sender.copyOutput(), result };
         }
         catch( Throwable t )
         {

src/main/java/dan200/computercraft/shared/computer/blocks/TileComputer.java

@@ -32,7 +32,7 @@ public class TileComputer extends TileComputerBase
         ServerComputer computer = new ServerComputer(
             getWorld(),
             id,
-            m_label,
+            label,
             instanceID,
             family,
             ComputerCraft.terminalWidth_computer,

src/main/java/dan200/computercraft/shared/computer/blocks/TileComputerBase.java

@@ -47,7 +47,7 @@ public abstract class TileComputerBase extends TileGeneric implements IComputerT
 {
     private int m_instanceID = -1;
     private int m_computerID = -1;
-    protected String m_label = null;
+    protected String label = null;
     private boolean m_on = false;
     boolean m_startOn = false;
     private boolean m_fresh = false;
@@ -190,7 +190,7 @@ public abstract class TileComputerBase extends TileGeneric implements IComputerT
 
                 m_fresh = false;
                 m_computerID = computer.getID();
-                m_label = computer.getLabel();
+                label = computer.getLabel();
                 m_on = computer.isOn();
 
                 if( computer.hasOutputChanged() ) updateOutput();
@@ -212,9 +212,9 @@ public abstract class TileComputerBase extends TileGeneric implements IComputerT
         {
             nbt.setInteger( "computerID", m_computerID );
         }
-        if( m_label != null )
+        if( label != null )
         {
-            nbt.setString( "label", m_label );
+            nbt.setString( "label", label );
         }
         nbt.setBoolean( "on", m_on );
         return super.writeToNBT( nbt );
@@ -248,7 +248,7 @@ public abstract class TileComputerBase extends TileGeneric implements IComputerT
         m_computerID = id;
 
         // Load label
-        m_label = nbt.hasKey( "label" ) ? nbt.getString( "label" ) : null;
+        label = nbt.hasKey( "label" ) ? nbt.getString( "label" ) : null;
 
         // Load power state
         m_startOn = nbt.getBoolean( "on" );
@@ -361,7 +361,7 @@ public abstract class TileComputerBase extends TileGeneric implements IComputerT
     @Override
     public final String getLabel()
     {
-        return m_label;
+        return label;
     }
 
     @Override
@@ -378,9 +378,9 @@ public abstract class TileComputerBase extends TileGeneric implements IComputerT
     @Override
     public final void setLabel( String label )
     {
-        if( getWorld().isRemote || Objects.equals( m_label, label ) ) return;
+        if( getWorld().isRemote || Objects.equals( this.label, label ) ) return;
 
-        m_label = label;
+        this.label = label;
         ServerComputer computer = getServerComputer();
         if( computer != null ) computer.setLabel( label );
         markDirty();
@@ -453,8 +453,8 @@ public abstract class TileComputerBase extends TileGeneric implements IComputerT
     protected void writeDescription( @Nonnull NBTTagCompound nbt )
     {
         super.writeDescription( nbt );
-        nbt.setInteger( "instanceID", createServerComputer().getInstanceID() );
-        if( m_label != null ) nbt.setString( "label", m_label );
+        if( m_instanceID >= 0 ) nbt.setInteger( "instanceID", m_instanceID );
+        if( label != null ) nbt.setString( "label", label );
         if( m_computerID >= 0 ) nbt.setInteger( "computerID", m_computerID );
     }
 
@@ -463,7 +463,7 @@ public abstract class TileComputerBase extends TileGeneric implements IComputerT
     {
         super.readDescription( nbt );
         m_instanceID = nbt.getInteger( "instanceID" );
-        m_label = nbt.hasKey( "label" ) ? nbt.getString( "label" ) : null;
+        label = nbt.hasKey( "label" ) ? nbt.getString( "label" ) : null;
         m_computerID = nbt.hasKey( "computerID" ) ? nbt.getInteger( "computerID" ) : -1;
     }
 
@@ -474,7 +474,7 @@ public abstract class TileComputerBase extends TileGeneric implements IComputerT
             unload();
             m_instanceID = copy.m_instanceID;
             m_computerID = copy.m_computerID;
-            m_label = copy.m_label;
+            label = copy.label;
             m_on = copy.m_on;
             m_startOn = copy.m_startOn;
             updateBlock();
@@ -493,13 +493,13 @@ public abstract class TileComputerBase extends TileGeneric implements IComputerT
     @Override
     public String getName()
     {
-        return hasCustomName() ? m_label : getBlockType().getTranslationKey();
+        return hasCustomName() ? label : getBlockType().getTranslationKey();
     }
 
     @Override
     public boolean hasCustomName()
     {
-        return !Strings.isNullOrEmpty( m_label );
+        return !Strings.isNullOrEmpty( label );
     }
 
     @Nonnull

src/main/java/dan200/computercraft/shared/computer/core/ComputerRegistry.java

@@ -11,9 +11,9 @@ import java.util.HashMap;
 import java.util.Map;
 import java.util.Random;
 
-public class ComputerRegistry<TComputer extends IComputer>
+public class ComputerRegistry<T extends IComputer>
 {
-    private Map<Integer, TComputer> m_computers;
+    private Map<Integer, T> m_computers;
     private int m_nextUnusedInstanceID;
     private int m_sessionID;
 
@@ -33,12 +33,12 @@ public class ComputerRegistry<TComputer extends IComputer>
         return m_nextUnusedInstanceID++;
     }
 
-    public Collection<TComputer> getComputers()
+    public Collection<T> getComputers()
     {
         return m_computers.values();
     }
 
-    public TComputer get( int instanceID )
+    public T get( int instanceID )
     {
         if( instanceID >= 0 )
         {
@@ -55,7 +55,7 @@ public class ComputerRegistry<TComputer extends IComputer>
         return m_computers.containsKey( instanceID );
     }
 
-    public void add( int instanceID, TComputer computer )
+    public void add( int instanceID, T computer )
     {
         if( m_computers.containsKey( instanceID ) )
         {

src/main/java/dan200/computercraft/shared/computer/core/ServerComputer.java

@@ -220,6 +220,13 @@ public class ServerComputer extends ServerTerminal implements IComputer, IComput
         return m_instanceID;
     }
 
+    /*
+     * getID and getLabel are deprecated on IComputer, as they do not make sense in ClientComputer.
+     * However, for compatibility reasons, we still need these here, and have no choice but to override the IComputer methods.
+     *
+     * Hence, we suppress the deprecation warning.
+     */
+
     @Override
     @SuppressWarnings( "deprecation" )
     public int getID()

src/main/java/dan200/computercraft/shared/integration/charset/BundledCapabilityProvider.java

@@ -1,9 +1,8 @@
 /*
  * This file is part of ComputerCraft - http://www.computercraft.info
- * Copyright Daniel Ratcliffe, 2011-2018. Do not distribute without permission.
+ * Copyright Daniel Ratcliffe, 2011-2019. Do not distribute without permission.
  * Send enquiries to dratcliffe@gmail.com
  */
-
 package dan200.computercraft.shared.integration.charset;
 
 import dan200.computercraft.shared.common.TileGeneric;

src/main/java/dan200/computercraft/shared/integration/charset/BundledRedstoneProvider.java

@@ -1,9 +1,8 @@
 /*
  * This file is part of ComputerCraft - http://www.computercraft.info
- * Copyright Daniel Ratcliffe, 2011-2018. Do not distribute without permission.
+ * Copyright Daniel Ratcliffe, 2011-2019. Do not distribute without permission.
  * Send enquiries to dratcliffe@gmail.com
  */
-
 package dan200.computercraft.shared.integration.charset;
 
 import dan200.computercraft.api.redstone.IBundledRedstoneProvider;

src/main/java/dan200/computercraft/shared/integration/charset/IntegrationCharset.java

@@ -1,9 +1,8 @@
 /*
  * This file is part of ComputerCraft - http://www.computercraft.info
- * Copyright Daniel Ratcliffe, 2011-2018. Do not distribute without permission.
+ * Copyright Daniel Ratcliffe, 2011-2019. Do not distribute without permission.
  * Send enquiries to dratcliffe@gmail.com
  */
-
 package dan200.computercraft.shared.integration.charset;
 
 import dan200.computercraft.ComputerCraft;

src/main/java/dan200/computercraft/shared/integration/jei/JEIComputerCraft.java

@@ -90,6 +90,7 @@ public class JEIComputerCraft implements IModPlugin
         ingredients.addIngredientsAtRuntime( VanillaTypes.ITEM, upgradeItems );
 
         // Hide all upgrade recipes
+        @SuppressWarnings( "unchecked" )
         IRecipeCategory<? extends IRecipeWrapper> category = (IRecipeCategory<? extends IRecipeWrapper>) registry.getRecipeCategory( VanillaRecipeCategoryUid.CRAFTING );
         if( category != null )
         {

src/main/java/dan200/computercraft/shared/media/inventory/ContainerHeldItem.java

@@ -6,7 +6,6 @@
 
 package dan200.computercraft.shared.media.inventory;
 
-import dan200.computercraft.shared.util.InventoryUtil;
 import net.minecraft.entity.player.EntityPlayer;
 import net.minecraft.inventory.Container;
 import net.minecraft.item.ItemStack;
@@ -22,7 +21,7 @@ public class ContainerHeldItem extends Container
     public ContainerHeldItem( EntityPlayer player, EnumHand hand )
     {
         m_hand = hand;
-        m_stack = InventoryUtil.copyItem( player.getHeldItem( hand ) );
+        m_stack = player.getHeldItem( hand ).copy();
     }
 
     @Nonnull

src/main/java/dan200/computercraft/shared/peripheral/PeripheralType.java

@@ -39,5 +39,8 @@ public enum PeripheralType implements IStringSerializable
     }
 
     @Override
-    public String toString() { return name; }
+    public String toString()
+    {
+        return name;
+    }
 }

src/main/java/dan200/computercraft/shared/peripheral/commandblock/CommandBlockPeripheral.java

