liblua/lstate.c

   1 /*
   2 ** $Id: lstate.c,v 2.99 2012/10/02 17:40:53 roberto Exp $
   3 ** Global State
   4 ** See Copyright Notice in lua.h
   5 */
   6
   7
   8 #include <stddef.h>
   9 #include <string.h>
  10
  11 #define lstate_c
  12 #define LUA_CORE
  13
  14 #include "lua.h"
  15
  16 #include "lapi.h"
  17 #include "ldebug.h"
  18 #include "ldo.h"
  19 #include "lfunc.h"
  20 #include "lgc.h"
  21 #include "llex.h"
  22 #include "lmem.h"
  23 #include "lstate.h"
  24 #include "lstring.h"
  25 #include "ltable.h"
  26 #include "ltm.h"
  27
  28
  29 #if !defined(LUAI_GCPAUSE)
  30 #define LUAI_GCPAUSE    200  /* 200% */
  31 #endif
  32
  33 #if !defined(LUAI_GCMAJOR)
  34 #define LUAI_GCMAJOR    200  /* 200% */
  35 #endif
  36
  37 #if !defined(LUAI_GCMUL)
  38 #define LUAI_GCMUL      200 /* GC runs 'twice the speed' of memory allocation */
  39 #endif
  40
  41
  42 #define MEMERRMSG       "not enough memory"
  43
  44
  45 /*
  46 ** a macro to help the creation of a unique random seed when a state is
  47 ** created; the seed is used to randomize hashes.
  48 */
  49 #if !defined(luai_makeseed)
  50 #include <time.h>
  51 #define luai_makeseed()         cast(unsigned int, time(NULL))
  52 #endif
  53
  54
  55
  56 /*
  57 ** thread state + extra space
  58 */
  59 typedef struct LX {
  60 #if defined(LUAI_EXTRASPACE)
  61   char buff[LUAI_EXTRASPACE];
  62 #endif
  63   lua_State l;
  64 } LX;
  65
  66
  67 /*
  68 ** Main thread combines a thread state and the global state
  69 */
  70 typedef struct LG {
  71   LX l;
  72   global_State g;
  73 } LG;
  74
  75
  76
  77 #define fromstate(L)    (cast(LX *, cast(lu_byte *, (L)) - offsetof(LX, l)))
  78
  79
  80 /*
  81 ** Compute an initial seed as random as possible. In ANSI, rely on
  82 ** Address Space Layout Randomization (if present) to increase
  83 ** randomness..
  84 */
  85 #define addbuff(b,p,e) \
  86   { size_t t = cast(size_t, e); \
  87     memcpy(buff + p, &t, sizeof(t)); p += sizeof(t); }
  88
  89 static unsigned int makeseed (lua_State *L) {
  90   char buff[4 * sizeof(size_t)];
  91   unsigned int h = luai_makeseed();
  92   int p = 0;
  93   addbuff(buff, p, L);  /* heap variable */
  94   addbuff(buff, p, &h);  /* local variable */
  95   addbuff(buff, p, luaO_nilobject);  /* global variable */
  96   addbuff(buff, p, &lua_newstate);  /* public function */
  97   lua_assert(p == sizeof(buff));
  98   return luaS_hash(buff, p, h);
  99 }
 100
 101
 102 /*
 103 ** set GCdebt to a new value keeping the value (totalbytes + GCdebt)
 104 ** invariant
 105 */
 106 void luaE_setdebt (global_State *g, l_mem debt) {
 107   g->totalbytes -= (debt - g->GCdebt);
 108   g->GCdebt = debt;
 109 }
 110
 111
 112 CallInfo *luaE_extendCI (lua_State *L) {
 113   CallInfo *ci = luaM_new(L, CallInfo);
 114   lua_assert(L->ci->next == NULL);
 115   L->ci->next = ci;
 116   ci->previous = L->ci;
 117   ci->next = NULL;
 118   return ci;
 119 }
 120
 121
 122 void luaE_freeCI (lua_State *L) {
 123   CallInfo *ci = L->ci;
 124   CallInfo *next = ci->next;
