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72beeeeaaa
janet/src/core/fiber.c
Calvin Rose 72beeeeaaa Move funcenv verification to runtime. 
Lazy verification makes it easier to not leave funcenvs
in an invalid state, as well as be more precise with the validation.
We needed to verify the FuncEnvs actually pointed to a stack frame if
they were of the "on-stack" variant. There was some minor checking
before, but it was not enough to prevent func envs from pointing to
memory that was off of the fiber stack, overlapping stack frames, etc.
2020-04-06 10:58:47 -05:00

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/*
* Copyright (c) 2020 Calvin Rose
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to
* deal in the Software without restriction, including without limitation the
* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/
#ifndef JANET_AMALG
#include "features.h"
#include <janet.h>
#include "fiber.h"
#include "state.h"
#include "gc.h"
#include "util.h"
#endif
static void fiber_reset(JanetFiber *fiber) {
fiber->maxstack = JANET_STACK_MAX;
fiber->frame = 0;
fiber->stackstart = JANET_FRAME_SIZE;
fiber->stacktop = JANET_FRAME_SIZE;
fiber->child = NULL;
fiber->flags = JANET_FIBER_MASK_YIELD | JANET_FIBER_RESUME_NO_USEVAL | JANET_FIBER_RESUME_NO_SKIP;
fiber->env = NULL;
janet_fiber_set_status(fiber, JANET_STATUS_NEW);
}
static JanetFiber *fiber_alloc(int32_t capacity) {
Janet *data;
JanetFiber *fiber = janet_gcalloc(JANET_MEMORY_FIBER, sizeof(JanetFiber));
if (capacity < 32) {
capacity = 32;
}
fiber->capacity = capacity;
data = malloc(sizeof(Janet) * (size_t) capacity);
if (NULL == data) {
JANET_OUT_OF_MEMORY;
}
janet_vm_next_collection += sizeof(Janet) * capacity;
fiber->data = data;
return fiber;
}
/* Create a new fiber with argn values on the stack by reusing a fiber. */
JanetFiber *janet_fiber_reset(JanetFiber *fiber, JanetFunction *callee, int32_t argc, const Janet *argv) {
int32_t newstacktop;
fiber_reset(fiber);
if (argc) {
newstacktop = fiber->stacktop + argc;
if (newstacktop >= fiber->capacity) {
janet_fiber_setcapacity(fiber, 2 * newstacktop);
}
if (argv) {
memcpy(fiber->data + fiber->stacktop, argv, argc * sizeof(Janet));
} else {
/* If argv not given, fill with nil */
for (int32_t i = 0; i < argc; i++) {
fiber->data[fiber->stacktop + i] = janet_wrap_nil();
}
}
fiber->stacktop = newstacktop;
}
if (janet_fiber_funcframe(fiber, callee)) return NULL;
janet_fiber_frame(fiber)->flags |= JANET_STACKFRAME_ENTRANCE;
return fiber;
}
/* Create a new fiber with argn values on the stack. */
JanetFiber *janet_fiber(JanetFunction *callee, int32_t capacity, int32_t argc, const Janet *argv) {
return janet_fiber_reset(fiber_alloc(capacity), callee, argc, argv);
}
/* Ensure that the fiber has enough extra capacity */
void janet_fiber_setcapacity(JanetFiber *fiber, int32_t n) {
Janet *newData = realloc(fiber->data, sizeof(Janet) * n);
if (NULL == newData) {
JANET_OUT_OF_MEMORY;
}
fiber->data = newData;
fiber->capacity = n;
}
/* Grow fiber if needed */
static void janet_fiber_grow(JanetFiber *fiber, int32_t needed) {
int32_t cap = needed > (INT32_MAX / 2) ? INT32_MAX : 2 * needed;
janet_fiber_setcapacity(fiber, cap);
}
/* Push a value on the next stack frame */
void janet_fiber_push(JanetFiber *fiber, Janet x) {
if (fiber->stacktop == INT32_MAX) janet_panic("stack overflow");
if (fiber->stacktop >= fiber->capacity) {
janet_fiber_grow(fiber, fiber->stacktop);
}
fiber->data[fiber->stacktop++] = x;
}
/* Push 2 values on the next stack frame */
void janet_fiber_push2(JanetFiber *fiber, Janet x, Janet y) {
if (fiber->stacktop >= INT32_MAX - 1) janet_panic("stack overflow");
