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*/
59typedef 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*/
70typedef 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
89static 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*/
106void luaE_setdebt (global_State *g, l_mem debt) {
107  g->totalbytes -= (debt - g->GCdebt);
108  g->GCdebt = debt;
109}
110
111
112CallInfo *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
122void 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
133static 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
153static 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*/
165static 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*/
183static 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*/
202static 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
221static 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
233LUA_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
252void 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
262LUA_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
315LUA_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
323