 125   ci->next = NULL;
 126   while ((ci = next) != NULL) {
 127     next = ci->next;
 128     luaM_free(L, ci);
 129   }
 130 }
 131
 132
 133 static void stack_init (lua_State *L1, lua_State *L) {
 134   int i; CallInfo *ci;
 135   /* initialize stack array */
 136   L1->stack = luaM_newvector(L, BASIC_STACK_SIZE, TValue);
 137   L1->stacksize = BASIC_STACK_SIZE;
 138   for (i = 0; i < BASIC_STACK_SIZE; i++)
 139     setnilvalue(L1->stack + i);  /* erase new stack */
 140   L1->top = L1->stack;
 141   L1->stack_last = L1->stack + L1->stacksize - EXTRA_STACK;
 142   /* initialize first ci */
 143   ci = &L1->base_ci;
 144   ci->next = ci->previous = NULL;
 145   ci->callstatus = 0;
 146   ci->func = L1->top;
 147   setnilvalue(L1->top++);  /* 'function' entry for this 'ci' */
 148   ci->top = L1->top + LUA_MINSTACK;
 149   L1->ci = ci;
 150 }
 151
 152
 153 static void freestack (lua_State *L) {
 154   if (L->stack == NULL)
 155     return;  /* stack not completely built yet */
 156   L->ci = &L->base_ci;  /* free the entire 'ci' list */
 157   luaE_freeCI(L);
 158   luaM_freearray(L, L->stack, L->stacksize);  /* free stack array */
 159 }
 160
 161
 162 /*
 163 ** Create registry table and its predefined values
 164 */
 165 static void init_registry (lua_State *L, global_State *g) {
 166   TValue mt;
 167   /* create registry */
 168   Table *registry = luaH_new(L);
 169   sethvalue(L, &g->l_registry, registry);
 170   luaH_resize(L, registry, LUA_RIDX_LAST, 0);
 171   /* registry[LUA_RIDX_MAINTHREAD] = L */
 172   setthvalue(L, &mt, L);
 173   luaH_setint(L, registry, LUA_RIDX_MAINTHREAD, &mt);
 174   /* registry[LUA_RIDX_GLOBALS] = table of globals */
 175   sethvalue(L, &mt, luaH_new(L));
 176   luaH_setint(L, registry, LUA_RIDX_GLOBALS, &mt);
 177 }
 178
 179
 180 /*
 181 ** open parts of the state that may cause memory-allocation errors
 182 */
 183 static void f_luaopen (lua_State *L, void *ud) {
 184   global_State *g = G(L);
 185   UNUSED(ud);
 186   stack_init(L, L);  /* init stack */
 187   init_registry(L, g);
 188   luaS_resize(L, MINSTRTABSIZE);  /* initial size of string table */
 189   luaT_init(L);
 190   luaX_init(L);
 191   /* pre-create memory-error message */
 192   g->memerrmsg = luaS_newliteral(L, MEMERRMSG);
 193   luaS_fix(g->memerrmsg);  /* it should never be collected */
 194   g->gcrunning = 1;  /* allow gc */
 195 }
 196
 197
 198 /*
 199 ** preinitialize a state with consistent values without allocating
 200 ** any memory (to avoid errors)
 201 */
 202 static void preinit_state (lua_State *L, global_State *g) {
 203   G(L) = g;
 204   L->stack = NULL;
 205   L->ci = NULL;
 206   L->stacksize = 0;
 207   L->errorJmp = NULL;
 208   L->nCcalls = 0;
 209   L->hook = NULL;
 210   L->hookmask = 0;
 211   L->basehookcount = 0;
 212   L->allowhook = 1;
 213   resethookcount(L);
 214   L->openupval = NULL;
 215   L->nny = 1;
 216   L->status = LUA_OK;
 217   L->errfunc = 0;
 218 }
 219
 220
 221 static void close_state (lua_State *L) {
 222   global_State *g = G(L);
 223   luaF_close(L, L->stack);  /* close all upvalues for this thread */