int32_t newtop = fiber->stacktop + 2;
if (newtop > fiber->capacity) {
janet_fiber_grow(fiber, newtop);
}
fiber->data[fiber->stacktop] = x;
fiber->data[fiber->stacktop + 1] = y;
fiber->stacktop = newtop;
}
/* Push 3 values on the next stack frame */
void janet_fiber_push3(JanetFiber *fiber, Janet x, Janet y, Janet z) {
if (fiber->stacktop >= INT32_MAX - 2) janet_panic("stack overflow");
int32_t newtop = fiber->stacktop + 3;
if (newtop > fiber->capacity) {
janet_fiber_grow(fiber, newtop);
}
fiber->data[fiber->stacktop] = x;
fiber->data[fiber->stacktop + 1] = y;
fiber->data[fiber->stacktop + 2] = z;
fiber->stacktop = newtop;
}
/* Push an array on the next stack frame */
void janet_fiber_pushn(JanetFiber *fiber, const Janet *arr, int32_t n) {
if (fiber->stacktop > INT32_MAX - n) janet_panic("stack overflow");
int32_t newtop = fiber->stacktop + n;
if (newtop > fiber->capacity) {
janet_fiber_grow(fiber, newtop);
}
safe_memcpy(fiber->data + fiber->stacktop, arr, n * sizeof(Janet));
fiber->stacktop = newtop;
}
/* Create a struct with n values. If n is odd, the last value is ignored. */
static Janet make_struct_n(const Janet *args, int32_t n) {
int32_t i = 0;
JanetKV *st = janet_struct_begin(n & (~1));
for (; i < n; i += 2) {
janet_struct_put(st, args[i], args[i + 1]);
}
return janet_wrap_struct(janet_struct_end(st));
}
/* Push a stack frame to a fiber */
int janet_fiber_funcframe(JanetFiber *fiber, JanetFunction *func) {
JanetStackFrame *newframe;
int32_t i;
int32_t oldtop = fiber->stacktop;
int32_t oldframe = fiber->frame;
int32_t nextframe = fiber->stackstart;
int32_t nextstacktop = nextframe + func->def->slotcount + JANET_FRAME_SIZE;
int32_t next_arity = fiber->stacktop - fiber->stackstart;
/* Check strict arity before messing with state */
if (next_arity < func->def->min_arity) return 1;
if (next_arity > func->def->max_arity) return 1;
if (fiber->capacity < nextstacktop) {
janet_fiber_setcapacity(fiber, 2 * nextstacktop);
}
/* Nil unset stack arguments (Needed for gc correctness) */
for (i = fiber->stacktop; i < nextstacktop; ++i) {
fiber->data[i] = janet_wrap_nil();
}
/* Set up the next frame */
fiber->frame = nextframe;
fiber->stacktop = fiber->stackstart = nextstacktop;
newframe = janet_fiber_frame(fiber);
newframe->prevframe = oldframe;
newframe->pc = func->def->bytecode;
newframe->func = func;
newframe->env = NULL;
newframe->flags = 0;
/* Check varargs */
if (func->def->flags & JANET_FUNCDEF_FLAG_VARARG) {
int32_t tuplehead = fiber->frame + func->def->arity;
int st = func->def->flags & JANET_FUNCDEF_FLAG_STRUCTARG;
if (tuplehead >= oldtop) {
fiber->data[tuplehead] = st
? make_struct_n(NULL, 0)
: janet_wrap_tuple(janet_tuple_n(NULL, 0));
} else {
fiber->data[tuplehead] = st
? make_struct_n(
fiber->data + tuplehead,
oldtop - tuplehead)
: janet_wrap_tuple(janet_tuple_n(
fiber->data + tuplehead,
oldtop - tuplehead));
}
}
/* Good return */
return 0;
}
/* If a frame has a closure environment, detach it from
* the stack and have it keep its own values */
static void janet_env_detach(JanetFuncEnv *env) {
/* Check for closure environment */
if (env) {
janet_env_valid(env);
int32_t len = env->length;
size_t s = sizeof(Janet) * (size_t) len;
Janet *vmem = malloc(s);
janet_vm_next_collection += (uint32_t) s;
if (NULL == vmem) {
JANET_OUT_OF_MEMORY;
}
Janet *values = env->as.fiber->data + env->offset;
safe_memcpy(vmem, values, s);
uint32_t *bitset = janet_stack_frame(values)->func->def->closure_bitset;
if (bitset) {
/* Clear unneeded references in closure environment */
for (int32_t i = 0; i < len; i += 32) {
uint32_t mask = ~(bitset[i >> 5]);
int32_t maxj = i + 32 > len ? len : i + 32;