@@ -52,7 +52,7 @@ public class CommandBlockPeripheral implements IPeripheral
         {
             case 0: // getCommand
                 return context.executeMainThreadTask( () -> new Object[] {
-                    m_commandBlock.getCommandBlockLogic().getCommand()
+                    m_commandBlock.getCommandBlockLogic().getCommand(),
                 } );
             case 1:
             {

src/main/java/dan200/computercraft/shared/peripheral/diskdrive/DiskDrivePeripheral.java

@@ -11,6 +11,7 @@ import dan200.computercraft.api.lua.LuaException;
 import dan200.computercraft.api.media.IMedia;
 import dan200.computercraft.api.peripheral.IComputerAccess;
 import dan200.computercraft.api.peripheral.IPeripheral;
+import dan200.computercraft.shared.MediaProviders;
 import dan200.computercraft.shared.media.items.ItemDiskLegacy;
 import dan200.computercraft.shared.util.StringUtil;
 import net.minecraft.item.Item;
@@ -20,11 +21,11 @@ import javax.annotation.Nonnull;
 
 import static dan200.computercraft.core.apis.ArgumentHelper.optString;
 
-public class DiskDrivePeripheral implements IPeripheral
+class DiskDrivePeripheral implements IPeripheral
 {
     private final TileDiskDrive m_diskDrive;
 
-    public DiskDrivePeripheral( TileDiskDrive diskDrive )
+    DiskDrivePeripheral( TileDiskDrive diskDrive )
     {
         m_diskDrive = diskDrive;
     }
@@ -51,12 +52,12 @@ public class DiskDrivePeripheral implements IPeripheral
             "playAudio",
             "stopAudio",
             "ejectDisk",
-            "getDiskID"
+            "getDiskID",
         };
     }
 
     @Override
-    public Object[] callMethod( @Nonnull IComputerAccess computer, @Nonnull ILuaContext context, int method, @Nonnull Object[] arguments ) throws LuaException
+    public Object[] callMethod( @Nonnull IComputerAccess computer, @Nonnull ILuaContext context, int method, @Nonnull Object[] arguments ) throws LuaException, InterruptedException
     {
         switch( method )
         {
@@ -64,21 +65,26 @@ public class DiskDrivePeripheral implements IPeripheral
                 return new Object[] { !m_diskDrive.getDiskStack().isEmpty() };
             case 1: // getDiskLabel
             {
-                IMedia media = m_diskDrive.getDiskMedia();
-                return media == null ? null : new Object[] { media.getLabel( m_diskDrive.getDiskStack() ) };
+                ItemStack stack = m_diskDrive.getDiskStack();
+                IMedia media = MediaProviders.get( stack );
+                return media == null ? null : new Object[] { media.getLabel( stack ) };
             }
             case 2: // setDiskLabel
             {
                 String label = optString( arguments, 0, null );
 
-                IMedia media = m_diskDrive.getDiskMedia();
-                if( media == null ) return null;
+                return context.executeMainThreadTask( () -> {
+                    ItemStack stack = m_diskDrive.getDiskStack();
+                    IMedia media = MediaProviders.get( stack );
+                    if( media == null ) return null;
 
-                ItemStack disk = m_diskDrive.getDiskStack();
-                label = StringUtil.normaliseLabel( label );
-                if( !media.setLabel( disk, label ) ) throw new LuaException( "Disk label cannot be changed" );
-                m_diskDrive.setDiskStack( disk );
-                return null;
+                    if( !media.setLabel( stack, StringUtil.normaliseLabel( label ) ) )
+                    {
+                        throw new LuaException( "Disk label cannot be changed" );
+                    }
+                    m_diskDrive.setDiskStack( stack );
+                    return null;
+                } );
             }
             case 3: // hasData
                 return new Object[] { m_diskDrive.getDiskMountPath( computer ) != null };
@@ -87,14 +93,16 @@ public class DiskDrivePeripheral implements IPeripheral
             case 5:
             {
                 // hasAudio
-                IMedia media = m_diskDrive.getDiskMedia();
-                return new Object[] { media != null && media.getAudio( m_diskDrive.getDiskStack() ) != null };
+                ItemStack stack = m_diskDrive.getDiskStack();
+                IMedia media = MediaProviders.get( stack );
+                return new Object[] { media != null && media.getAudio( stack ) != null };
             }
             case 6:
             {
                 // getAudioTitle
-                IMedia media = m_diskDrive.getDiskMedia();
-                return new Object[] { media != null ? media.getAudioTitle( m_diskDrive.getDiskStack() ) : false };
+                ItemStack stack = m_diskDrive.getDiskStack();
+                IMedia media = MediaProviders.get( stack );
+                return new Object[] { media != null ? media.getAudioTitle( stack ) : false };
             }
             case 7: // playAudio
                 m_diskDrive.playDiskAudio();
@@ -131,8 +139,7 @@ public class DiskDrivePeripheral implements IPeripheral
     @Override
     public boolean equals( IPeripheral other )
     {
-        if( this == other ) return true;
-        return other instanceof DiskDrivePeripheral && ((DiskDrivePeripheral) other).m_diskDrive == m_diskDrive;
+        return this == other || other instanceof DiskDrivePeripheral && ((DiskDrivePeripheral) other).m_diskDrive == m_diskDrive;
     }
 
     @Nonnull

src/main/java/dan200/computercraft/shared/peripheral/diskdrive/TileDiskDrive.java

@@ -318,35 +318,31 @@ public class TileDiskDrive extends TilePeripheralBase implements DefaultInventor
     }
 
     @Nonnull
-    public ItemStack getDiskStack()
+    ItemStack getDiskStack()
     {
         return getStackInSlot( 0 );
     }
 
-    public void setDiskStack( @Nonnull ItemStack stack )
+    void setDiskStack( @Nonnull ItemStack stack )
     {
         setInventorySlotContents( 0, stack );
     }
 
-    public IMedia getDiskMedia()
+    private IMedia getDiskMedia()
     {
         return MediaProviders.get( getDiskStack() );
     }
 
-    public String getDiskMountPath( IComputerAccess computer )
+    String getDiskMountPath( IComputerAccess computer )
     {
         synchronized( this )
         {
-            if( m_computers.containsKey( computer ) )
-            {
-                MountInfo info = m_computers.get( computer );
-                return info.mountPath;
-            }
+            MountInfo info = m_computers.get( computer );
+            return info != null ? info.mountPath : null;
         }
-        return null;
     }
 
-    public void mount( IComputerAccess computer )
+    void mount( IComputerAccess computer )
     {
         synchronized( this )
         {
@@ -355,7 +351,7 @@ public class TileDiskDrive extends TilePeripheralBase implements DefaultInventor
         }
     }
 
-    public void unmount( IComputerAccess computer )
+    void unmount( IComputerAccess computer )
     {
         synchronized( this )
         {
@@ -364,7 +360,7 @@ public class TileDiskDrive extends TilePeripheralBase implements DefaultInventor
         }
     }
 
-    public void playDiskAudio()
+    void playDiskAudio()
     {
         synchronized( this )
         {
@@ -377,7 +373,7 @@ public class TileDiskDrive extends TilePeripheralBase implements DefaultInventor
         }
     }
 
-    public void stopDiskAudio()
+    void stopDiskAudio()
     {
         synchronized( this )
         {
@@ -386,7 +382,7 @@ public class TileDiskDrive extends TilePeripheralBase implements DefaultInventor
         }
     }
 
-    public void ejectDisk()
+    void ejectDisk()
     {
         synchronized( this )
         {

src/main/java/dan200/computercraft/shared/peripheral/modem/ModemPeripheral.java

@@ -87,7 +87,7 @@ public abstract class ModemPeripheral implements IPeripheral, IPacketSender, IPa
             for( IComputerAccess computer : m_computers )
             {
                 computer.queueEvent( "modem_message", new Object[] {
-                    computer.getAttachmentName(), packet.getChannel(), packet.getReplyChannel(), packet.getPayload(), distance
+                    computer.getAttachmentName(), packet.getChannel(), packet.getReplyChannel(), packet.getPayload(), distance,
                 } );
             }
         }
@@ -103,7 +103,7 @@ public abstract class ModemPeripheral implements IPeripheral, IPacketSender, IPa
             for( IComputerAccess computer : m_computers )
             {
                 computer.queueEvent( "modem_message", new Object[] {
-                    computer.getAttachmentName(), packet.getChannel(), packet.getReplyChannel(), packet.getPayload()
+                    computer.getAttachmentName(), packet.getChannel(), packet.getReplyChannel(), packet.getPayload(),
                 } );
             }
         }

src/main/java/dan200/computercraft/shared/peripheral/modem/wired/WiredModemPeripheral.java

@@ -277,7 +277,7 @@ public abstract class WiredModemPeripheral extends ModemPeripheral implements IW
         private final String[] m_methods;
         private final Map<String, Integer> m_methodMap;
 
-        public RemotePeripheralWrapper( WiredModemElement element, IPeripheral peripheral, IComputerAccess computer, String name )
+        RemotePeripheralWrapper( WiredModemElement element, IPeripheral peripheral, IComputerAccess computer, String name )
         {
             m_element = element;
             m_peripheral = peripheral;

src/main/java/dan200/computercraft/shared/peripheral/monitor/TileMonitor.java

@@ -142,7 +142,7 @@ public class TileMonitor extends TileGeneric implements ITilePeripheral, IPeriph
                     for( IComputerAccess computer : monitor.m_computers )
                     {
                         computer.queueEvent( "monitor_resize", new Object[] {
-                            computer.getAttachmentName()
+                            computer.getAttachmentName(),
                         } );
                     }
                 }
@@ -660,7 +660,7 @@ public class TileMonitor extends TileGeneric implements ITilePeripheral, IPeriph
                 for( IComputerAccess computer : monitor.m_computers )
                 {
                     computer.queueEvent( "monitor_touch", new Object[] {
-                        computer.getAttachmentName(), xCharPos, yCharPos
+                        computer.getAttachmentName(), xCharPos, yCharPos,
                     } );
                 }
             }

src/main/java/dan200/computercraft/shared/peripheral/printer/PrinterPeripheral.java

