1 /*
2 ** $Id: lstate.c $
3 ** Global State
4 ** See Copyright Notice in lua.h
5 */
6
7 #define lstate_c
8 #define LUA_CORE
9
10 #include "lprefix.h"
11
12
13 #include <stddef.h>
14 #include <string.h>
15
16 #include "lua.h"
17
18 #include "lapi.h"
19 #include "ldebug.h"
20 #include "ldo.h"
21 #include "lfunc.h"
22 #include "lgc.h"
23 #include "llex.h"
24 #include "lmem.h"
25 #include "lstate.h"
26 #include "lstring.h"
27 #include "ltable.h"
28 #include "ltm.h"
29
30
31
32 /*
33 ** thread state + extra space
34 */
35 typedef struct LX {
36 lu_byte extra_[LUA_EXTRASPACE];
37 lua_State l;
38 } LX;
39
40
41 /*
42 ** Main thread combines a thread state and the global state
43 */
44 typedef struct LG {
45 LX l;
46 global_State g;
47 } LG;
48
49
50
51 #define fromstate(L) (cast(LX *, cast(lu_byte *, (L)) - offsetof(LX, l)))
52
53
54 /*
55 ** A macro to create a "random" seed when a state is created;
56 ** the seed is used to randomize string hashes.
57 */
58 #if !defined(luai_makeseed)
59
60 #include <time.h>
61
62 /*
63 ** Compute an initial seed with some level of randomness.
64 ** Rely on Address Space Layout Randomization (if present) and
65 ** current time.
66 */
67 #define addbuff(b,p,e) \
68 { size_t t = cast_sizet(e); \
69 memcpy(b + p, &t, sizeof(t)); p += sizeof(t); }
70
luai_makeseed(lua_State * L)71 static unsigned int luai_makeseed (lua_State *L) {
72 char buff[3 * sizeof(size_t)];
73 unsigned int h = cast_uint(time(NULL));
74 int p = 0;
75 addbuff(buff, p, L); /* heap variable */
76 addbuff(buff, p, &h); /* local variable */
77 addbuff(buff, p, &lua_newstate); /* public function */
78 lua_assert(p == sizeof(buff));
79 return luaS_hash(buff, p, h, 1);
80 }
81
82 #endif
83
84
85 /*
86 ** set GCdebt to a new value keeping the value (totalbytes + GCdebt)
87 ** invariant (and avoiding underflows in 'totalbytes')
88 */
luaE_setdebt(global_State * g,l_mem debt)89 void luaE_setdebt (global_State *g, l_mem debt) {
90 l_mem tb = gettotalbytes(g);
91 lua_assert(tb > 0);
92 if (debt < tb - MAX_LMEM)
93 debt = tb - MAX_LMEM; /* will make 'totalbytes == MAX_LMEM' */
94 g->totalbytes = tb - debt;
95 g->GCdebt = debt;
96 }
97
98
lua_setcstacklimit(lua_State * L,unsigned int limit)99 LUA_API int lua_setcstacklimit (lua_State *L, unsigned int limit) {
100 global_State *g = G(L);
101 int ccalls;
102 luaE_freeCI(L); /* release unused CIs */
103 ccalls = getCcalls(L);
104 if (limit >= 40000)
105 return 0; /* out of bounds */
106 limit += CSTACKERR;
107 if (L != g-> mainthread)
108 return 0; /* only main thread can change the C stack */
109 else if (ccalls <= CSTACKERR)
110 return 0; /* handling overflow */
111 else {
112 int diff = limit - g->Cstacklimit;
113 if (ccalls + diff <= CSTACKERR)
114 return 0; /* new limit would cause an overflow */
115 g->Cstacklimit = limit; /* set new limit */
116 L->nCcalls += diff; /* correct 'nCcalls' */
117 return limit - diff - CSTACKERR; /* success; return previous limit */
118 }
119 }
120
121
122 /*
123 ** Decrement count of "C calls" and check for overflows. In case of
124 ** a stack overflow, check appropriate error ("regular" overflow or
125 ** overflow while handling stack overflow). If 'nCcalls' is smaller
126 ** than CSTACKERR but larger than CSTACKMARK, it means it has just
127 ** entered the "overflow zone", so the function raises an overflow
128 ** error. If 'nCcalls' is smaller than CSTACKMARK (which means it is
129 ** already handling an overflow) but larger than CSTACKERRMARK, does
130 ** not report an error (to allow message handling to work). Otherwise,
131 ** report a stack overflow while handling a stack overflow (probably
132 ** caused by a repeating error in the message handling function).
