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** $Id: lstate.c,v 2.133 2015/11/13 12:16:51 roberto Exp $
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** See Copyright Notice in lua.h
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#if !defined(LUAI_GCPAUSE)
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#define LUAI_GCPAUSE 200 /* 200% */
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#if !defined(LUAI_GCMUL)
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#define LUAI_GCMUL 200 /* GC runs 'twice the speed' of memory allocation */
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** a macro to help the creation of a unique random seed when a state is
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** created; the seed is used to randomize hashes.
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#if !defined(luai_makeseed)
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#define luai_makeseed() cast(unsigned int, time(NULL))
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** thread state + extra space
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lu_byte extra_[LUA_EXTRASPACE];
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** Main thread combines a thread state and the global state
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#define fromstate(L) (cast(LX *, cast(lu_byte *, (L)) - offsetof(LX, l)))
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** Compute an initial seed as random as possible. Rely on Address Space
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** Layout Randomization (if present) to increase randomness..
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#define addbuff(b,p,e) \
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{ size_t t = cast(size_t, e); \
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memcpy(b + p, &t, sizeof(t)); p += sizeof(t); }
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static unsigned int makeseed (lua_State *L) {
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char buff[4 * sizeof(size_t)];
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unsigned int h = luai_makeseed();
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addbuff(buff, p, L); /* heap variable */
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addbuff(buff, p, &h); /* local variable */
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addbuff(buff, p, luaO_nilobject); /* global variable */
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addbuff(buff, p, &lua_newstate); /* public function */
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lua_assert(p == sizeof(buff));
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return luaS_hash(buff, p, h);
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** set GCdebt to a new value keeping the value (totalbytes + GCdebt)
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** invariant (and avoiding underflows in 'totalbytes')
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void luaE_setdebt (global_State *g, l_mem debt) {
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l_mem tb = gettotalbytes(g);
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if (debt < tb - MAX_LMEM)
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debt = tb - MAX_LMEM; /* will make 'totalbytes == MAX_LMEM' */
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g->totalbytes = tb - debt;
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CallInfo *luaE_extendCI (lua_State *L) {
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CallInfo *ci = luaM_new(L, CallInfo);
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lua_assert(L->ci->next == NULL);
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ci->previous = L->ci;
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** free all CallInfo structures not in use by a thread
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void luaE_freeCI (lua_State *L) {
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CallInfo *ci = L->ci;
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CallInfo *next = ci->next;
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while ((ci = next) != NULL) {
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** free half of the CallInfo structures not in use by a thread
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void luaE_shrinkCI (lua_State *L) {
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CallInfo *ci = L->ci;
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CallInfo *next2; /* next's next */
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/* while there are two nexts */
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while (ci->next != NULL && (next2 = ci->next->next) != NULL) {
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luaM_free(L, ci->next); /* free next */
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ci->next = next2; /* remove 'next' from the list */
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next2->previous = ci;
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ci = next2; /* keep next's next */
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static void stack_init (lua_State *L1, lua_State *L) {
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/* initialize stack array */
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L1->stack = luaM_newvector(L, BASIC_STACK_SIZE, TValue);
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L1->stacksize = BASIC_STACK_SIZE;
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for (i = 0; i < BASIC_STACK_SIZE; i++)
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setnilvalue(L1->stack + i); /* erase new stack */
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L1->stack_last = L1->stack + L1->stacksize - EXTRA_STACK;
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/* initialize first ci */
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ci->next = ci->previous = NULL;
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setnilvalue(L1->top++); /* 'function' entry for this 'ci' */
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ci->top = L1->top + LUA_MINSTACK;
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static void freestack (lua_State *L) {
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if (L->stack == NULL)
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return; /* stack not completely built yet */
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L->ci = &L->base_ci; /* free the entire 'ci' list */
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lua_assert(L->nci == 0);
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luaM_freearray(L, L->stack, L->stacksize); /* free stack array */
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** Create registry table and its predefined values
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static void init_registry (lua_State *L, global_State *g) {
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/* create registry */
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Table *registry = luaH_new(L);
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sethvalue(L, &g->l_registry, registry);
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luaH_resize(L, registry, LUA_RIDX_LAST, 0);
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/* registry[LUA_RIDX_MAINTHREAD] = L */
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setthvalue(L, &temp, L); /* temp = L */
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luaH_setint(L, registry, LUA_RIDX_MAINTHREAD, &temp);
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/* registry[LUA_RIDX_GLOBALS] = table of globals */
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sethvalue(L, &temp, luaH_new(L)); /* temp = new table (global table) */
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luaH_setint(L, registry, LUA_RIDX_GLOBALS, &temp);
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** open parts of the state that may cause memory-allocation errors.