@@ -11,6 +11,7 @@ import dan200.computercraft.api.lua.LuaException;
 import dan200.computercraft.api.peripheral.IComputerAccess;
 import dan200.computercraft.api.peripheral.IPeripheral;
 import dan200.computercraft.core.terminal.Terminal;
+import dan200.computercraft.shared.util.StringUtil;
 
 import javax.annotation.Nonnull;
 
@@ -51,8 +52,13 @@ public class PrinterPeripheral implements IPeripheral
     }
 
     @Override
-    public Object[] callMethod( @Nonnull IComputerAccess computer, @Nonnull ILuaContext context, int method, @Nonnull Object[] args ) throws LuaException
+    public Object[] callMethod( @Nonnull IComputerAccess computer, @Nonnull ILuaContext context, int method, @Nonnull Object[] args ) throws LuaException, InterruptedException
     {
+        // FIXME: There's a theoretical race condition here between getCurrentPage and then using the page. Ideally
+        //  we'd lock on the page, consume it, and unlock.
+
+        // FIXME: None of our page modification functions actually mark the tile as dirty, so the page may not be
+        //  persisted correctly.
         switch( method )
         {
             case 0: // write
@@ -89,10 +95,13 @@ public class PrinterPeripheral implements IPeripheral
                 return new Object[] { width, height };
             }
             case 4: // newPage
-                return new Object[] { m_printer.startNewPage() };
+                return context.executeMainThreadTask( () -> new Object[] { m_printer.startNewPage() } );
             case 5: // endPage
                 getCurrentPage();
-                return new Object[] { m_printer.endCurrentPage() };
+                return context.executeMainThreadTask( () -> {
+                    getCurrentPage();
+                    return new Object[] { m_printer.endCurrentPage() };
+                } );
             case 6: // getInkLevel
                 return new Object[] { m_printer.getInkLevel() };
             case 7:
@@ -100,7 +109,7 @@ public class PrinterPeripheral implements IPeripheral
                 // setPageTitle
                 String title = optString( args, 0, "" );
                 getCurrentPage();
-                m_printer.setPageTitle( title );
+                m_printer.setPageTitle( StringUtil.normaliseLabel( title ) );
                 return null;
             }
             case 8: // getPaperLevel
@@ -123,13 +132,11 @@ public class PrinterPeripheral implements IPeripheral
         return m_printer;
     }
 
+    @Nonnull
     private Terminal getCurrentPage() throws LuaException
     {
         Terminal currentPage = m_printer.getCurrentPage();
-        if( currentPage == null )
-        {
-            throw new LuaException( "Page not started" );
-        }
+        if( currentPage == null ) throw new LuaException( "Page not started" );
         return currentPage;
     }
 }

src/main/java/dan200/computercraft/shared/peripheral/printer/TilePrinter.java

@@ -45,9 +45,9 @@ public class TilePrinter extends TilePeripheralBase implements DefaultSidedInven
 {
     // Statics
 
-    private static final int[] bottomSlots = new int[] { 7, 8, 9, 10, 11, 12 };
-    private static final int[] topSlots = new int[] { 1, 2, 3, 4, 5, 6 };
-    private static final int[] sideSlots = new int[] { 0 };
+    private static final int[] BOTTOM_SLOTS = new int[] { 7, 8, 9, 10, 11, 12 };
+    private static final int[] TOP_SLOTS = new int[] { 1, 2, 3, 4, 5, 6 };
+    private static final int[] SIDE_SLOTS = new int[] { 0 };
 
     // Members
 
@@ -88,18 +88,12 @@ public class TilePrinter extends TilePeripheralBase implements DefaultSidedInven
         }
 
         // Read inventory
-        synchronized( m_inventory )
+        NBTTagList itemList = nbt.getTagList( "Items", Constants.NBT.TAG_COMPOUND );
+        for( int i = 0; i < itemList.tagCount(); i++ )
         {
-            NBTTagList nbttaglist = nbt.getTagList( "Items", Constants.NBT.TAG_COMPOUND );
-            for( int i = 0; i < nbttaglist.tagCount(); i++ )
-            {
-                NBTTagCompound itemTag = nbttaglist.getCompoundTagAt( i );
-                int j = itemTag.getByte( "Slot" ) & 0xff;
-                if( j < m_inventory.size() )
-                {
-                    m_inventory.set( j, new ItemStack( itemTag ) );
-                }
-            }
+            NBTTagCompound itemTag = itemList.getCompoundTagAt( i );
+            int slot = itemTag.getByte( "Slot" ) & 0xff;
+            if( slot < m_inventory.size() ) m_inventory.set( slot, new ItemStack( itemTag ) );
         }
     }
 
@@ -116,21 +110,18 @@ public class TilePrinter extends TilePeripheralBase implements DefaultSidedInven
         }
 
         // Write inventory
-        synchronized( m_inventory )
+        NBTTagList itemList = new NBTTagList();
+        for( int i = 0; i < m_inventory.size(); i++ )
         {
-            NBTTagList nbttaglist = new NBTTagList();
-            for( int i = 0; i < m_inventory.size(); i++ )
-            {
-                if( !m_inventory.get( i ).isEmpty() )
-                {
-                    NBTTagCompound tag = new NBTTagCompound();
-                    tag.setByte( "Slot", (byte) i );
-                    m_inventory.get( i ).writeToNBT( tag );
-                    nbttaglist.appendTag( tag );
-                }
-            }
-            nbt.setTag( "Items", nbttaglist );
+            ItemStack stack = m_inventory.get( i );
+            if( stack.isEmpty() ) continue;
+
+            NBTTagCompound tag = new NBTTagCompound();
+            tag.setByte( "Slot", (byte) i );
+            stack.writeToNBT( tag );
+            itemList.appendTag( tag );
         }
+        nbt.setTag( "Items", itemList );
 
         return super.writeToNBT( nbt );
     }
@@ -148,7 +139,7 @@ public class TilePrinter extends TilePeripheralBase implements DefaultSidedInven
         return super.shouldRefresh( world, pos, oldState, newState ) || BlockPeripheral.getPeripheralType( newState ) != PeripheralType.Printer;
     }
 
-    public boolean isPrinting()
+    boolean isPrinting()
     {
         return m_printing;
     }
@@ -173,73 +164,59 @@ public class TilePrinter extends TilePeripheralBase implements DefaultSidedInven
 
     @Nonnull
     @Override
-    public ItemStack getStackInSlot( int i )
+    public ItemStack getStackInSlot( int slot )
     {
-        return m_inventory.get( i );
+        return m_inventory.get( slot );
     }
 
     @Nonnull
     @Override
-    public ItemStack removeStackFromSlot( int i )
+    public ItemStack removeStackFromSlot( int slot )
     {
-        synchronized( m_inventory )
-        {
-            ItemStack result = m_inventory.get( i );
-            m_inventory.set( i, ItemStack.EMPTY );
-            markDirty();
-            updateAnim();
-            return result;
-        }
+        ItemStack result = m_inventory.get( slot );
+        m_inventory.set( slot, ItemStack.EMPTY );
+        markDirty();
+        updateAnim();
+        return result;
     }
 
     @Nonnull
     @Override
-    public ItemStack decrStackSize( int i, int j )
+    public ItemStack decrStackSize( int slot, int count )
     {
-        synchronized( m_inventory )
+        ItemStack stack = m_inventory.get( slot );
+        if( stack.isEmpty() ) return ItemStack.EMPTY;
+
+        if( stack.getCount() <= count )
         {
-            if( m_inventory.get( i ).isEmpty() ) return ItemStack.EMPTY;
-
-            if( m_inventory.get( i ).getCount() <= j )
-            {
-                ItemStack itemstack = m_inventory.get( i );
-                m_inventory.set( i, ItemStack.EMPTY );
-                markDirty();
-                updateAnim();
-                return itemstack;
-            }
-
-            ItemStack part = m_inventory.get( i ).splitStack( j );
-            if( m_inventory.get( i ).isEmpty() )
-            {
-                m_inventory.set( i, ItemStack.EMPTY );
-                updateAnim();
-            }
-            markDirty();
-            return part;
+            setInventorySlotContents( slot, ItemStack.EMPTY );
+            return stack;
         }
+
+        ItemStack part = stack.splitStack( count );
+        if( m_inventory.get( slot ).isEmpty() )
+        {
+            m_inventory.set( slot, ItemStack.EMPTY );
+            updateAnim();
+        }
+        markDirty();
+        return part;
     }
 
     @Override
-    public void setInventorySlotContents( int i, @Nonnull ItemStack stack )
+    public void setInventorySlotContents( int slot, @Nonnull ItemStack stack )
     {
-        synchronized( m_inventory )
-        {
-            m_inventory.set( i, stack );
-            markDirty();
-            updateAnim();
-        }
+        m_inventory.set( slot, stack );
+        markDirty();
+        updateAnim();
     }
 
     @Override
     public void clear()
     {
-        synchronized( m_inventory )
-        {
-            for( int i = 0; i < m_inventory.size(); i++ ) m_inventory.set( i, ItemStack.EMPTY );
-            markDirty();
-            updateAnim();
-        }
+        for( int i = 0; i < m_inventory.size(); i++ ) m_inventory.set( i, ItemStack.EMPTY );
+        markDirty();
+        updateAnim();
     }
 
