lstate.c
(5.3.6)
/*
** $Id: lstate.c,v 2.133.1.1 2017/04/19 17:39:34 roberto Exp $
** Global State
** See Copyright Notice in lua.h
*/
#define lstate_c
#define LUA_CORE
#include "lprefix.h"
#include <stddef.h>
#include <string.h>
#include "lua.h"
#include "lapi.h"
#include "ldebug.h"
#include "ldo.h"
#include "lfunc.h"
#include "lgc.h"
#include "llex.h"
#include "lmem.h"
#include "lstate.h"
#include "lstring.h"
#include "ltable.h"
#include "ltm.h"
#if !defined(LUAI_GCPAUSE)
#define LUAI_GCPAUSE 200 /* 200% */
#endif
#if !defined(LUAI_GCMUL)
#define LUAI_GCMUL 200 /* GC runs 'twice the speed' of memory allocation */
#endif
/*
** a macro to help the creation of a unique random seed when a state is
** created; the seed is used to randomize hashes.
*/
#if !defined(luai_makeseed)
#include <time.h>
#define luai_makeseed() cast(unsigned int, time(NULL))
#endif
/*
** thread state + extra space
*/
typedef struct LX {
lu_byte extra_[LUA_EXTRASPACE];
lua_State l;
} LX;
/*
** Main thread combines a thread state and the global state
*/
typedef struct LG {
LX l;
global_State g;
} LG;
#define fromstate(L) (cast(LX *, cast(lu_byte *, (L)) - offsetof(LX, l)))
/*
** Compute an initial seed as random as possible. Rely on Address Space
** Layout Randomization (if present) to increase randomness..
*/
#define addbuff(b,p,e) \
{ size_t t = cast(size_t, e); \
memcpy(b + p, &t, sizeof(t)); p += sizeof(t); }
static unsigned int makeseed (lua_State *L) {
char buff[4 * sizeof(size_t)];
unsigned int h = luai_makeseed();
int p = 0;
addbuff(buff, p, L); /* heap variable */
addbuff(buff, p, &h); /* local variable */
addbuff(buff, p, luaO_nilobject); /* global variable */
addbuff(buff, p, &lua_newstate); /* public function */
lua_assert(p == sizeof(buff));
return luaS_hash(buff, p, h);
}
/*
** set GCdebt to a new value keeping the value (totalbytes + GCdebt)
** invariant (and avoiding underflows in 'totalbytes')
*/
void luaE_setdebt (global_State *g, l_mem debt) {
l_mem tb = gettotalbytes(g);
lua_assert(tb > 0);
if (debt < tb - MAX_LMEM)
debt = tb - MAX_LMEM; /* will make 'totalbytes == MAX_LMEM' */
g->totalbytes = tb - debt;
g->GCdebt = debt;
}
CallInfo *luaE_extendCI (lua_State *L) {
CallInfo *ci = luaM_new(L, CallInfo);
lua_assert(L->ci->next == NULL);
L->ci->next = ci;
ci->previous = L->ci;
ci->next = NULL;
L->nci++;
return ci;
}
/*
** free all CallInfo structures not in use by a thread
*/
void luaE_freeCI (lua_State *L) {
CallInfo *ci = L->ci;
CallInfo *next = ci->next;
ci->next = NULL;
while ((ci = next) != NULL) {
next = ci->next;
luaM_free(L, ci);
L->nci--;
}
}
/*
** free half of the CallInfo structures not in use by a thread
*/
void luaE_shrinkCI (lua_State *L) {
CallInfo *ci = L->ci;
CallInfo *next2; /* next's next */
/* while there are two nexts */
while (ci->next != NULL && (next2 = ci->next->next) != NULL) {
luaM_free(L, ci->next); /* free next */
L->nci--;
ci->next = next2; /* remove 'next' from the list */
next2->previous = ci;
ci = next2; /* keep next's next */
}
}
static void stack_init (lua_State *L1, lua_State *L) {
int i; CallInfo *ci;
/* initialize stack array */
L1->stack = luaM_newvector(L, BASIC_STACK_SIZE, TValue);
L1->stacksize = BASIC_STACK_SIZE;
for (i = 0; i < BASIC_STACK_SIZE; i++)
setnilvalue(L1->stack + i); /* erase new stack */
L1->top = L1->stack;
L1->stack_last = L1->stack + L1->stacksize - EXTRA_STACK;
/* initialize first ci */
ci = &L1->base_ci;
ci->next = ci->previous = NULL;
ci->callstatus = 0;
ci->func = L1->top;
setnilvalue(L1->top++); /* 'function' entry for this 'ci' */
ci->top = L1->top + LUA_MINSTACK;
L1->ci = ci;
}
static void freestack (lua_State *L) {
if (L->stack == NULL)
return; /* stack not completely built yet */
L->ci = &L->base_ci; /* free the entire 'ci' list */
luaE_freeCI(L);
lua_assert(L->nci == 0);
luaM_freearray(L, L->stack, L->stacksize); /* free stack array */
}
/*
** Create registry table and its predefined values
*/
static void init_registry (lua_State *L, global_State *g) {
TValue temp;
/* create registry */
Table *registry = luaH_new(L);
sethvalue(L, &g->l_registry, registry);
luaH_resize(L, registry, LUA_RIDX_LAST, 0);
/* registry[LUA_RIDX_MAINTHREAD] = L */
setthvalue(L, &temp, L); /* temp = L */
luaH_setint(L, registry, LUA_RIDX_MAINTHREAD, &temp);
/* registry[LUA_RIDX_GLOBALS] = table of globals */
sethvalue(L, &temp, luaH_new(L)); /* temp = new table (global table) */
luaH_setint(L, registry, LUA_RIDX_GLOBALS, &temp);