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** ('g->version' != NULL flags that the state was completely build)
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static void f_luaopen (lua_State *L, void *ud) {
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global_State *g = G(L);
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stack_init(L, L); /* init stack */
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g->gcrunning = 1; /* allow gc */
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g->version = lua_version(NULL);
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luai_userstateopen(L);
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** preinitialize a thread with consistent values without allocating
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** any memory (to avoid errors)
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static void preinit_thread (lua_State *L, global_State *g) {
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L->twups = L; /* thread has no upvalues */
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L->basehookcount = 0;
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static void close_state (lua_State *L) {
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global_State *g = G(L);
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luaF_close(L, L->stack); /* close all upvalues for this thread */
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luaC_freeallobjects(L); /* collect all objects */
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if (g->version) /* closing a fully built state? */
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luai_userstateclose(L);
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luaM_freearray(L, G(L)->strt.hash, G(L)->strt.size);
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lua_assert(gettotalbytes(g) == sizeof(LG));
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(*g->frealloc)(g->ud, fromstate(L), sizeof(LG), 0); /* free main block */
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LUA_API lua_State *lua_newthread (lua_State *L) {
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global_State *g = G(L);
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/* create new thread */
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L1 = &cast(LX *, luaM_newobject(L, LUA_TTHREAD, sizeof(LX)))->l;
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L1->marked = luaC_white(g);
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L1->tt = LUA_TTHREAD;
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/* link it on list 'allgc' */
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g->allgc = obj2gco(L1);
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/* anchor it on L stack */
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setthvalue(L, L->top, L1);
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preinit_thread(L1, g);
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L1->hookmask = L->hookmask;
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L1->basehookcount = L->basehookcount;
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/* initialize L1 extra space */
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memcpy(lua_getextraspace(L1), lua_getextraspace(g->mainthread),
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luai_userstatethread(L, L1);
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stack_init(L1, L); /* init stack */
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void luaE_freethread (lua_State *L, lua_State *L1) {
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LX *l = fromstate(L1);
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luaF_close(L1, L1->stack); /* close all upvalues for this thread */
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lua_assert(L1->openupval == NULL);
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luai_userstatefree(L, L1);
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LUA_API lua_State *lua_newstate (lua_Alloc f, void *ud) {
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LG *l = cast(LG *, (*f)(ud, NULL, LUA_TTHREAD, sizeof(LG)));
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if (l == NULL) return NULL;
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g->currentwhite = bitmask(WHITE0BIT);
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L->marked = luaC_white(g);
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preinit_thread(L, g);
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g->seed = makeseed(L);
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g->gcrunning = 0; /* no GC while building state */
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g->strt.size = g->strt.nuse = 0;
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setnilvalue(&g->l_registry);
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g->gcstate = GCSpause;
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g->gckind = KGC_NORMAL;
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g->allgc = g->finobj = g->tobefnz = g->fixedgc = NULL;
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g->gray = g->grayagain = NULL;
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g->weak = g->ephemeron = g->allweak = NULL;
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g->totalbytes = sizeof(LG);
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g->gcpause = LUAI_GCPAUSE;
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g->gcstepmul = LUAI_GCMUL;
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for (i=0; i < LUA_NUMTAGS; i++) g->mt[i] = NULL;
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if (luaD_rawrunprotected(L, f_luaopen, NULL) != LUA_OK) {
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/* memory allocation error: free partial state */
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LUA_API void lua_close (lua_State *L) {
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L = G(L)->mainthread; /* only the main thread can be closed */