lua/lcorolib.c at master · lua/lua

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roberto-ieru Bug: stack overflow with nesting of coroutine.close

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Oct 25, 2022

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	/*
	** $Id: lcorolib.c $
	** Coroutine Library
	** See Copyright Notice in lua.h
	*/

	#define lcorolib_c
	#define LUA_LIB

	#include "lprefix.h"


	#include <stdlib.h>

	#include "lua.h"

	#include "lauxlib.h"
	#include "lualib.h"


	static lua_State getco (lua_State L) {
	lua_State *co = lua_tothread(L, 1);
	luaL_argexpected(L, co, 1, "thread");
	return co;
	}


	/*
	** Resumes a coroutine. Returns the number of results for non-error
	** cases or -1 for errors.
	*/
	static int auxresume (lua_State L, lua_State co, int narg) {
	int status, nres;
	if (l_unlikely(!lua_checkstack(co, narg))) {
	lua_pushliteral(L, "too many arguments to resume");
	return -1; /* error flag */
	}
	lua_xmove(L, co, narg);
	status = lua_resume(co, L, narg, &nres);
	if (l_likely(status == LUA_OK \|\| status == LUA_YIELD)) {
	if (l_unlikely(!lua_checkstack(L, nres + 1))) {
	lua_pop(co, nres); /* remove results anyway */
	lua_pushliteral(L, "too many results to resume");
	return -1; /* error flag */
	}
	lua_xmove(co, L, nres); /* move yielded values */
	return nres;
	}
	else {
	lua_xmove(co, L, 1); /* move error message */
	return -1; /* error flag */
	}
	}


	static int luaB_coresume (lua_State *L) {
	lua_State *co = getco(L);
	int r;
	r = auxresume(L, co, lua_gettop(L) - 1);
	if (l_unlikely(r < 0)) {
	lua_pushboolean(L, 0);
	lua_insert(L, -2);
	return 2; /* return false + error message */
	}
	else {
	lua_pushboolean(L, 1);
	lua_insert(L, -(r + 1));
	return r + 1; /* return true + 'resume' returns */
	}
	}


	static int luaB_auxwrap (lua_State *L) {
	lua_State *co = lua_tothread(L, lua_upvalueindex(1));
	int r = auxresume(L, co, lua_gettop(L));
	if (l_unlikely(r < 0)) { /* error? */
	int stat = lua_status(co);
	if (stat != LUA_OK && stat != LUA_YIELD) { /* error in the coroutine? */
	stat = lua_resetthread(co, L); /* close its tbc variables */
	lua_assert(stat != LUA_OK);
	lua_xmove(co, L, 1); /* move error message to the caller */
	}
	if (stat != LUA_ERRMEM && /* not a memory error and ... */
	lua_type(L, -1) == LUA_TSTRING) { /* ... error object is a string? */
	luaL_where(L, 1); /* add extra info, if available */
	lua_insert(L, -2);
	lua_concat(L, 2);
	}
	return lua_error(L); /* propagate error */
	}
	return r;
	}


	static int luaB_cocreate (lua_State *L) {
	lua_State *NL;
	luaL_checktype(L, 1, LUA_TFUNCTION);
	NL = lua_newthread(L);
	lua_pushvalue(L, 1); /* move function to top */
	lua_xmove(L, NL, 1); /* move function from L to NL */
	return 1;
	}


	static int luaB_cowrap (lua_State *L) {
	luaB_cocreate(L);
	lua_pushcclosure(L, luaB_auxwrap, 1);
	return 1;
	}


	static int luaB_yield (lua_State *L) {
	return lua_yield(L, lua_gettop(L));
	}


	#define COS_RUN 0
	#define COS_DEAD 1
	#define COS_YIELD 2
	#define COS_NORM 3


	static const char *const statname[] =
	{"running", "dead", "suspended", "normal"};


	static int auxstatus (lua_State L, lua_State co) {
	if (L == co) return COS_RUN;
	else {
	switch (lua_status(co)) {
	case LUA_YIELD:
	return COS_YIELD;
	case LUA_OK: {
	lua_Debug ar;
	if (lua_getstack(co, 0, &ar)) /* does it have frames? */
	return COS_NORM; /* it is running */
	else if (lua_gettop(co) == 0)
	return COS_DEAD;
	else
	return COS_YIELD; /* initial state */
	}
	default: /* some error occurred */
	return COS_DEAD;
	}
	}
	}


	static int luaB_costatus (lua_State *L) {
	lua_State *co = getco(L);
	lua_pushstring(L, statname[auxstatus(L, co)]);
	return 1;
	}


	static int luaB_yieldable (lua_State *L) {
	lua_State *co = lua_isnone(L, 1) ? L : getco(L);
	lua_pushboolean(L, lua_isyieldable(co));
	return 1;
	}


	static int luaB_corunning (lua_State *L) {
	int ismain = lua_pushthread(L);
	lua_pushboolean(L, ismain);
	return 2;
	}


	static int luaB_close (lua_State *L) {
	lua_State *co = getco(L);
	int status = auxstatus(L, co);
	switch (status) {
	case COS_DEAD: case COS_YIELD: {
	status = lua_resetthread(co, L);
	if (status == LUA_OK) {
	lua_pushboolean(L, 1);
	return 1;
	}
	else {
	lua_pushboolean(L, 0);
	lua_xmove(co, L, 1); /* move error message */
	return 2;
	}
	}
	default: /* normal or running coroutine */
	return luaL_error(L, "cannot close a %s coroutine", statname[status]);
	}
	}


	static const luaL_Reg co_funcs[] = {
	{"create", luaB_cocreate},
	{"resume", luaB_coresume},
	{"running", luaB_corunning},
	{"status", luaB_costatus},
	{"wrap", luaB_cowrap},
	{"yield", luaB_yield},
	{"isyieldable", luaB_yieldable},
	{"close", luaB_close},
	{NULL, NULL}
	};



	LUAMOD_API int luaopen_coroutine (lua_State *L) {
	luaL_newlib(L, co_funcs);
	return 1;
	}