for (int32_t j = i; j < maxj; j++) {
if (mask & 1) vmem[j] = janet_wrap_nil();
mask >>= 1;
}
}
}
env->offset = 0;
env->as.values = vmem;
}
}
/* Validate potentially untrusted func env (unmarshalled envs are difficult to verify) */
int janet_env_valid(JanetFuncEnv *env) {
if (env->offset < 0) {
int32_t real_offset = -(env->offset);
JanetFiber *fiber = env->as.fiber;
int32_t i = fiber->frame;
while (i > 0) {
JanetStackFrame *frame = (JanetStackFrame *)(fiber->data + i - JANET_FRAME_SIZE);
if (real_offset == i &&
frame->env == env &&
frame->func &&
frame->func->def->slotcount == env->length) {
env->offset = real_offset;
return 1;
}
i = frame->prevframe;
}
/* Invalid, set to empty off-stack variant. */
env->offset = 0;
env->length = 0;
env->as.values = NULL;
return 0;
} else {
return 1;
}
}
/* Detach a fiber from the env if the target fiber has stopped mutating */
void janet_env_maybe_detach(JanetFuncEnv *env) {
/* Check for detachable closure envs */
janet_env_valid(env);
if (env->offset > 0) {
JanetFiberStatus s = janet_fiber_status(env->as.fiber);
int isFinished = s == JANET_STATUS_DEAD ||
s == JANET_STATUS_ERROR ||
s == JANET_STATUS_USER0 ||
s == JANET_STATUS_USER1 ||
s == JANET_STATUS_USER2 ||
s == JANET_STATUS_USER3 ||
s == JANET_STATUS_USER4;
if (isFinished) {
janet_env_detach(env);
}
}
}
/* Create a tail frame for a function */
int janet_fiber_funcframe_tail(JanetFiber *fiber, JanetFunction *func) {
int32_t i;
int32_t nextframetop = fiber->frame + func->def->slotcount;
int32_t nextstacktop = nextframetop + JANET_FRAME_SIZE;
int32_t next_arity = fiber->stacktop - fiber->stackstart;
int32_t stacksize;
/* Check strict arity before messing with state */
if (next_arity < func->def->min_arity) return 1;
if (next_arity > func->def->max_arity) return 1;
if (fiber->capacity < nextstacktop) {
janet_fiber_setcapacity(fiber, 2 * nextstacktop);
}
Janet *stack = fiber->data + fiber->frame;
Janet *args = fiber->data + fiber->stackstart;
/* Detach old function */
if (NULL != janet_fiber_frame(fiber)->func)
janet_env_detach(janet_fiber_frame(fiber)->env);
janet_fiber_frame(fiber)->env = NULL;
/* Check varargs */
if (func->def->flags & JANET_FUNCDEF_FLAG_VARARG) {
int32_t tuplehead = fiber->stackstart + func->def->arity;
int st = func->def->flags & JANET_FUNCDEF_FLAG_STRUCTARG;
if (tuplehead >= fiber->stacktop) {
if (tuplehead >= fiber->capacity) janet_fiber_setcapacity(fiber, 2 * (tuplehead + 1));
for (i = fiber->stacktop; i < tuplehead; ++i) fiber->data[i] = janet_wrap_nil();
fiber->data[tuplehead] = st
? make_struct_n(NULL, 0)
: janet_wrap_tuple(janet_tuple_n(NULL, 0));
} else {
fiber->data[tuplehead] = st
? make_struct_n(
fiber->data + tuplehead,
fiber->stacktop - tuplehead)
: janet_wrap_tuple(janet_tuple_n(
fiber->data + tuplehead,
fiber->stacktop - tuplehead));
}
stacksize = tuplehead - fiber->stackstart + 1;
} else {
stacksize = fiber->stacktop - fiber->stackstart;
}
if (stacksize) memmove(stack, args, stacksize * sizeof(Janet));
/* Nil unset locals (Needed for functional correctness) */
for (i = fiber->frame + stacksize; i < nextframetop; ++i)
fiber->data[i] = janet_wrap_nil();
/* Set stack stuff */
fiber->stacktop = fiber->stackstart = nextstacktop;
/* Set frame stuff */
janet_fiber_frame(fiber)->func = func;
janet_fiber_frame(fiber)->pc = func->def->bytecode;
janet_fiber_frame(fiber)->flags |= JANET_STACKFRAME_TAILCALL;
/* Good return */
return 0;
}
/* Push a stack frame to a fiber for a c function */
void janet_fiber_cframe(JanetFiber *fiber, JanetCFunction cfun) {
JanetStackFrame *newframe;
int32_t oldframe = fiber->frame;
int32_t nextframe = fiber->stackstart;