     @Override
@@ -249,7 +226,7 @@ public class TilePrinter extends TilePeripheralBase implements DefaultSidedInven
         {
             return isInk( stack );
         }
-        else if( slot >= topSlots[0] && slot <= topSlots[topSlots.length - 1] )
+        else if( slot >= TOP_SLOTS[0] && slot <= TOP_SLOTS[TOP_SLOTS.length - 1] )
         {
             return isPaper( stack );
         }
@@ -295,11 +272,11 @@ public class TilePrinter extends TilePeripheralBase implements DefaultSidedInven
         switch( side )
         {
             case DOWN: // Bottom (Out tray)
-                return bottomSlots;
+                return BOTTOM_SLOTS;
             case UP: // Top (In tray)
-                return topSlots;
+                return TOP_SLOTS;
             default: // Sides (Ink)
-                return sideSlots;
+                return SIDE_SLOTS;
         }
     }
 
@@ -311,14 +288,18 @@ public class TilePrinter extends TilePeripheralBase implements DefaultSidedInven
         return new PrinterPeripheral( this );
     }
 
-    public Terminal getCurrentPage()
+    @Nullable
+    Terminal getCurrentPage()
     {
-        return m_printing ? m_page : null;
+        synchronized( m_page )
+        {
+            return m_printing ? m_page : null;
+        }
     }
 
-    public boolean startNewPage()
+    boolean startNewPage()
     {
-        synchronized( m_inventory )
+        synchronized( m_page )
         {
             if( !canInputPage() ) return false;
             if( m_printing && !outputPage() ) return false;
@@ -326,49 +307,36 @@ public class TilePrinter extends TilePeripheralBase implements DefaultSidedInven
         }
     }
 
-    public boolean endCurrentPage()
+    boolean endCurrentPage()
     {
-        synchronized( m_inventory )
+        synchronized( m_page )
         {
-            if( m_printing && outputPage() )
-            {
-                return true;
-            }
-        }
-        return false;
-    }
-
-    public int getInkLevel()
-    {
-        synchronized( m_inventory )
-        {
-            ItemStack inkStack = m_inventory.get( 0 );
-            return isInk( inkStack ) ? inkStack.getCount() : 0;
+            return m_printing && outputPage();
         }
     }
 
-    public int getPaperLevel()
+    int getInkLevel()
+    {
+        ItemStack inkStack = m_inventory.get( 0 );
+        return isInk( inkStack ) ? inkStack.getCount() : 0;
+    }
+
+    int getPaperLevel()
     {
         int count = 0;
-        synchronized( m_inventory )
+        for( int i = 1; i < 7; i++ )
         {
-            for( int i = 1; i < 7; i++ )
-            {
-                ItemStack paperStack = m_inventory.get( i );
-                if( !paperStack.isEmpty() && isPaper( paperStack ) )
-                {
-                    count += paperStack.getCount();
-                }
-            }
+            ItemStack paperStack = m_inventory.get( i );
+            if( isPaper( paperStack ) ) count += paperStack.getCount();
         }
         return count;
     }
 
-    public void setPageTitle( String title )
+    void setPageTitle( String title )
     {
-        if( m_printing )
+        synchronized( m_page )
         {
-            m_pageTitle = title;
+            if( m_printing ) m_pageTitle = title;
         }
     }
 
@@ -385,145 +353,126 @@ public class TilePrinter extends TilePeripheralBase implements DefaultSidedInven
 
     private boolean canInputPage()
     {
-        synchronized( m_inventory )
-        {
-            ItemStack inkStack = m_inventory.get( 0 );
-            return !inkStack.isEmpty() && isInk( inkStack ) && getPaperLevel() > 0;
-        }
+        ItemStack inkStack = m_inventory.get( 0 );
+        return !inkStack.isEmpty() && isInk( inkStack ) && getPaperLevel() > 0;
     }
 
     private boolean inputPage()
     {
-        synchronized( m_inventory )
+        ItemStack inkStack = m_inventory.get( 0 );
+        if( !isInk( inkStack ) ) return false;
+
+        for( int i = 1; i < 7; i++ )
         {
-            ItemStack inkStack = m_inventory.get( 0 );
-            if( !isInk( inkStack ) ) return false;
+            ItemStack paperStack = m_inventory.get( i );
+            if( paperStack.isEmpty() || !isPaper( paperStack ) ) continue;
 
-            for( int i = 1; i < 7; i++ )
+            // Setup the new page
+            int colour = inkStack.getItemDamage();
+            m_page.setTextColour( colour >= 0 && colour < 16 ? 15 - colour : 15 );
+
+            m_page.clear();
+            if( paperStack.getItem() instanceof ItemPrintout )
             {
-                ItemStack paperStack = m_inventory.get( i );
-                if( !paperStack.isEmpty() && isPaper( paperStack ) )
+                m_pageTitle = ItemPrintout.getTitle( paperStack );
+                String[] text = ItemPrintout.getText( paperStack );
+                String[] textColour = ItemPrintout.getColours( paperStack );
+                for( int y = 0; y < m_page.getHeight(); y++ )
                 {
-                    // Setup the new page
-                    int colour = inkStack.getItemDamage();
-                    m_page.setTextColour( colour >= 0 && colour < 16 ? 15 - colour : 15 );
-
-                    m_page.clear();
-                    if( paperStack.getItem() instanceof ItemPrintout )
-                    {
-                        m_pageTitle = ItemPrintout.getTitle( paperStack );
-                        String[] text = ItemPrintout.getText( paperStack );
-                        String[] textColour = ItemPrintout.getColours( paperStack );
-                        for( int y = 0; y < m_page.getHeight(); y++ )
-                        {
-                            m_page.setLine( y, text[y], textColour[y], "" );
-                        }
-                    }
-                    else
-                    {
-                        m_pageTitle = "";
-                    }
-                    m_page.setCursorPos( 0, 0 );
-
-                    // Decrement ink
-                    inkStack.shrink( 1 );
-                    if( inkStack.isEmpty() ) m_inventory.set( 0, ItemStack.EMPTY );
-
-                    // Decrement paper
-                    paperStack.shrink( 1 );
-                    if( paperStack.isEmpty() )
-                    {
-                        m_inventory.set( i, ItemStack.EMPTY );
-                        updateAnim();
-                    }
-
-                    markDirty();
-                    m_printing = true;
-                    return true;
+                    m_page.setLine( y, text[y], textColour[y], "" );
                 }
             }
-            return false;
+            else
+            {
+                m_pageTitle = "";
+            }
+            m_page.setCursorPos( 0, 0 );
+
+            // Decrement ink
+            inkStack.shrink( 1 );
+            if( inkStack.isEmpty() ) m_inventory.set( 0, ItemStack.EMPTY );
+
+            // Decrement paper
+            paperStack.shrink( 1 );
+            if( paperStack.isEmpty() )
+            {
+                m_inventory.set( i, ItemStack.EMPTY );
+                updateAnim();
+            }
+
+            markDirty();
+            m_printing = true;
+            return true;
         }
+        return false;
     }
 
     private boolean outputPage()
     {
-        synchronized( m_page )
+        int height = m_page.getHeight();
+        String[] lines = new String[height];
+        String[] colours = new String[height];
+        for( int i = 0; i < height; i++ )
         {
-            int height = m_page.getHeight();
-            String[] lines = new String[height];
-            String[] colours = new String[height];
-            for( int i = 0; i < height; i++ )
-            {
-                lines[i] = m_page.getLine( i ).toString();
-                colours[i] = m_page.getTextColourLine( i ).toString();
-            }
-
-            ItemStack stack = ItemPrintout.createSingleFromTitleAndText( m_pageTitle, lines, colours );
-            synchronized( m_inventory )
-            {
-                for( int slot : bottomSlots )
-                {
-                    if( m_inventory.get( slot ).isEmpty() )
-                    {
-                        setInventorySlotContents( slot, stack );
-                        m_printing = false;
-                        return true;
-                    }
-                }
-            }
-            return false;
+            lines[i] = m_page.getLine( i ).toString();
+            colours[i] = m_page.getTextColourLine( i ).toString();
         }
+
+        ItemStack stack = ItemPrintout.createSingleFromTitleAndText( m_pageTitle, lines, colours );
+        for( int slot : BOTTOM_SLOTS )
+        {
+            if( m_inventory.get( slot ).isEmpty() )
+            {
+                setInventorySlotContents( slot, stack );
+                m_printing = false;
+                return true;
+            }
+        }
+        return false;
     }
 
     private void ejectContents()
     {
-        synchronized( m_inventory )
+        for( int i = 0; i < 13; i++ )
         {
-            for( int i = 0; i < 13; i++ )
+            ItemStack stack = m_inventory.get( i );
+            if( !stack.isEmpty() )
             {
-                ItemStack stack = m_inventory.get( i );
-                if( !stack.isEmpty() )
-                {
-                    // Remove the stack from the inventory
-                    setInventorySlotContents( i, ItemStack.EMPTY );
+                // Remove the stack from the inventory
+                setInventorySlotContents( i, ItemStack.EMPTY );
 
-                    // Spawn the item in the world
-                    BlockPos pos = getPos();
-                    double x = pos.getX() + 0.5;
-                    double y = pos.getY() + 0.75;
-                    double z = pos.getZ() + 0.5;
-                    WorldUtil.dropItemStack( stack, getWorld(), x, y, z );
-                }
+                // Spawn the item in the world
+                BlockPos pos = getPos();
+                double x = pos.getX() + 0.5;
+                double y = pos.getY() + 0.75;
+                double z = pos.getZ() + 0.5;
+                WorldUtil.dropItemStack( stack, getWorld(), x, y, z );
             }
         }
     }
 
     private void updateAnim()
     {
-        synchronized( m_inventory )
+        int anim = 0;
+        for( int i = 1; i < 7; i++ )
         {
-            int anim = 0;
-            for( int i = 1; i < 7; i++ )
+            ItemStack stack = m_inventory.get( i );
+            if( !stack.isEmpty() && isPaper( stack ) )
             {
-                ItemStack stack = m_inventory.get( i );
-                if( !stack.isEmpty() && isPaper( stack ) )
-                {
-                    anim += 1;
-                    break;
-                }
+                anim += 1;
+                break;
             }
-            for( int i = 7; i < 13; i++ )
-            {
-                ItemStack stack = m_inventory.get( i );
-                if( !stack.isEmpty() && isPaper( stack ) )
-                {
-                    anim += 2;
-                    break;
-                }
-            }
-            setAnim( anim );
         }
+        for( int i = 7; i < 13; i++ )
+        {
+            ItemStack stack = m_inventory.get( i );
+            if( !stack.isEmpty() && isPaper( stack ) )
+            {
+                anim += 2;
+                break;
+            }
+        }
+        setAnim( anim );
     }
 