 224   luaC_freeallobjects(L);  /* collect all objects */
 225   luaM_freearray(L, G(L)->strt.hash, G(L)->strt.size);
 226   luaZ_freebuffer(L, &g->buff);
 227   freestack(L);
 228   lua_assert(gettotalbytes(g) == sizeof(LG));
 229   (*g->frealloc)(g->ud, fromstate(L), sizeof(LG), 0);  /* free main block */
 230 }
 231
 232
 233 LUA_API lua_State *lua_newthread (lua_State *L) {
 234   lua_State *L1;
 235   lua_lock(L);
 236   luaC_checkGC(L);
 237   L1 = &luaC_newobj(L, LUA_TTHREAD, sizeof(LX), NULL, offsetof(LX, l))->th;
 238   setthvalue(L, L->top, L1);
 239   api_incr_top(L);
 240   preinit_state(L1, G(L));
 241   L1->hookmask = L->hookmask;
 242   L1->basehookcount = L->basehookcount;
 243   L1->hook = L->hook;
 244   resethookcount(L1);
 245   luai_userstatethread(L, L1);
 246   stack_init(L1, L);  /* init stack */
 247   lua_unlock(L);
 248   return L1;
 249 }
 250
 251
 252 void luaE_freethread (lua_State *L, lua_State *L1) {
 253   LX *l = fromstate(L1);
 254   luaF_close(L1, L1->stack);  /* close all upvalues for this thread */
 255   lua_assert(L1->openupval == NULL);
 256   luai_userstatefree(L, L1);
 257   freestack(L1);
 258   luaM_free(L, l);
 259 }
 260
 261
 262 LUA_API lua_State *lua_newstate (lua_Alloc f, void *ud) {
 263   int i;
 264   lua_State *L;
 265   global_State *g;
 266   LG *l = cast(LG *, (*f)(ud, NULL, LUA_TTHREAD, sizeof(LG)));
 267   if (l == NULL) return NULL;
 268   L = &l->l.l;
 269   g = &l->g;
 270   L->next = NULL;
 271   L->tt = LUA_TTHREAD;
 272   g->currentwhite = bit2mask(WHITE0BIT, FIXEDBIT);
 273   L->marked = luaC_white(g);
 274   g->gckind = KGC_NORMAL;
 275   preinit_state(L, g);
 276   g->frealloc = f;
 277   g->ud = ud;
 278   g->mainthread = L;
 279   g->seed = makeseed(L);
 280   g->uvhead.u.l.prev = &g->uvhead;
 281   g->uvhead.u.l.next = &g->uvhead;
 282   g->gcrunning = 0;  /* no GC while building state */
 283   g->GCestimate = 0;
 284   g->strt.size = 0;
 285   g->strt.nuse = 0;
 286   g->strt.hash = NULL;
 287   setnilvalue(&g->l_registry);
 288   luaZ_initbuffer(L, &g->buff);
 289   g->panic = NULL;
 290   g->version = lua_version(NULL);
 291   g->gcstate = GCSpause;
 292   g->allgc = NULL;
 293   g->finobj = NULL;
 294   g->tobefnz = NULL;
 295   g->sweepgc = g->sweepfin = NULL;
 296   g->gray = g->grayagain = NULL;
 297   g->weak = g->ephemeron = g->allweak = NULL;
 298   g->totalbytes = sizeof(LG);
 299   g->GCdebt = 0;
 300   g->gcpause = LUAI_GCPAUSE;
 301   g->gcmajorinc = LUAI_GCMAJOR;
 302   g->gcstepmul = LUAI_GCMUL;
 303   for (i=0; i < LUA_NUMTAGS; i++) g->mt[i] = NULL;
 304   if (luaD_rawrunprotected(L, f_luaopen, NULL) != LUA_OK) {
 305     /* memory allocation error: free partial state */
 306     close_state(L);
 307     L = NULL;
 308   }
 309   else
 310     luai_userstateopen(L);
 311   return L;
 312 }
 313
 314
 315 LUA_API void lua_close (lua_State *L) {
 316   L = G(L)->mainthread;  /* only the main thread can be closed */
 317   lua_lock(L);
 318   luai_userstateclose(L);
 319   close_state(L);
 320 }
 321
 322