133 */
134
luaE_enterCcall(lua_State * L)135 void luaE_enterCcall (lua_State *L) {
136 int ncalls = getCcalls(L);
137 L->nCcalls--;
138 if (ncalls <= CSTACKERR) { /* possible overflow? */
139 luaE_freeCI(L); /* release unused CIs */
140 ncalls = getCcalls(L); /* update call count */
141 if (ncalls <= CSTACKERR) { /* still overflow? */
142 if (ncalls <= CSTACKERRMARK) /* below error-handling zone? */
143 luaD_throw(L, LUA_ERRERR); /* error while handling stack error */
144 else if (ncalls >= CSTACKMARK) {
145 /* not in error-handling zone; raise the error now */
146 L->nCcalls = (CSTACKMARK - 1); /* enter error-handling zone */
147 luaG_runerror(L, "C stack overflow");
148 }
149 /* else stack is in the error-handling zone;
150 allow message handler to work */
151 }
152 }
153 }
154
155
luaE_extendCI(lua_State * L)156 CallInfo *luaE_extendCI (lua_State *L) {
157 CallInfo *ci;
158 lua_assert(L->ci->next == NULL);
159 luaE_enterCcall(L);
160 ci = luaM_new(L, CallInfo);
161 lua_assert(L->ci->next == NULL);
162 L->ci->next = ci;
163 ci->previous = L->ci;
164 ci->next = NULL;
165 ci->u.l.trap = 0;
166 L->nci++;
167 return ci;
168 }
169
170
171 /*
172 ** free all CallInfo structures not in use by a thread
173 */
luaE_freeCI(lua_State * L)174 void luaE_freeCI (lua_State *L) {
175 CallInfo *ci = L->ci;
176 CallInfo *next = ci->next;
177 ci->next = NULL;
178 L->nCcalls += L->nci; /* add removed elements back to 'nCcalls' */
179 while ((ci = next) != NULL) {
180 next = ci->next;
181 luaM_free(L, ci);
182 L->nci--;
183 }
184 L->nCcalls -= L->nci; /* adjust result */
185 }
186
187
188 /*
189 ** free half of the CallInfo structures not in use by a thread,
190 ** keeping the first one.
191 */
luaE_shrinkCI(lua_State * L)192 void luaE_shrinkCI (lua_State *L) {
193 CallInfo *ci = L->ci->next; /* first free CallInfo */
194 CallInfo *next;
195 if (ci == NULL)
196 return; /* no extra elements */
197 L->nCcalls += L->nci; /* add removed elements back to 'nCcalls' */
198 while ((next = ci->next) != NULL) { /* two extra elements? */
199 CallInfo *next2 = next->next; /* next's next */
200 ci->next = next2; /* remove next from the list */
201 L->nci--;
202 luaM_free(L, next); /* free next */
203 if (next2 == NULL)
204 break; /* no more elements */
205 else {
206 next2->previous = ci;
207 ci = next2; /* continue */
208 }
209 }
210 L->nCcalls -= L->nci; /* adjust result */
211 }
212
213
stack_init(lua_State * L1,lua_State * L)214 static void stack_init (lua_State *L1, lua_State *L) {
215 int i; CallInfo *ci;
216 /* initialize stack array */
217 L1->stack = luaM_newvector(L, BASIC_STACK_SIZE, StackValue);
218 L1->stacksize = BASIC_STACK_SIZE;
219 for (i = 0; i < BASIC_STACK_SIZE; i++)
220 setnilvalue(s2v(L1->stack + i)); /* erase new stack */
221 L1->top = L1->stack;
222 L1->stack_last = L1->stack + L1->stacksize - EXTRA_STACK;
223 /* initialize first ci */
224 ci = &L1->base_ci;
225 ci->next = ci->previous = NULL;
226 ci->callstatus = CIST_C;
227 ci->func = L1->top;
228 ci->u.c.k = NULL;
229 ci->nresults = 0;
230 setnilvalue(s2v(L1->top)); /* 'function' entry for this 'ci' */
231 L1->top++;
232 ci->top = L1->top + LUA_MINSTACK;
233 L1->ci = ci;
234 }
235
236
freestack(lua_State * L)237 static void freestack (lua_State *L) {
238 if (L->stack == NULL)
239 return; /* stack not completely built yet */
240 L->ci = &L->base_ci; /* free the entire 'ci' list */
241 luaE_freeCI(L);
242 lua_assert(L->nci == 0);
243 luaM_freearray(L, L->stack, L->stacksize); /* free stack array */
244 }
245
246
247 /*
248 ** Create registry table and its predefined values
249 */
init_registry(lua_State * L,global_State * g)250 static void init_registry (lua_State *L, global_State *g) {
251 TValue temp;
252 /* create registry */
253 Table *registry = luaH_new(L);
254 sethvalue(L, &g->l_registry, registry);
255 luaH_resize(L, registry, LUA_RIDX_LAST, 0);
256 /* registry[LUA_RIDX_MAINTHREAD] = L */
257 setthvalue(L, &temp, L); /* temp = L */
258 luaH_setint(L, registry, LUA_RIDX_MAINTHREAD, &temp);
259 /* registry[LUA_RIDX_GLOBALS] = table of globals */
260 sethvalue(L, &temp, luaH_new(L)); /* temp = new table (global table) */
261 luaH_setint(L, registry, LUA_RIDX_GLOBALS, &temp);
262 }
263
264
265 /*
266 ** open parts of the state that may cause memory-allocation errors.