     @Override

src/main/java/dan200/computercraft/shared/peripheral/speaker/SpeakerPeripheral.java

@@ -44,7 +44,7 @@ public abstract class SpeakerPeripheral implements IPeripheral
     {
         // FIXME: Should be abstract, but we need this for Plethora compat. We'll
         //  be able to change this in a few versions as we implement both there.
-        @SuppressWarnings( "deprecation" ) BlockPos pos = getPos();
+        BlockPos pos = getPos();
         return new Vec3d( pos.getX() + 0.5, pos.getY() + 0.5, pos.getZ() + 0.5 );
     }
 
@@ -71,8 +71,8 @@ public abstract class SpeakerPeripheral implements IPeripheral
     public String[] getMethodNames()
     {
         return new String[] {
-            "playSound", // Plays sound at resourceLocator
-            "playNote" // Plays note
+            "playSound",
+            "playNote",
         };
     }
 

src/main/java/dan200/computercraft/shared/pocket/apis/PocketAPI.java

@@ -35,9 +35,7 @@ public class PocketAPI implements ILuaAPI
     @Override
     public String[] getNames()
     {
-        return new String[] {
-            "pocket"
-        };
+        return new String[] { "pocket" };
     }
 
     @Nonnull
@@ -46,7 +44,7 @@ public class PocketAPI implements ILuaAPI
     {
         return new String[] {
             "equipBack",
-            "unequipBack"
+            "unequipBack",
         };
     }
 

src/main/java/dan200/computercraft/shared/turtle/FurnaceRefuelHandler.java

@@ -30,9 +30,13 @@ public final class FurnaceRefuelHandler implements TurtleRefuelEvent.Handler
     @Override
     public int refuel( @Nonnull ITurtleAccess turtle, @Nonnull ItemStack currentStack, int slot, int limit )
     {
-        ItemStack stack = turtle.getItemHandler().extractItem( slot, limit, false );
-        int fuelToGive = getFuelPerItem( stack ) * stack.getCount();
+        int fuelSpaceLeft = turtle.getFuelLimit() - turtle.getFuelLevel();
+        int fuelPerItem = getFuelPerItem( turtle.getItemHandler().getStackInSlot( slot ) );
+        int fuelItemLimit = (int) Math.ceil( fuelSpaceLeft / (double) fuelPerItem );
+        if( limit > fuelItemLimit ) limit = fuelItemLimit;
 
+        ItemStack stack = turtle.getItemHandler().extractItem( slot, limit, false );
+        int fuelToGive = fuelPerItem * stack.getCount();
         // Store the replacement item in the inventory
         ItemStack replacementStack = stack.getItem().getContainerItem( stack );
         if( !replacementStack.isEmpty() )

src/main/java/dan200/computercraft/shared/turtle/apis/TurtleAPI.java

@@ -45,9 +45,7 @@ public class TurtleAPI implements ILuaAPI
     @Override
     public String[] getNames()
     {
-        return new String[] {
-            "turtle"
-        };
+        return new String[] { "turtle" };
     }
 
     @Nonnull
@@ -336,9 +334,11 @@ public class TurtleAPI implements ILuaAPI
                 return tryCommand( context, new TurtleInspectCommand( InteractDirection.Up ) );
             case 40: // inspectDown
                 return tryCommand( context, new TurtleInspectCommand( InteractDirection.Down ) );
-            case 41:
+            case 41: // getItemDetail
             {
-                // getItemDetail
+                // FIXME: There's a race condition here if the stack is being modified (mutating NBT, etc...)
+                //  on another thread. The obvious solution is to move this into a command, but some programs rely
+                //  on this having a 0-tick delay.
                 int slot = parseOptionalSlotNumber( args, 0, m_turtle.getSelectedSlot() );
                 ItemStack stack = m_turtle.getInventory().getStackInSlot( slot );
                 if( stack.isEmpty() ) return new Object[] { null };

src/main/java/dan200/computercraft/shared/turtle/blocks/BlockTurtle.java

@@ -218,7 +218,7 @@ public class BlockTurtle extends BlockComputerBase
     @Deprecated
     public float getExplosionResistance( Entity exploder )
     {
-        if( getFamily() == ComputerFamily.Advanced && (exploder instanceof EntityLivingBase || exploder instanceof EntityFireball) )
+        if( getFamily() == ComputerFamily.Advanced || exploder instanceof EntityLivingBase || exploder instanceof EntityFireball )
         {
             return 2000;
         }

src/main/java/dan200/computercraft/shared/turtle/blocks/TileTurtle.java

@@ -43,19 +43,16 @@ import net.minecraftforge.items.wrapper.InvWrapper;
 
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
+import java.util.Collections;
 
 import static net.minecraftforge.items.CapabilityItemHandler.ITEM_HANDLER_CAPABILITY;
 
 public class TileTurtle extends TileComputerBase implements ITurtleTile, DefaultInventory
 {
-    // Statics
-
     public static final int INVENTORY_SIZE = 16;
     public static final int INVENTORY_WIDTH = 4;
     public static final int INVENTORY_HEIGHT = 4;
 
-    // Members
-
     enum MoveState
     {
         NOT_MOVED,
@@ -63,12 +60,12 @@ public class TileTurtle extends TileComputerBase implements ITurtleTile, Default
         MOVED
     }
 
-    private NonNullList<ItemStack> m_inventory;
-    private NonNullList<ItemStack> m_previousInventory;
+    private final NonNullList<ItemStack> m_inventory = NonNullList.withSize( INVENTORY_SIZE, ItemStack.EMPTY );
+    private final NonNullList<ItemStack> m_previousInventory = NonNullList.withSize( INVENTORY_SIZE, ItemStack.EMPTY );
     private final IItemHandlerModifiable m_itemHandler = new InvWrapper( this );
-    private boolean m_inventoryChanged;
-    private TurtleBrain m_brain;
-    private MoveState m_moveState;
+    private boolean m_inventoryChanged = false;
+    private TurtleBrain m_brain = new TurtleBrain( this );
+    private MoveState m_moveState = MoveState.NOT_MOVED;
     private ComputerFamily m_family;
 
     public TileTurtle()
@@ -78,15 +75,10 @@ public class TileTurtle extends TileComputerBase implements ITurtleTile, Default
 
     public TileTurtle( ComputerFamily family )
     {
-        m_inventory = NonNullList.withSize( INVENTORY_SIZE, ItemStack.EMPTY );
-        m_previousInventory = NonNullList.withSize( INVENTORY_SIZE, ItemStack.EMPTY );
-        m_inventoryChanged = false;
-        m_brain = new TurtleBrain( this );
-        m_moveState = MoveState.NOT_MOVED;
         m_family = family;
     }
 
-    public boolean hasMoved()
+    private boolean hasMoved()
     {
         return m_moveState == MoveState.MOVED;
     }
@@ -95,7 +87,7 @@ public class TileTurtle extends TileComputerBase implements ITurtleTile, Default
     protected ServerComputer createComputer( int instanceID, int id )
     {
         ServerComputer computer = new ServerComputer(
-            getWorld(), id, m_label, instanceID, getFamily(),
+            getWorld(), id, label, instanceID, getFamily(),
             ComputerCraft.terminalWidth_turtle, ComputerCraft.terminalHeight_turtle
         );
         computer.setPosition( getPos() );
@@ -224,18 +216,15 @@ public class TileTurtle extends TileComputerBase implements ITurtleTile, Default
     {
         super.update();
         m_brain.update();
-        synchronized( m_inventory )
+        if( !getWorld().isRemote && m_inventoryChanged )
         {
-            if( !getWorld().isRemote && m_inventoryChanged )
-            {
-                ServerComputer computer = getServerComputer();
-                if( computer != null ) computer.queueEvent( "turtle_inventory" );
+            ServerComputer computer = getServerComputer();
+            if( computer != null ) computer.queueEvent( "turtle_inventory" );
 
-                m_inventoryChanged = false;
-                for( int n = 0; n < getSizeInventory(); n++ )
-                {
-                    m_previousInventory.set( n, InventoryUtil.copyItem( getStackInSlot( n ) ) );
-                }
+            m_inventoryChanged = false;
+            for( int n = 0; n < getSizeInventory(); n++ )
+            {
+                m_previousInventory.set( n, getStackInSlot( n ).copy() );
             }
         }
     }
@@ -270,8 +259,8 @@ public class TileTurtle extends TileComputerBase implements ITurtleTile, Default
 
         // Read inventory
         NBTTagList nbttaglist = nbt.getTagList( "Items", Constants.NBT.TAG_COMPOUND );
-        m_inventory = NonNullList.withSize( INVENTORY_SIZE, ItemStack.EMPTY );
-        m_previousInventory = NonNullList.withSize( INVENTORY_SIZE, ItemStack.EMPTY );
+        m_inventory.clear();
+        m_previousInventory.clear();
         for( int i = 0; i < nbttaglist.tagCount(); i++ )
         {
             NBTTagCompound tag = nbttaglist.getCompoundTagAt( i );
@@ -279,7 +268,7 @@ public class TileTurtle extends TileComputerBase implements ITurtleTile, Default
             if( slot < getSizeInventory() )
             {
                 m_inventory.set( slot, new ItemStack( tag ) );
-                m_previousInventory.set( slot, InventoryUtil.copyItem( m_inventory.get( slot ) ) );
+                m_previousInventory.set( slot, m_inventory.get( slot ).copy() );
             }
         }
 