}
/*
** open parts of the state that may cause memory-allocation errors.
** ('g->version' != NULL flags that the state was completely build)
*/
static void f_luaopen (lua_State *L, void *ud) {
global_State *g = G(L);
UNUSED(ud);
stack_init(L, L); /* init stack */
init_registry(L, g);
luaS_init(L);
luaT_init(L);
luaX_init(L);
g->gcrunning = 1; /* allow gc */
g->version = lua_version(NULL);
luai_userstateopen(L);
}
/*
** preinitialize a thread with consistent values without allocating
** any memory (to avoid errors)
*/
static void preinit_thread (lua_State *L, global_State *g) {
G(L) = g;
L->stack = NULL;
L->ci = NULL;
L->nci = 0;
L->stacksize = 0;
L->twups = L; /* thread has no upvalues */
L->errorJmp = NULL;
L->nCcalls = 0;
L->hook = NULL;
L->hookmask = 0;
L->basehookcount = 0;
L->allowhook = 1;
resethookcount(L);
L->openupval = NULL;
L->nny = 1;
L->status = LUA_OK;
L->errfunc = 0;
}
static void close_state (lua_State *L) {
global_State *g = G(L);
luaF_close(L, L->stack); /* close all upvalues for this thread */
luaC_freeallobjects(L); /* collect all objects */
if (g->version) /* closing a fully built state? */
luai_userstateclose(L);
luaM_freearray(L, G(L)->strt.hash, G(L)->strt.size);
freestack(L);
lua_assert(gettotalbytes(g) == sizeof(LG));
(*g->frealloc)(g->ud, fromstate(L), sizeof(LG), 0); /* free main block */
}
LUA_API lua_State *lua_newthread (lua_State *L) {
global_State *g = G(L);
lua_State *L1;
lua_lock(L);
luaC_checkGC(L);
/* create new thread */
L1 = &cast(LX *, luaM_newobject(L, LUA_TTHREAD, sizeof(LX)))->l;
L1->marked = luaC_white(g);
L1->tt = LUA_TTHREAD;
/* link it on list 'allgc' */
L1->next = g->allgc;
g->allgc = obj2gco(L1);
/* anchor it on L stack */
setthvalue(L, L->top, L1);
api_incr_top(L);
preinit_thread(L1, g);
L1->hookmask = L->hookmask;
L1->basehookcount = L->basehookcount;
L1->hook = L->hook;
resethookcount(L1);
/* initialize L1 extra space */
memcpy(lua_getextraspace(L1), lua_getextraspace(g->mainthread),
LUA_EXTRASPACE);
luai_userstatethread(L, L1);
stack_init(L1, L); /* init stack */
lua_unlock(L);
return L1;
}
void luaE_freethread (lua_State *L, lua_State *L1) {
LX *l = fromstate(L1);
luaF_close(L1, L1->stack); /* close all upvalues for this thread */
lua_assert(L1->openupval == NULL);
luai_userstatefree(L, L1);
freestack(L1);
luaM_free(L, l);
}
LUA_API lua_State *lua_newstate (lua_Alloc f, void *ud) {
int i;
lua_State *L;
global_State *g;
LG *l = cast(LG *, (*f)(ud, NULL, LUA_TTHREAD, sizeof(LG)));
if (l == NULL) return NULL;
L = &l->l.l;
g = &l->g;
L->next = NULL;
L->tt = LUA_TTHREAD;
g->currentwhite = bitmask(WHITE0BIT);
L->marked = luaC_white(g);
preinit_thread(L, g);
g->frealloc = f;
g->ud = ud;
g->mainthread = L;
g->seed = makeseed(L);
g->gcrunning = 0; /* no GC while building state */
g->GCestimate = 0;
g->strt.size = g->strt.nuse = 0;
g->strt.hash = NULL;
setnilvalue(&g->l_registry);
g->panic = NULL;
g->version = NULL;
g->gcstate = GCSpause;
g->gckind = KGC_NORMAL;
g->allgc = g->finobj = g->tobefnz = g->fixedgc = NULL;
g->sweepgc = NULL;
g->gray = g->grayagain = NULL;
g->weak = g->ephemeron = g->allweak = NULL;
g->twups = NULL;
g->totalbytes = sizeof(LG);
g->GCdebt = 0;
g->gcfinnum = 0;
g->gcpause = LUAI_GCPAUSE;
g->gcstepmul = LUAI_GCMUL;
for (i=0; i < LUA_NUMTAGS; i++) g->mt[i] = NULL;
if (luaD_rawrunprotected(L, f_luaopen, NULL) != LUA_OK) {
/* memory allocation error: free partial state */
close_state(L);
L = NULL;
}
return L;
}
LUA_API void lua_close (lua_State *L) {
L = G(L)->mainthread; /* only the main thread can be closed */
lua_lock(L);
close_state(L);
}