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f1afc5b0b4
janet/src/core/fiber.c
Calvin Rose 292be33b9d Fix some stack overflow bugs.
2019-08-19 01:19:51 -04:00

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/*
* Copyright (c) 2019 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 <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;
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) * 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);
}
memcpy(fiber->data + fiber->stacktop, argv, argc * sizeof(Janet));
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);
}
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) {
size_t s = sizeof(Janet) * env->length;
Janet *vmem = malloc(s);
janet_vm_next_collection += (uint32_t) s;
if (NULL == vmem) {
JANET_OUT_OF_MEMORY;
}
memcpy(vmem, env->as.fiber->data + env->offset, s);
env->offset = 0;
env->as.values = vmem;
}
}
/* 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 != 0) {
janet_panic("expected nullary function in fiber constructor");
}
fiber = janet_fiber(func, 64, 0, NULL);
if (argc == 2) {
int32_t i;
JanetByteView view = janet_getbytes(argv, 1);
fiber->flags = 0;
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 '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 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"
"\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.")
},
{NULL, NULL, NULL}
};
/* Module entry point */
void janet_lib_fiber(JanetTable *env) {
janet_core_cfuns(env, NULL, fiber_cfuns);
}
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