@@ -382,7 +371,7 @@ public class TileTurtle extends TileComputerBase implements ITurtleTile, Default
         return m_family;
     }
 
-    public void setOwningPlayer( GameProfile player )
+    void setOwningPlayer( GameProfile player )
     {
         m_brain.setOwningPlayer( player );
         markDirty();
@@ -410,109 +399,76 @@ public class TileTurtle extends TileComputerBase implements ITurtleTile, Default
     @Override
     public ItemStack getStackInSlot( int slot )
     {
-        if( slot >= 0 && slot < INVENTORY_SIZE )
-        {
-            synchronized( m_inventory )
-            {
-                return m_inventory.get( slot );
-            }
-        }
-        return ItemStack.EMPTY;
+        return slot >= 0 && slot < INVENTORY_SIZE ? m_inventory.get( slot ) : ItemStack.EMPTY;
     }
 
     @Nonnull
     @Override
     public ItemStack removeStackFromSlot( int slot )
     {
-        synchronized( m_inventory )
-        {
-            ItemStack result = getStackInSlot( slot );
-            setInventorySlotContents( slot, ItemStack.EMPTY );
-            return result;
-        }
+        ItemStack result = getStackInSlot( slot );
+        setInventorySlotContents( slot, ItemStack.EMPTY );
+        return result;
     }
 
     @Nonnull
     @Override
     public ItemStack decrStackSize( int slot, int count )
     {
-        if( count == 0 )
+        if( count == 0 ) return ItemStack.EMPTY;
+
+        ItemStack stack = getStackInSlot( slot );
+        if( stack.isEmpty() ) return ItemStack.EMPTY;
+
+        if( stack.getCount() <= count )
         {
-            return ItemStack.EMPTY;
+            setInventorySlotContents( slot, ItemStack.EMPTY );
+            return stack;
         }
 
-        synchronized( m_inventory )
-        {
-            ItemStack stack = getStackInSlot( slot );
-            if( stack.isEmpty() )
-            {
-                return ItemStack.EMPTY;
-            }
-
-            if( stack.getCount() <= count )
-            {
-                setInventorySlotContents( slot, ItemStack.EMPTY );
-                return stack;
-            }
-
-            ItemStack part = stack.splitStack( count );
-            onInventoryDefinitelyChanged();
-            return part;
-        }
+        ItemStack part = stack.splitStack( count );
+        onInventoryDefinitelyChanged();
+        return part;
     }
 
     @Override
     public void setInventorySlotContents( int i, @Nonnull ItemStack stack )
     {
-        if( i >= 0 && i < INVENTORY_SIZE )
+        if( i >= 0 && i < INVENTORY_SIZE && !InventoryUtil.areItemsEqual( stack, m_inventory.get( i ) ) )
         {
-            synchronized( m_inventory )
-            {
-                if( !InventoryUtil.areItemsEqual( stack, m_inventory.get( i ) ) )
-                {
-                    m_inventory.set( i, stack );
-                    onInventoryDefinitelyChanged();
-                }
-            }
+            m_inventory.set( i, stack );
+            onInventoryDefinitelyChanged();
         }
     }
 
     @Override
     public void clear()
     {
-        synchronized( m_inventory )
+        boolean changed = false;
+        for( int i = 0; i < INVENTORY_SIZE; i++ )
         {
-            boolean changed = false;
-            for( int i = 0; i < INVENTORY_SIZE; i++ )
+            if( !m_inventory.get( i ).isEmpty() )
             {
-                if( !m_inventory.get( i ).isEmpty() )
-                {
-                    m_inventory.set( i, ItemStack.EMPTY );
-                    changed = true;
-                }
-            }
-            if( changed )
-            {
-                onInventoryDefinitelyChanged();
+                m_inventory.set( i, ItemStack.EMPTY );
+                changed = true;
             }
         }
+
+        if( changed ) onInventoryDefinitelyChanged();
     }
 
     @Override
     public void markDirty()
     {
         super.markDirty();
-        synchronized( m_inventory )
+        if( !m_inventoryChanged )
         {
-            if( !m_inventoryChanged )
+            for( int n = 0; n < getSizeInventory(); n++ )
             {
-                for( int n = 0; n < getSizeInventory(); n++ )
+                if( !ItemStack.areItemStacksEqual( getStackInSlot( n ), m_previousInventory.get( n ) ) )
                 {
-                    if( !ItemStack.areItemStacksEqual( getStackInSlot( n ), m_previousInventory.get( n ) ) )
-                    {
-                        m_inventoryChanged = true;
-                        break;
-                    }
+                    m_inventoryChanged = true;
+                    break;
                 }
             }
         }
@@ -574,8 +530,8 @@ public class TileTurtle extends TileComputerBase implements ITurtleTile, Default
     public void transferStateFrom( TileTurtle copy )
     {
         super.transferStateFrom( copy );
-        m_inventory = copy.m_inventory;
-        m_previousInventory = copy.m_previousInventory;
+        Collections.copy( m_inventory, copy.m_inventory );
+        Collections.copy( m_previousInventory, copy.m_previousInventory );
         m_inventoryChanged = copy.m_inventoryChanged;
         m_brain = copy.m_brain;
         m_brain.setOwner( this );

src/main/java/dan200/computercraft/shared/turtle/core/TurtleBrain.java

@@ -20,10 +20,7 @@ import dan200.computercraft.shared.computer.blocks.TileComputerBase;
 import dan200.computercraft.shared.computer.core.ComputerFamily;
 import dan200.computercraft.shared.computer.core.ServerComputer;
 import dan200.computercraft.shared.turtle.blocks.TileTurtle;
-import dan200.computercraft.shared.util.Colour;
-import dan200.computercraft.shared.util.ColourUtils;
-import dan200.computercraft.shared.util.Holiday;
-import dan200.computercraft.shared.util.HolidayUtil;
+import dan200.computercraft.shared.util.*;
 import net.minecraft.block.Block;
 import net.minecraft.entity.Entity;
 import net.minecraft.entity.MoverType;
@@ -40,6 +37,7 @@ import net.minecraft.util.math.Vec3d;
 import net.minecraft.world.World;
 import net.minecraftforge.common.util.Constants;
 import net.minecraftforge.items.IItemHandlerModifiable;
+import net.minecraftforge.items.wrapper.InvWrapper;
 
 import javax.annotation.Nonnull;
 import java.util.*;
@@ -53,6 +51,9 @@ public class TurtleBrain implements ITurtleAccess
     private ComputerProxy m_proxy;
     private GameProfile m_owningPlayer;
 
+    private final IInventory m_inventory = (InventoryDelegate) () -> m_owner;
+    private final IItemHandlerModifiable m_inventoryWrapper = new InvWrapper( m_inventory );
+
     private Queue<TurtleCommandQueueEntry> m_commandQueue = new ArrayDeque<>();
     private int m_commandsIssued = 0;
 
@@ -531,14 +532,14 @@ public class TurtleBrain implements ITurtleAccess
     @Override
     public IInventory getInventory()
     {
-        return m_owner;
+        return m_inventory;
     }
 
     @Nonnull
     @Override
     public IItemHandlerModifiable getItemHandler()
     {
-        return m_owner.getItemHandler();
+        return m_inventoryWrapper;
     }
 
     @Override
@@ -908,14 +909,14 @@ public class TurtleBrain implements ITurtleAccess
             else
             {
                 computer.queueEvent( "turtle_response", new Object[] {
-                    callbackID, true
+                    callbackID, true,
                 } );
             }
         }
         else
         {
             computer.queueEvent( "turtle_response", new Object[] {
-                callbackID, false, result != null ? result.getErrorMessage() : null
+                callbackID, false, result != null ? result.getErrorMessage() : null,
             } );
         }
     }

src/main/java/dan200/computercraft/shared/turtle/core/TurtlePlaceCommand.java

@@ -65,7 +65,6 @@ public class TurtlePlaceCommand implements ITurtleCommand
 
         // Remember old block
         EnumFacing direction = m_direction.toWorldDir( turtle );
-        World world = turtle.getWorld();
         BlockPos coordinates = turtle.getPosition().offset( direction );
 
         // Create a fake player, and orient it appropriately

src/main/java/dan200/computercraft/shared/turtle/inventory/ContainerTurtle.java

@@ -26,8 +26,8 @@ public class ContainerTurtle extends Container implements IContainerComputer
 {
     private static final int PROGRESS_ID_SELECTED_SLOT = 0;
 
-    public final int m_playerInvStartY;
-    public final int m_turtleInvStartX;
+    public final int playerInvStartY;
+    public final int turtleInvStartX;
 
     private final ITurtleAccess m_turtle;
     private IComputer m_computer;
@@ -36,8 +36,8 @@ public class ContainerTurtle extends Container implements IContainerComputer
 
     protected ContainerTurtle( IInventory playerInventory, ITurtleAccess turtle, int playerInvStartY, int turtleInvStartX )
     {
-        m_playerInvStartY = playerInvStartY;
-        m_turtleInvStartX = turtleInvStartX;
+        this.playerInvStartY = playerInvStartY;
+        this.turtleInvStartX = turtleInvStartX;
 
         m_turtle = turtle;
         m_selectedSlot = m_turtle.getWorld().isRemote ? 0 : m_turtle.getSelectedSlot();

src/main/java/dan200/computercraft/shared/turtle/items/ItemTurtleLegacy.java

@@ -73,7 +73,10 @@ public class ItemTurtleLegacy extends ItemTurtleBase
     }
 
     @Override
-    public ResourceLocation getOverlay( @Nonnull ItemStack stack ) { return null; }
+    public ResourceLocation getOverlay( @Nonnull ItemStack stack )
+    {
+        return null;
+    }
 