267 ** ('g->nilvalue' being a nil value flags that the state was completely
268 ** build.)
269 */
f_luaopen(lua_State * L,void * ud)270 static void f_luaopen (lua_State *L, void *ud) {
271 global_State *g = G(L);
272 UNUSED(ud);
273 stack_init(L, L); /* init stack */
274 init_registry(L, g);
275 luaS_init(L);
276 luaT_init(L);
277 luaX_init(L);
278 g->gcrunning = 1; /* allow gc */
279 setnilvalue(&g->nilvalue);
280 luai_userstateopen(L);
281 }
282
283
284 /*
285 ** preinitialize a thread with consistent values without allocating
286 ** any memory (to avoid errors)
287 */
preinit_thread(lua_State * L,global_State * g)288 static void preinit_thread (lua_State *L, global_State *g) {
289 G(L) = g;
290 L->stack = NULL;
291 L->ci = NULL;
292 L->nci = 0;
293 L->stacksize = 0;
294 L->twups = L; /* thread has no upvalues */
295 L->errorJmp = NULL;
296 L->hook = NULL;
297 L->hookmask = 0;
298 L->basehookcount = 0;
299 L->allowhook = 1;
300 resethookcount(L);
301 L->openupval = NULL;
302 L->status = LUA_OK;
303 L->errfunc = 0;
304 L->oldpc = 0;
305 }
306
307
close_state(lua_State * L)308 static void close_state (lua_State *L) {
309 global_State *g = G(L);
310 luaF_close(L, L->stack, CLOSEPROTECT); /* close all upvalues */
311 luaC_freeallobjects(L); /* collect all objects */
312 if (ttisnil(&g->nilvalue)) /* closing a fully built state? */
313 luai_userstateclose(L);
314 luaM_freearray(L, G(L)->strt.hash, G(L)->strt.size);
315 freestack(L);
316 lua_assert(gettotalbytes(g) == sizeof(LG));
317 (*g->frealloc)(g->ud, fromstate(L), sizeof(LG), 0); /* free main block */
318 }
319
320
lua_newthread(lua_State * L)321 LUA_API lua_State *lua_newthread (lua_State *L) {
322 global_State *g;
323 lua_State *L1;
324 lua_lock(L);
325 g = G(L);
326 luaC_checkGC(L);
327 /* create new thread */
328 L1 = &cast(LX *, luaM_newobject(L, LUA_TTHREAD, sizeof(LX)))->l;
329 L1->marked = luaC_white(g);
330 L1->tt = LUA_VTHREAD;
331 /* link it on list 'allgc' */
332 L1->next = g->allgc;
333 g->allgc = obj2gco(L1);
334 /* anchor it on L stack */
335 setthvalue2s(L, L->top, L1);
336 api_incr_top(L);
337 preinit_thread(L1, g);
338 L1->nCcalls = getCcalls(L);
339 L1->hookmask = L->hookmask;
340 L1->basehookcount = L->basehookcount;
341 L1->hook = L->hook;
342 resethookcount(L1);
343 /* initialize L1 extra space */
344 memcpy(lua_getextraspace(L1), lua_getextraspace(g->mainthread),
345 LUA_EXTRASPACE);
346 luai_userstatethread(L, L1);
347 stack_init(L1, L); /* init stack */
348 lua_unlock(L);
349 return L1;
350 }
351
352
luaE_freethread(lua_State * L,lua_State * L1)353 void luaE_freethread (lua_State *L, lua_State *L1) {
354 LX *l = fromstate(L1);
355 luaF_close(L1, L1->stack, NOCLOSINGMETH); /* close all upvalues */
356 lua_assert(L1->openupval == NULL);
357 luai_userstatefree(L, L1);
358 freestack(L1);
359 luaM_free(L, l);
360 }
361
362
lua_resetthread(lua_State * L)363 int lua_resetthread (lua_State *L) {
364 CallInfo *ci;
365 int status;
366 lua_lock(L);
367 L->ci = ci = &L->base_ci; /* unwind CallInfo list */
368 setnilvalue(s2v(L->stack)); /* 'function' entry for basic 'ci' */
369 ci->func = L->stack;
370 ci->callstatus = CIST_C;
