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*/
35typedef 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*/
44typedef 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
71static 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);
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*/
89void 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
99LUA_API int lua_setcstacklimit (lua_State *L, unsigned int limit) {
100 UNUSED(L); UNUSED(limit);
101 return LUAI_MAXCCALLS; /* warning?? */
102}
103
104
105CallInfo *luaE_extendCI (lua_State *L) {
106 CallInfo *ci;
107 lua_assert(L->ci->next == NULL);
108 ci = luaM_new(L, CallInfo);
109 lua_assert(L->ci->next == NULL);
110 L->ci->next = ci;
111 ci->previous = L->ci;
112 ci->next = NULL;
113 ci->u.l.trap = 0;
114 L->nci++;
115 return ci;
116}
117
118
119/*
120** free all CallInfo structures not in use by a thread
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 L->nci--;
130 }
131}
132
133
134/*
135** free half of the CallInfo structures not in use by a thread,
136** keeping the first one.
137*/
138void luaE_shrinkCI (lua_State *L) {
139 CallInfo *ci = L->ci->next; /* first free CallInfo */
140 CallInfo *next;
141 if (ci == NULL)
142 return; /* no extra elements */
143 while ((next = ci->next) != NULL) { /* two extra elements? */
144 CallInfo *next2 = next->next; /* next's next */
145 ci->next = next2; /* remove next from the list */
146 L->nci--;
147 luaM_free(L, next); /* free next */
148 if (next2 == NULL)
149 break; /* no more elements */
150 else {
151 next2->previous = ci;
152 ci = next2; /* continue */
153 }
154 }
155}
156
157
158/*
159** Called when 'getCcalls(L)' larger or equal to LUAI_MAXCCALLS.
160** If equal, raises an overflow error. If value is larger than
161** LUAI_MAXCCALLS (which means it is handling an overflow) but
162** not much larger, does not report an error (to allow overflow
163** handling to work).
164*/
165void luaE_checkcstack (lua_State *L) {
166 if (getCcalls(L) == LUAI_MAXCCALLS)
167 luaG_runerror(L, "C stack overflow");
168 else if (getCcalls(L) >= (LUAI_MAXCCALLS / 10 * 11))
169 luaD_throw(L, LUA_ERRERR); /* error while handing stack error */
170}
171
172
173LUAI_FUNC void luaE_incCstack (lua_State *L) {
174 L->nCcalls++;
175 if (unlikely(getCcalls(L) >= LUAI_MAXCCALLS))
176 luaE_checkcstack(L);
177}
178
179
180static void stack_init (lua_State *L1, lua_State *L) {
181 int i; CallInfo *ci;
182 /* initialize stack array */
183 L1->stack = luaM_newvector(L, BASIC_STACK_SIZE + EXTRA_STACK, StackValue);
184 for (i = 0; i < BASIC_STACK_SIZE; i++)
185 setnilvalue(s2v(L1->stack + i)); /* erase new stack */
186 L1->top = L1->stack;
187 L1->stack_last = L1->stack + BASIC_STACK_SIZE;
188 /* initialize first ci */
189 ci = &L1->base_ci;
190 ci->next = ci->previous = NULL;
191 ci->callstatus = CIST_C;
192 ci->func = L1->top;
193 ci->u.c.k = NULL;
194 ci->nresults = 0;
195 setnilvalue(s2v(L1->top)); /* 'function' entry for this 'ci' */
196 L1->top++;
197 ci->top = L1->top + LUA_MINSTACK;
198 L1->ci = ci;
199}
200
201
202static void freestack (lua_State *L) {
203 if (L->stack == NULL)
204 return; /* stack not completely built yet */
205 L->ci = &L->base_ci; /* free the entire 'ci' list */
206 luaE_freeCI(L);
207 lua_assert(L->nci == 0);
208 luaM_freearray(L, L->stack, stacksize(L) + EXTRA_STACK); /* free stack */
209}
210
211
212/*
213** Create registry table and its predefined values
214*/
215static void init_registry (lua_State *L, global_State *g) {
216 TValue temp;
217 /* create registry */
218 Table *registry = luaH_new(L);
219 sethvalue(L, &g->l_registry, registry);
220 luaH_resize(L, registry, LUA_RIDX_LAST, 0);
221 /* registry[LUA_RIDX_MAINTHREAD] = L */
222 setthvalue(L, &temp, L); /* temp = L */
223 luaH_setint(L, registry, LUA_RIDX_MAINTHREAD, &temp);
224 /* registry[LUA_RIDX_GLOBALS] = table of globals */
225 sethvalue(L, &temp, luaH_new(L)); /* temp = new table (global table) */
226 luaH_setint(L, registry, LUA_RIDX_GLOBALS, &temp);
227}
228
229
230/*
231** open parts of the state that may cause memory-allocation errors.