     @Override
     public int getFuelLevel( @Nonnull ItemStack stack )

src/main/java/dan200/computercraft/shared/turtle/upgrades/TurtleHoe.java

@@ -54,7 +54,7 @@ public class TurtleHoe extends TurtleTool
     {
         if( verb == TurtleVerb.Dig )
         {
-            ItemStack hoe = m_item.copy();
+            ItemStack hoe = item.copy();
             ItemStack remainder = TurtlePlaceCommand.deploy( hoe, turtle, direction, null, null );
             if( remainder != hoe )
             {

src/main/java/dan200/computercraft/shared/turtle/upgrades/TurtleShovel.java

@@ -60,7 +60,7 @@ public class TurtleShovel extends TurtleTool
     {
         if( verb == TurtleVerb.Dig )
         {
-            ItemStack shovel = m_item.copy();
+            ItemStack shovel = item.copy();
             ItemStack remainder = TurtlePlaceCommand.deploy( shovel, turtle, direction, null, null );
             if( remainder != shovel )
             {

src/main/java/dan200/computercraft/shared/turtle/upgrades/TurtleTool.java

@@ -48,18 +48,18 @@ import java.util.function.Function;
 
 public class TurtleTool extends AbstractTurtleUpgrade
 {
-    protected ItemStack m_item;
+    protected final ItemStack item;
 
     public TurtleTool( ResourceLocation id, int legacyID, String adjective, Item item )
     {
         super( id, legacyID, TurtleUpgradeType.Tool, adjective, item );
-        m_item = new ItemStack( item, 1, 0 );
+        this.item = new ItemStack( item, 1, 0 );
     }
 
     public TurtleTool( ResourceLocation id, int legacyID, Item item )
     {
         super( id, legacyID, TurtleUpgradeType.Tool, item );
-        m_item = new ItemStack( item, 1, 0 );
+        this.item = new ItemStack( item, 1, 0 );
     }
 
     @Nonnull
@@ -76,7 +76,7 @@ public class TurtleTool extends AbstractTurtleUpgrade
         );
         Minecraft mc = Minecraft.getMinecraft();
         return Pair.of(
-            mc.getRenderItem().getItemModelMesher().getItemModel( m_item ),
+            mc.getRenderItem().getItemModelMesher().getItemModel( item ),
             transform
         );
     }
@@ -124,7 +124,7 @@ public class TurtleTool extends AbstractTurtleUpgrade
         if( hit != null )
         {
             // Load up the turtle's inventory
-            ItemStack stackCopy = m_item.copy();
+            ItemStack stackCopy = item.copy();
             turtlePlayer.loadInventory( stackCopy );
 
             Entity hitEntity = hit.getKey();
@@ -202,7 +202,7 @@ public class TurtleTool extends AbstractTurtleUpgrade
         IBlockState state = world.getBlockState( blockPosition );
 
         TurtlePlayer turtlePlayer = TurtlePlaceCommand.createPlayer( turtle, turtlePosition, direction );
-        turtlePlayer.loadInventory( m_item.copy() );
+        turtlePlayer.loadInventory( item.copy() );
 
         if( ComputerCraft.turtlesObeyBlockProtection )
         {
@@ -246,7 +246,7 @@ public class TurtleTool extends AbstractTurtleUpgrade
         boolean canHarvest = state.getBlock().canHarvestBlock( world, blockPosition, turtlePlayer );
         boolean canBreak = state.getBlock().removedByPlayer( state, world, blockPosition, turtlePlayer, canHarvest );
         if( canBreak ) state.getBlock().onPlayerDestroy( world, blockPosition, state );
-        if( canHarvest )
+        if( canHarvest && canBreak )
         {
             state.getBlock().harvestBlock( world, turtlePlayer, blockPosition, state, tile, turtlePlayer.getHeldItemMainhand() );
         }

src/main/java/dan200/computercraft/shared/util/ColourUtils.java

@@ -20,7 +20,7 @@ public final class ColourUtils
         "dyeBlack", "dyeRed", "dyeGreen", "dyeBrown",
         "dyeBlue", "dyePurple", "dyeCyan", "dyeLightGray",
         "dyeGray", "dyePink", "dyeLime", "dyeYellow",
-        "dyeLightBlue", "dyeMagenta", "dyeOrange", "dyeWhite"
+        "dyeLightBlue", "dyeMagenta", "dyeOrange", "dyeWhite",
     };
 
     private static int[] ids;

src/main/java/dan200/computercraft/shared/util/DropConsumer.java

@@ -14,8 +14,6 @@ import net.minecraft.util.math.AxisAlignedBB;
 import net.minecraft.util.math.BlockPos;
 import net.minecraft.world.World;
 import net.minecraftforge.event.entity.EntityJoinWorldEvent;
-import net.minecraftforge.event.entity.living.LivingDropsEvent;
-import net.minecraftforge.event.world.BlockEvent;
 import net.minecraftforge.fml.common.Mod;
 import net.minecraftforge.fml.common.eventhandler.EventPriority;
 import net.minecraftforge.fml.common.eventhandler.SubscribeEvent;
@@ -35,7 +33,6 @@ public final class DropConsumer
     private static Function<ItemStack, ItemStack> dropConsumer;
     private static List<ItemStack> remainingDrops;
     private static WeakReference<World> dropWorld;
-    private static BlockPos dropPos;
     private static AxisAlignedBB dropBounds;
     private static WeakReference<Entity> dropEntity;
 
@@ -45,7 +42,6 @@ public final class DropConsumer
         remainingDrops = new ArrayList<>();
         dropEntity = new WeakReference<>( entity );
         dropWorld = new WeakReference<>( entity.world );
-        dropPos = null;
         dropBounds = new AxisAlignedBB( entity.getPosition() ).grow( 2, 2, 2 );
 
         entity.captureDrops = true;
@@ -54,10 +50,9 @@ public final class DropConsumer
     public static void set( World world, BlockPos pos, Function<ItemStack, ItemStack> consumer )
     {
         dropConsumer = consumer;
-        remainingDrops = new ArrayList<>();
+        remainingDrops = new ArrayList<>( 2 );
         dropEntity = null;
         dropWorld = new WeakReference<>( world );
-        dropPos = pos;
         dropBounds = new AxisAlignedBB( pos ).grow( 2, 2, 2 );
     }
 
@@ -83,7 +78,6 @@ public final class DropConsumer
         remainingDrops = null;
         dropEntity = null;
         dropWorld = null;
-        dropPos = null;
         dropBounds = null;
 
         return remainingStacks;
@@ -95,34 +89,7 @@ public final class DropConsumer
         if( !remaining.isEmpty() ) remainingDrops.add( remaining );
     }
 
-    @SubscribeEvent( priority = EventPriority.LOWEST )
-    public static void onEntityLivingDrops( LivingDropsEvent event )
-    {
-        // Capture any mob drops for the current entity
-        if( dropEntity != null && event.getEntity() == dropEntity.get() )
-        {
-            List<EntityItem> drops = event.getDrops();
-            for( EntityItem entityItem : drops ) handleDrops( entityItem.getItem() );
-            drops.clear();
-        }
-    }
-
-    @SubscribeEvent( priority = EventPriority.LOWEST )
-    public static void onHarvestDrops( BlockEvent.HarvestDropsEvent event )
-    {
-        // Capture block drops for the current entity
-        if( dropWorld != null && dropWorld.get() == event.getWorld()
-            && dropPos != null && dropPos.equals( event.getPos() ) )
-        {
-            for( ItemStack item : event.getDrops() )
-            {
-                if( event.getWorld().rand.nextFloat() < event.getDropChance() ) handleDrops( item );
-            }
-            event.getDrops().clear();
-        }
-    }
-
-    @SubscribeEvent( priority = EventPriority.LOWEST )
+    @SubscribeEvent( priority = EventPriority.HIGHEST )
     public static void onEntitySpawn( EntityJoinWorldEvent event )
     {
         // Capture any nearby item spawns

src/main/java/dan200/computercraft/shared/util/InventoryDelegate.java

@@ -0,0 +1,146 @@
+/*
+ * 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.shared.util;
+
+import net.minecraft.entity.player.EntityPlayer;
+import net.minecraft.inventory.IInventory;
+import net.minecraft.item.ItemStack;
+import net.minecraft.util.text.ITextComponent;
+
+import javax.annotation.Nonnull;
+
+/**
+ * Provides a delegate over inventories.
+ *
+ * This may be used both on {@link net.minecraft.tileentity.TileEntity}s to redirect the inventory to another tile,
+ * and by other interfaces to have inventories which change their backing store.
+ */
+@FunctionalInterface
+public interface InventoryDelegate extends IInventory
+{
+    IInventory getInventory();
+
+    @Override
+    default int getSizeInventory()
+    {
+        return getInventory().getSizeInventory();
+    }
+
+    @Override
+    default boolean isEmpty()
+    {
+        return getInventory().isEmpty();
+    }
+
+    @Nonnull
+    @Override
+    default ItemStack getStackInSlot( int slot )
+    {
+        return getInventory().getStackInSlot( slot );
+    }
+
+    @Nonnull
+    @Override
+    default ItemStack decrStackSize( int slot, int count )
+    {
+        return getInventory().decrStackSize( slot, count );
+    }
+
+    @Nonnull
+    @Override
+    default ItemStack removeStackFromSlot( int slot )
+    {
+        return getInventory().removeStackFromSlot( slot );
+    }
+
+    @Override
+    default void setInventorySlotContents( int slot, ItemStack stack )
+    {
+        getInventory().setInventorySlotContents( slot, stack );
+    }
+
+    @Override
+    default int getInventoryStackLimit()
+    {
+        return getInventory().getInventoryStackLimit();
+    }
+
+    @Override
+    default void markDirty()
+    {
+        getInventory().markDirty();
+    }
+
+    @Override
+    default boolean isUsableByPlayer( @Nonnull EntityPlayer player )
+    {
+        return getInventory().isUsableByPlayer( player );
+    }
+
+    @Override
+    default void openInventory( @Nonnull EntityPlayer player )
+    {
+        getInventory().openInventory( player );
+    }
+
+    @Override
+    default void closeInventory( @Nonnull EntityPlayer player )
+    {
+        getInventory().closeInventory( player );
+    }
+
+    @Override
+    default boolean isItemValidForSlot( int slot, @Nonnull ItemStack stack )
+    {
+        return getInventory().isItemValidForSlot( slot, stack );
+    }
+
+    @Override
+    default int getField( int id )
+    {
+        return getInventory().getField( id );
+    }
+
+    @Override
+    default void setField( int id, int val )
+    {
+        getInventory().setField( id, val );
+
+    }
+
+    @Override
+    default int getFieldCount()
+    {
+        return getInventory().getFieldCount();
+    }
+
+    @Override
+    default void clear()
+    {
+        getInventory().clear();
+    }
+
+    @Nonnull
+    @Override
+    default String getName()
+    {
+        return getInventory().getName();
+    }
+
+    @Override
+    default boolean hasCustomName()
+    {
+        return getInventory().hasCustomName();
+    }
+
+    @Nonnull
+    @Override
+    default ITextComponent getDisplayName()
+    {
+        return getInventory().getDisplayName();
+    }
+}

src/main/java/dan200/computercraft/shared/util/InventoryUtil.java

@@ -69,12 +69,6 @@ public final class InventoryUtil
         return shareTagA.equals( shareTagB );
     }
 