int32_t nextstacktop = fiber->stacktop + JANET_FRAME_SIZE;
if (fiber->capacity < nextstacktop) {
janet_fiber_setcapacity(fiber, 2 * nextstacktop);
}
/* Set the next frame */
fiber->frame = nextframe;
fiber->stacktop = fiber->stackstart = nextstacktop;
newframe = janet_fiber_frame(fiber);
/* Set up the new frame */
newframe->prevframe = oldframe;
newframe->pc = (uint32_t *) cfun;
newframe->func = NULL;
newframe->env = NULL;
newframe->flags = 0;
}
/* Pop a stack frame from the fiber. Returns the new stack frame, or
* NULL if there are no more frames */
void janet_fiber_popframe(JanetFiber *fiber) {
JanetStackFrame *frame = janet_fiber_frame(fiber);
if (fiber->frame == 0) return;
/* Clean up the frame (detach environments) */
if (NULL != frame->func)
janet_env_detach(frame->env);
/* Shrink stack */
fiber->stacktop = fiber->stackstart = fiber->frame;
fiber->frame = frame->prevframe;
}
JanetFiberStatus janet_fiber_status(JanetFiber *f) {
return ((f)->flags & JANET_FIBER_STATUS_MASK) >> JANET_FIBER_STATUS_OFFSET;
}
JanetFiber *janet_current_fiber(void) {
return janet_vm_fiber;
}
/* CFuns */
static Janet cfun_fiber_getenv(int32_t argc, Janet *argv) {
janet_fixarity(argc, 1);
JanetFiber *fiber = janet_getfiber(argv, 0);
return fiber->env ?
janet_wrap_table(fiber->env) :
janet_wrap_nil();
}
static Janet cfun_fiber_setenv(int32_t argc, Janet *argv) {
janet_fixarity(argc, 2);
JanetFiber *fiber = janet_getfiber(argv, 0);
if (janet_checktype(argv[1], JANET_NIL)) {
fiber->env = NULL;
} else {
fiber->env = janet_gettable(argv, 1);
}
return argv[0];
}
static Janet cfun_fiber_new(int32_t argc, Janet *argv) {
janet_arity(argc, 1, 2);
JanetFunction *func = janet_getfunction(argv, 0);
JanetFiber *fiber;
if (func->def->min_arity > 1) {
janet_panicf("fiber function must accept 0 or 1 arguments");
}
fiber = janet_fiber(func, 64, func->def->min_arity, NULL);
if (argc == 2) {
int32_t i;
JanetByteView view = janet_getbytes(argv, 1);
fiber->flags = JANET_FIBER_RESUME_NO_USEVAL | JANET_FIBER_RESUME_NO_SKIP;
janet_fiber_set_status(fiber, JANET_STATUS_NEW);
for (i = 0; i < view.len; i++) {
if (view.bytes[i] >= '0' && view.bytes[i] <= '9') {
fiber->flags |= JANET_FIBER_MASK_USERN(view.bytes[i] - '0');
} else {
switch (view.bytes[i]) {
default:
janet_panicf("invalid flag %c, expected a, d, e, u, or y", view.bytes[i]);
break;
case 'a':
fiber->flags |=
JANET_FIBER_MASK_DEBUG |
JANET_FIBER_MASK_ERROR |
JANET_FIBER_MASK_USER |
JANET_FIBER_MASK_YIELD;
break;
case 't':
fiber->flags |=
JANET_FIBER_MASK_ERROR |
JANET_FIBER_MASK_USER0 |
JANET_FIBER_MASK_USER1 |
JANET_FIBER_MASK_USER2 |
JANET_FIBER_MASK_USER3 |
JANET_FIBER_MASK_USER4;
break;
case 'd':
fiber->flags |= JANET_FIBER_MASK_DEBUG;
break;
case 'e':
fiber->flags |= JANET_FIBER_MASK_ERROR;
break;
case 'u':
fiber->flags |= JANET_FIBER_MASK_USER;
break;
case 'y':
fiber->flags |= JANET_FIBER_MASK_YIELD;
break;
case 'i':
if (!janet_vm_fiber->env) {
janet_vm_fiber->env = janet_table(0);
}
fiber->env = janet_vm_fiber->env;
break;
case 'p':
if (!janet_vm_fiber->env) {
janet_vm_fiber->env = janet_table(0);
}
fiber->env = janet_table(0);
fiber->env->proto = janet_vm_fiber->env;
break;
}
}
}
}
return janet_wrap_fiber(fiber);
}
static Janet cfun_fiber_status(int32_t argc, Janet *argv) {
janet_fixarity(argc, 1);
JanetFiber *fiber = janet_getfiber(argv, 0);
uint32_t s = janet_fiber_status(fiber);
return janet_ckeywordv(janet_status_names[s]);
}
static Janet cfun_fiber_current(int32_t argc, Janet *argv) {
(void) argv;
janet_fixarity(argc, 0);
return janet_wrap_fiber(janet_vm_fiber);
}
static Janet cfun_fiber_maxstack(int32_t argc, Janet *argv) {
janet_fixarity(argc, 1);