232** ('g->nilvalue' being a nil value flags that the state was completely
233** build.)
234*/
235static void f_luaopen (lua_State *L, void *ud) {
236 global_State *g = G(L);
237 UNUSED(ud);
238 stack_init(L, L); /* init stack */
239 init_registry(L, g);
240 luaS_init(L);
241 luaT_init(L);
242 luaX_init(L);
243 g->gcrunning = 1; /* allow gc */
244 setnilvalue(&g->nilvalue);
245 luai_userstateopen(L);
246}
247
248
249/*
250** preinitialize a thread with consistent values without allocating
251** any memory (to avoid errors)
252*/
253static void preinit_thread (lua_State *L, global_State *g) {
254 G(L) = g;
255 L->stack = NULL;
256 L->ci = NULL;
257 L->nci = 0;
258 L->twups = L; /* thread has no upvalues */
259 L->errorJmp = NULL;
260 L->hook = NULL;
261 L->hookmask = 0;
262 L->basehookcount = 0;
263 L->allowhook = 1;
264 resethookcount(L);
265 L->openupval = NULL;
266 L->status = LUA_OK;
267 L->errfunc = 0;
268 L->oldpc = 0;
269}
270
271
272static void close_state (lua_State *L) {
273 global_State *g = G(L);
274 luaF_close(L, L->stack, CLOSEPROTECT); /* close all upvalues */
275 luaC_freeallobjects(L); /* collect all objects */
276 if (ttisnil(&g->nilvalue)) /* closing a fully built state? */
277 luai_userstateclose(L);
278 luaM_freearray(L, G(L)->strt.hash, G(L)->strt.size);
279 freestack(L);
280 lua_assert(gettotalbytes(g) == sizeof(LG));
281 (*g->frealloc)(g->ud, fromstate(L), sizeof(LG), 0); /* free main block */
282}
283
284
285LUA_API lua_State *lua_newthread (lua_State *L) {
286 global_State *g;
287 lua_State *L1;
288 lua_lock(L);
289 g = G(L);
290 luaC_checkGC(L);
291 /* create new thread */
292 L1 = &cast(LX *, luaM_newobject(L, LUA_TTHREAD, sizeof(LX)))->l;
293 L1->marked = luaC_white(g);
294 L1->tt = LUA_VTHREAD;
295 /* link it on list 'allgc' */
296 L1->next = g->allgc;
297 g->allgc = obj2gco(L1);
298 /* anchor it on L stack */
299 setthvalue2s(L, L->top, L1);
300 api_incr_top(L);
301 preinit_thread(L1, g);
302 L1->nCcalls = 0;
303 L1->hookmask = L->hookmask;
304 L1->basehookcount = L->basehookcount;
305 L1->hook = L->hook;
306 resethookcount(L1);
307 /* initialize L1 extra space */
308 memcpy(lua_getextraspace(L1), lua_getextraspace(g->mainthread),
309 LUA_EXTRASPACE);
310 luai_userstatethread(L, L1);
311 stack_init(L1, L); /* init stack */
312 lua_unlock(L);
313 return L1;
314}
315
316
317void luaE_freethread (lua_State *L, lua_State *L1) {
318 LX *l = fromstate(L1);
319 luaF_close(L1, L1->stack, NOCLOSINGMETH); /* close all upvalues */
320 lua_assert(L1->openupval == NULL);
321 luai_userstatefree(L, L1);
322 freestack(L1);
323 luaM_free(L, l);
324}
325
326
327int lua_resetthread (lua_State *L) {
328 CallInfo *ci;
329 int status;
330 lua_lock(L);
331 L->ci = ci = &L->base_ci; /* unwind CallInfo list */
332 setnilvalue(s2v(L->stack)); /* 'function' entry for basic 'ci' */
333 ci->func = L->stack;
334 ci->callstatus = CIST_C;
335 status = luaF_close(L, L->stack, CLOSEPROTECT);