-    @Nonnull
-    public static ItemStack copyItem( @Nonnull ItemStack a )
-    {
-        return a.copy();
-    }
-
     // Methods for finding inventories:
 
     public static IItemHandler getInventory( World world, BlockPos pos, EnumFacing side )

src/main/java/dan200/computercraft/shared/util/Palette.java

@@ -72,12 +72,11 @@ public class Palette
 
     public static double[] decodeRGB8( int rgb )
     {
-        return new double[]
-            {
-                ((rgb >> 16) & 0xFF) / 255.0f,
-                ((rgb >> 8) & 0xFF) / 255.0f,
-                (rgb & 0xFF) / 255.0f
-            };
+        return new double[] {
+            ((rgb >> 16) & 0xFF) / 255.0f,
+            ((rgb >> 8) & 0xFF) / 255.0f,
+            (rgb & 0xFF) / 255.0f,
+        };
     }
 
     public NBTTagCompound writeToNBT( NBTTagCompound nbt )

src/main/resources/assets/computercraft/lua/bios.lua

@@ -1,48 +1,19 @@
-local native_select, native_type = select, type
-
---- Expect an argument to have a specific type.
+-- Load in expect from the module path.
 --
--- @tparam int index The 1-based argument index.
--- @param value The argument's value.
--- @tparam string ... The allowed types of the argument.
--- @throws If the value is not one of the allowed types.
-local function expect(index, value, ...)
-    local t = native_type(value)
-    for i = 1, native_select("#", ...) do
-        if t == native_select(i, ...) then return true end
-    end
+-- Ideally we'd use require, but that is part of the shell, and so is not
+-- available to the BIOS or any APIs. All APIs load this using dofile, but that
+-- has not been defined at this point.
+local expect
 
-    local types = table.pack(...)
-    for i = types.n, 1, -1 do
-        if types[i] == "nil" then table.remove(types, i) end
-    end
+do
+    local h = fs.open("rom/modules/main/cc/expect.lua", "r")
+    local f, err = loadstring(h.readAll(), "@expect.lua")
+    h.close()
 
-    local type_names
-    if #types <= 1 then
-        type_names = tostring(...)
-    else
-        type_names = table.concat(types, ", ", 1, #types - 1) .. " or " .. types[#types]
-    end
-
-    -- If we can determine the function name with a high level of confidence, try to include it.
-    local name
-    if native_type(debug) == "table" and native_type(debug.getinfo) == "function" then
-        local ok, info = pcall(debug.getinfo, 3, "nS")
-        if ok and info.name and #info.name ~= "" and info.what ~= "C" then name = info.name end
-    end
-
-    if name then
-        error( ("bad argument #%d to '%s' (expected %s, got %s)"):format(index, name, type_names, t), 3 )
-    else
-        error( ("bad argument #%d (expected %s, got %s)"):format(index, type_names, t), 3 )
-    end
+    if not f then error(err) end
+    expect = f().expect
 end
 
--- We expose expect in the global table as APIs need to access it, but give it
--- a non-identifier name - meaning it does not show up in auto-completion.
--- expect is an internal function, and should not be used by users.
-_G["~expect"] = expect
-
 if _VERSION == "Lua 5.1" then
     -- If we're on Lua 5.1, install parts of the Lua 5.2/5.3 API so that programs can be written against it
     local type = type
@@ -568,23 +539,28 @@ function read( _sReplaceChar, _tHistory, _fnComplete, _sDefault )
     return sLine
 end
 
-function loadfile( _sFile, _tEnv )
-    expect(1, _sFile, "string")
-    expect(2, _tEnv, "table", "nil")
-
-    local file = fs.open( _sFile, "r" )
-    if file then
-        local func, err = load( file.readAll(), "@" .. fs.getName( _sFile ), "t", _tEnv )
-        file.close()
-        return func, err
+function loadfile( filename, mode, env )
+    -- Support the previous `loadfile(filename, env)` form instead.
+    if type(mode) == "table" and env == nil then
+        mode, env = nil, mode
     end
-    return nil, "File not found"
+
+    expect(1, filename, "string")
+    expect(2, mode, "string", "nil")
+    expect(3, env, "table", "nil")
+
+    local file = fs.open( filename, "r" )
+    if not file then return nil, "File not found" end
+
+    local func, err = load( file.readAll(), "@" .. fs.getName( filename ), mode, env )
+    file.close()
+    return func, err
 end
 
 function dofile( _sFile )
     expect(1, _sFile, "string")
 
-    local fnFile, e = loadfile( _sFile, _G )
+    local fnFile, e = loadfile( _sFile, nil, _G )
     if fnFile then
         return fnFile()
     else
@@ -600,7 +576,7 @@ function os.run( _tEnv, _sPath, ... )
     local tArgs = table.pack( ... )
     local tEnv = _tEnv
     setmetatable( tEnv, { __index = _G } )
-    local fnFile, err = loadfile( _sPath, tEnv )
+    local fnFile, err = loadfile( _sPath, nil, tEnv )
     if fnFile then
         local ok, err = pcall( function()
             fnFile( table.unpack( tArgs, 1, tArgs.n ) )
@@ -634,7 +610,7 @@ function os.loadAPI( _sPath )
 
     local tEnv = {}
     setmetatable( tEnv, { __index = _G } )
-    local fnAPI, err = loadfile( _sPath, tEnv )
+    local fnAPI, err = loadfile( _sPath, nil, tEnv )
     if fnAPI then
         local ok, err = pcall( fnAPI )
         if not ok then

src/main/resources/assets/computercraft/lua/rom/apis/colors.lua

@@ -1,4 +1,4 @@
-local expect = _G["~expect"]
+local expect = dofile("rom/modules/main/cc/expect.lua").expect
 
 -- Colors
 white = 1

src/main/resources/assets/computercraft/lua/rom/apis/gps.lua

@@ -1,4 +1,4 @@
-local expect = _G["~expect"]
+local expect = dofile("rom/modules/main/cc/expect.lua").expect
 
 CHANNEL_GPS = 65534
 

src/main/resources/assets/computercraft/lua/rom/apis/help.lua

@@ -1,4 +1,4 @@
-local expect = _G["~expect"]
+local expect = dofile("rom/modules/main/cc/expect.lua").expect
 
 local sPath = "/rom/help"
 

src/main/resources/assets/computercraft/lua/rom/apis/io.lua

@@ -1,6 +1,6 @@
 -- Definition for the IO API
 
-local expect, typeOf = _G["~expect"], _G.type
+local expect, typeOf = dofile("rom/modules/main/cc/expect.lua").expect, _G.type
 
 --- If we return nil then close the file, as we've reached the end.
 -- We use this weird wrapper function as we wish to preserve the varargs

src/main/resources/assets/computercraft/lua/rom/apis/keys.lua

@@ -1,7 +1,7 @@
 -- Minecraft key code bindings
 -- See http://www.minecraftwiki.net/wiki/Key_codes for more info
 
-local expect = _G["~expect"]
+local expect = dofile("rom/modules/main/cc/expect.lua").expect
 
 local tKeys = {
     nil,	 	"one", 		"two", 		"three", 	"four",			-- 1

src/main/resources/assets/computercraft/lua/rom/apis/paintutils.lua

@@ -1,4 +1,4 @@
-local expect = _G["~expect"]
+local expect = dofile("rom/modules/main/cc/expect.lua").expect
 
 local function drawPixelInternal( xPos, yPos )
     term.setCursorPos( xPos, yPos )

src/main/resources/assets/computercraft/lua/rom/apis/peripheral.lua

@@ -1,4 +1,4 @@
-local expect = _G["~expect"]
+local expect = dofile("rom/modules/main/cc/expect.lua").expect
 
 local native = peripheral
 

src/main/resources/assets/computercraft/lua/rom/apis/rednet.lua

@@ -1,4 +1,4 @@
-local expect = _G["~expect"]
+local expect = dofile("rom/modules/main/cc/expect.lua").expect
 
 CHANNEL_BROADCAST = 65535
 CHANNEL_REPEAT = 65533

src/main/resources/assets/computercraft/lua/rom/apis/settings.lua

@@ -1,4 +1,4 @@
-local expect = _G["~expect"]
+local expect = dofile("rom/modules/main/cc/expect.lua").expect
 
 local tSettings = {}
 

src/main/resources/assets/computercraft/lua/rom/apis/term.lua

@@ -1,4 +1,4 @@
-local expect = _G["~expect"]
+local expect = dofile("rom/modules/main/cc/expect.lua").expect
 
 local native = (term.native and term.native()) or term
 local redirectTarget = native