JanetFiber *fiber = janet_getfiber(argv, 0);
return janet_wrap_integer(fiber->maxstack);
}
static Janet cfun_fiber_setmaxstack(int32_t argc, Janet *argv) {
janet_fixarity(argc, 2);
JanetFiber *fiber = janet_getfiber(argv, 0);
int32_t maxs = janet_getinteger(argv, 1);
if (maxs < 0) {
janet_panic("expected positive integer");
}
fiber->maxstack = maxs;
return argv[0];
}
static Janet cfun_fiber_can_resume(int32_t argc, Janet *argv) {
janet_fixarity(argc, 1);
JanetFiber *fiber = janet_getfiber(argv, 0);
JanetFiberStatus s = janet_fiber_status(fiber);
int isFinished = s == JANET_STATUS_DEAD ||
s == JANET_STATUS_ERROR ||
s == JANET_STATUS_USER0 ||
s == JANET_STATUS_USER1 ||
s == JANET_STATUS_USER2 ||
s == JANET_STATUS_USER3 ||
s == JANET_STATUS_USER4;
return janet_wrap_boolean(!isFinished);
}
static const JanetReg fiber_cfuns[] = {
{
"fiber/new", cfun_fiber_new,
JDOC("(fiber/new func &opt sigmask)\n\n"
"Create a new fiber with function body func. Can optionally "
"take a set of signals to block from the current parent fiber "
"when called. The mask is specified as a keyword where each character "
"is used to indicate a signal to block. The default sigmask is :y. "
"For example, \n\n"
"\t(fiber/new myfun :e123)\n\n"
"blocks error signals and user signals 1, 2 and 3. The signals are "
"as follows: \n\n"
"\ta - block all signals\n"
"\td - block debug signals\n"
"\te - block error signals\n"
"\tt - block termination signals: error + user[0-4]\n"
"\tu - block user signals\n"
"\ty - block yield signals\n"
"\t0-9 - block a specific user signal\n\n"
"The sigmask argument also can take environment flags. If any mutually "
"exclusive flags are present, the last flag takes precedence.\n\n"
"\ti - inherit the environment from the current fiber\n"
"\tp - the environment table's prototype is the current environment table")
},
{
"fiber/status", cfun_fiber_status,
JDOC("(fiber/status fib)\n\n"
"Get the status of a fiber. The status will be one of:\n\n"
"\t:dead - the fiber has finished\n"
"\t:error - the fiber has errored out\n"
"\t:debug - the fiber is suspended in debug mode\n"
"\t:pending - the fiber has been yielded\n"
"\t:user(0-9) - the fiber is suspended by a user signal\n"
"\t:alive - the fiber is currently running and cannot be resumed\n"
"\t:new - the fiber has just been created and not yet run")
},
{
"fiber/current", cfun_fiber_current,
JDOC("(fiber/current)\n\n"
"Returns the currently running fiber.")
},
{
"fiber/maxstack", cfun_fiber_maxstack,
JDOC("(fiber/maxstack fib)\n\n"
"Gets the maximum stack size in janet values allowed for a fiber. While memory for "
"the fiber's stack is not allocated up front, the fiber will not allocated more "
"than this amount and will throw a stack-overflow error if more memory is needed. ")
},
{
"fiber/setmaxstack", cfun_fiber_setmaxstack,
JDOC("(fiber/setmaxstack fib maxstack)\n\n"
"Sets the maximum stack size in janet values for a fiber. By default, the "
"maximum stack size is usually 8192.")
},
{
"fiber/getenv", cfun_fiber_getenv,
JDOC("(fiber/getenv fiber)\n\n"
"Gets the environment for a fiber. Returns nil if no such table is "
"set yet.")
},
{
"fiber/setenv", cfun_fiber_setenv,
JDOC("(fiber/setenv fiber table)\n\n"
"Sets the environment table for a fiber. Set to nil to remove the current "
"environment.")
},
{
"fiber/can-resume?", cfun_fiber_can_resume,
JDOC("(fiber/can-resume? fiber)\n\n"
"Check if a fiber is finished and cannot be resumed.")
},
{NULL, NULL, NULL}
};
/* Module entry point */
void janet_lib_fiber(JanetTable *env) {
janet_core_cfuns(env, NULL, fiber_cfuns);
}
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