336 if (status != CLOSEPROTECT) /* real errors? */
337 luaD_seterrorobj(L, status, L->stack + 1);
338 else {
339 status = LUA_OK;
340 L->top = L->stack + 1;
341 }
342 ci->top = L->top + LUA_MINSTACK;
343 L->status = status;
344 lua_unlock(L);
345 return status;
346}
347
348
349LUA_API lua_State *lua_newstate (lua_Alloc f, void *ud) {
350 int i;
351 lua_State *L;
352 global_State *g;
353 LG *l = cast(LG *, (*f)(ud, NULL, LUA_TTHREAD, sizeof(LG)));
354 if (l == NULL) return NULL;
355 L = &l->l.l;
356 g = &l->g;
357 L->tt = LUA_VTHREAD;
358 g->currentwhite = bitmask(WHITE0BIT);
359 L->marked = luaC_white(g);
360 preinit_thread(L, g);
361 g->allgc = obj2gco(L); /* by now, only object is the main thread */
362 L->next = NULL;
363 L->nCcalls = 0;
364 incnny(L); /* main thread is always non yieldable */
365 g->frealloc = f;
366 g->ud = ud;
367 g->warnf = NULL;
368 g->ud_warn = NULL;
369 g->mainthread = L;
370 g->seed = luai_makeseed(L);
371 g->gcrunning = 0; /* no GC while building state */
372 g->strt.size = g->strt.nuse = 0;
373 g->strt.hash = NULL;
374 setnilvalue(&g->l_registry);
375 g->panic = NULL;
376 g->gcstate = GCSpause;
377 g->gckind = KGC_INC;
378 g->gcemergency = 0;
379 g->finobj = g->tobefnz = g->fixedgc = NULL;
380 g->firstold1 = g->survival = g->old1 = g->reallyold = NULL;
381 g->finobjsur = g->finobjold1 = g->finobjrold = NULL;
382 g->sweepgc = NULL;
383 g->gray = g->grayagain = NULL;
384 g->weak = g->ephemeron = g->allweak = NULL;
385 g->twups = NULL;
386 g->totalbytes = sizeof(LG);
387 g->GCdebt = 0;
388 g->lastatomic = 0;
389 setivalue(&g->nilvalue, 0); /* to signal that state is not yet built */
390 setgcparam(g->gcpause, LUAI_GCPAUSE);
391 setgcparam(g->gcstepmul, LUAI_GCMUL);
392 g->gcstepsize = LUAI_GCSTEPSIZE;
393 setgcparam(g->genmajormul, LUAI_GENMAJORMUL);
394 g->genminormul = LUAI_GENMINORMUL;
395 for (i=0; i < LUA_NUMTAGS; i++) g->mt[i] = NULL;
396 if (luaD_rawrunprotected(L, f_luaopen, NULL) != LUA_OK) {
397 /* memory allocation error: free partial state */
398 close_state(L);
399 L = NULL;
400 }
401 return L;
402}
403
404
405LUA_API void lua_close (lua_State *L) {
406 lua_lock(L);
407 L = G(L)->mainthread; /* only the main thread can be closed */
408 close_state(L);
409}
410
411
412void luaE_warning (lua_State *L, const char *msg, int tocont) {
413 lua_WarnFunction wf = G(L)->warnf;
414 if (wf != NULL)
415 wf(G(L)->ud_warn, msg, tocont);
416}
417
418
419/*
420** Generate a warning from an error message
421*/
422void luaE_warnerror (lua_State *L, const char *where) {
423 TValue *errobj = s2v(L->top - 1); /* error object */
424 const char *msg = (ttisstring(errobj))
425 ? svalue(errobj)
426 : "error object is not a string";
427 /* produce warning "error in %s (%s)" (where, msg) */
428 luaE_warning(L, "error in ", 1);
429 luaE_warning(L, where, 1);
430 luaE_warning(L, " (", 1);
431 luaE_warning(L, msg, 1);
432 luaE_warning(L, ")", 0);
433}
434
435