371 status = luaF_close(L, L->stack, CLOSEPROTECT);
372 if (status != CLOSEPROTECT) /* real errors? */
373 luaD_seterrorobj(L, status, L->stack + 1);
374 else {
375 status = LUA_OK;
376 L->top = L->stack + 1;
377 }
378 ci->top = L->top + LUA_MINSTACK;
379 L->status = status;
380 lua_unlock(L);
381 return status;
382 }
383
384
lua_newstate(lua_Alloc f,void * ud)385 LUA_API lua_State *lua_newstate (lua_Alloc f, void *ud) {
386 int i;
387 lua_State *L;
388 global_State *g;
389 LG *l = cast(LG *, (*f)(ud, NULL, LUA_TTHREAD, sizeof(LG)));
390 if (l == NULL) return NULL;
391 L = &l->l.l;
392 g = &l->g;
393 L->tt = LUA_VTHREAD;
394 g->currentwhite = bitmask(WHITE0BIT);
395 L->marked = luaC_white(g);
396 preinit_thread(L, g);
397 g->allgc = obj2gco(L); /* by now, only object is the main thread */
398 L->next = NULL;
399 g->Cstacklimit = L->nCcalls = LUAI_MAXCSTACK + CSTACKERR;
400 incnny(L); /* main thread is always non yieldable */
401 g->frealloc = f;
402 g->ud = ud;
403 g->warnf = NULL;
404 g->ud_warn = NULL;
405 g->mainthread = L;
406 g->seed = luai_makeseed(L);
407 g->gcrunning = 0; /* no GC while building state */
408 g->strt.size = g->strt.nuse = 0;
409 g->strt.hash = NULL;
410 setnilvalue(&g->l_registry);
411 g->panic = NULL;
412 g->gcstate = GCSpause;
413 g->gckind = KGC_INC;
414 g->gcemergency = 0;
415 g->finobj = g->tobefnz = g->fixedgc = NULL;
416 g->firstold1 = g->survival = g->old1 = g->reallyold = NULL;
417 g->finobjsur = g->finobjold1 = g->finobjrold = NULL;
418 g->sweepgc = NULL;
419 g->gray = g->grayagain = NULL;
420 g->weak = g->ephemeron = g->allweak = NULL;
421 g->twups = NULL;
422 g->totalbytes = sizeof(LG);
423 g->GCdebt = 0;
424 g->lastatomic = 0;
425 setivalue(&g->nilvalue, 0); /* to signal that state is not yet built */
426 setgcparam(g->gcpause, LUAI_GCPAUSE);
427 setgcparam(g->gcstepmul, LUAI_GCMUL);
428 g->gcstepsize = LUAI_GCSTEPSIZE;
429 setgcparam(g->genmajormul, LUAI_GENMAJORMUL);
430 g->genminormul = LUAI_GENMINORMUL;
431 for (i=0; i < LUA_NUMTAGS; i++) g->mt[i] = NULL;
432 if (luaD_rawrunprotected(L, f_luaopen, NULL) != LUA_OK) {
433 /* memory allocation error: free partial state */
434 close_state(L);
435 L = NULL;
436 }
437 return L;
438 }
439
440
lua_close(lua_State * L)441 LUA_API void lua_close (lua_State *L) {
442 lua_lock(L);
443 L = G(L)->mainthread; /* only the main thread can be closed */
444 close_state(L);
445 }
446
447
luaE_warning(lua_State * L,const char * msg,int tocont)448 void luaE_warning (lua_State *L, const char *msg, int tocont) {
449 lua_WarnFunction wf = G(L)->warnf;
450 if (wf != NULL)
451 wf(G(L)->ud_warn, msg, tocont);
452 }
453
454
455 /*
456 ** Generate a warning from an error message
457 */
luaE_warnerror(lua_State * L,const char * where)458 void luaE_warnerror (lua_State *L, const char *where) {
459 TValue *errobj = s2v(L->top - 1); /* error object */
460 const char *msg = (ttisstring(errobj))
461 ? svalue(errobj)
462 : "error object is not a string";
463 /* produce warning "error in %s (%s)" (where, msg) */
464 luaE_warning(L, "error in ", 1);
465 luaE_warning(L, where, 1);
466 luaE_warning(L, " (", 1);
467 luaE_warning(L, msg, 1);
468 luaE_warning(L, ")", 0);
469 }
470
471