xref: /freebsd/contrib/lua/src/lstate.c (revision a9490b81b032b43cdb3c8c76b4d01bbad9ff82c1)
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);
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   UNUSED(L); UNUSED(limit);
101   return LUAI_MAXCCALLS;  /* warning?? */
102 }
103 
104 
luaE_extendCI(lua_State * L)105 CallInfo *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 */
luaE_freeCI(lua_State * L)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     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 */
luaE_shrinkCI(lua_State * L)138 void 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 */
luaE_checkcstack(lua_State * L)165 void 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 handling stack error */
170 }
171 
172 
luaE_incCstack(lua_State * L)173 LUAI_FUNC void luaE_incCstack (lua_State *L) {
174   L->nCcalls++;
175   if (l_unlikely(getCcalls(L) >= LUAI_MAXCCALLS))
176     luaE_checkcstack(L);
177 }
178 
179 
stack_init(lua_State * L1,lua_State * L)180 static void stack_init (lua_State *L1, lua_State *L) {
181   int i; CallInfo *ci;
182   /* initialize stack array */
183   L1->stack.p = luaM_newvector(L, BASIC_STACK_SIZE + EXTRA_STACK, StackValue);
184   L1->tbclist.p = L1->stack.p;
185   for (i = 0; i < BASIC_STACK_SIZE + EXTRA_STACK; i++)
186     setnilvalue(s2v(L1->stack.p + i));  /* erase new stack */
187   L1->top.p = L1->stack.p;
188   L1->stack_last.p = L1->stack.p + BASIC_STACK_SIZE;
189   /* initialize first ci */
190   ci = &L1->base_ci;
191   ci->next = ci->previous = NULL;
192   ci->callstatus = CIST_C;
193   ci->func.p = L1->top.p;
194   ci->u.c.k = NULL;
195   ci->nresults = 0;
196   setnilvalue(s2v(L1->top.p));  /* 'function' entry for this 'ci' */
197   L1->top.p++;
198   ci->top.p = L1->top.p + LUA_MINSTACK;
199   L1->ci = ci;
200 }
201 
202 
freestack(lua_State * L)203 static void freestack (lua_State *L) {
204   if (L->stack.p == NULL)
205     return;  /* stack not completely built yet */
206   L->ci = &L->base_ci;  /* free the entire 'ci' list */
207   luaE_freeCI(L);
208   lua_assert(L->nci == 0);
209   luaM_freearray(L, L->stack.p, stacksize(L) + EXTRA_STACK);  /* free stack */
210 }
211 
212 
213 /*
214 ** Create registry table and its predefined values
215 */
init_registry(lua_State * L,global_State * g)216 static void init_registry (lua_State *L, global_State *g) {
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, &registry->array[LUA_RIDX_MAINTHREAD - 1], L);
223   /* registry[LUA_RIDX_GLOBALS] = new table (table of globals) */
224   sethvalue(L, &registry->array[LUA_RIDX_GLOBALS - 1], luaH_new(L));
225 }
226 
227 
228 /*
229 ** open parts of the state that may cause memory-allocation errors.
230 */
f_luaopen(lua_State * L,void * ud)231 static void f_luaopen (lua_State *L, void *ud) {
232   global_State *g = G(L);
233   UNUSED(ud);
234   stack_init(L, L);  /* init stack */
235   init_registry(L, g);
236   luaS_init(L);
237   luaT_init(L);
238   luaX_init(L);
239   g->gcstp = 0;  /* allow gc */
240   setnilvalue(&g->nilvalue);  /* now state is complete */
241   luai_userstateopen(L);
242 }
243 
244 
245 /*
246 ** preinitialize a thread with consistent values without allocating
247 ** any memory (to avoid errors)
248 */
preinit_thread(lua_State * L,global_State * g)249 static void preinit_thread (lua_State *L, global_State *g) {
250   G(L) = g;
251   L->stack.p = NULL;
252   L->ci = NULL;
253   L->nci = 0;
254   L->twups = L;  /* thread has no upvalues */
255   L->nCcalls = 0;
256   L->errorJmp = NULL;
257   L->hook = NULL;
258   L->hookmask = 0;
259   L->basehookcount = 0;
260   L->allowhook = 1;
261   resethookcount(L);
262   L->openupval = NULL;
263   L->status = LUA_OK;
264   L->errfunc = 0;
265   L->oldpc = 0;
266 }
267 
268 
close_state(lua_State * L)269 static void close_state (lua_State *L) {
270   global_State *g = G(L);
271   if (!completestate(g))  /* closing a partially built state? */
272     luaC_freeallobjects(L);  /* just collect its objects */
273   else {  /* closing a fully built state */
274     L->ci = &L->base_ci;  /* unwind CallInfo list */
275     luaD_closeprotected(L, 1, LUA_OK);  /* close all upvalues */
276     luaC_freeallobjects(L);  /* collect all objects */
277     luai_userstateclose(L);
278   }
279   luaM_freearray(L, G(L)->strt.hash, G(L)->strt.size);
280   freestack(L);
281   lua_assert(gettotalbytes(g) == sizeof(LG));
282   (*g->frealloc)(g->ud, fromstate(L), sizeof(LG), 0);  /* free main block */
283 }
284 
285 
lua_newthread(lua_State * L)286 LUA_API lua_State *lua_newthread (lua_State *L) {
287   global_State *g = G(L);
288   GCObject *o;
289   lua_State *L1;
290   lua_lock(L);
291   luaC_checkGC(L);
292   /* create new thread */
293   o = luaC_newobjdt(L, LUA_TTHREAD, sizeof(LX), offsetof(LX, l));
294   L1 = gco2th(o);
295   /* anchor it on L stack */
296   setthvalue2s(L, L->top.p, L1);
297   api_incr_top(L);
298   preinit_thread(L1, g);
299   L1->hookmask = L->hookmask;
300   L1->basehookcount = L->basehookcount;
301   L1->hook = L->hook;
302   resethookcount(L1);
303   /* initialize L1 extra space */
304   memcpy(lua_getextraspace(L1), lua_getextraspace(g->mainthread),
305          LUA_EXTRASPACE);
306   luai_userstatethread(L, L1);
307   stack_init(L1, L);  /* init stack */
308   lua_unlock(L);
309   return L1;
310 }
311 
312 
luaE_freethread(lua_State * L,lua_State * L1)313 void luaE_freethread (lua_State *L, lua_State *L1) {
314   LX *l = fromstate(L1);
315   luaF_closeupval(L1, L1->stack.p);  /* close all upvalues */
316   lua_assert(L1->openupval == NULL);
317   luai_userstatefree(L, L1);
318   freestack(L1);
319   luaM_free(L, l);
320 }
321 
322 
luaE_resetthread(lua_State * L,int status)323 int luaE_resetthread (lua_State *L, int status) {
324   CallInfo *ci = L->ci = &L->base_ci;  /* unwind CallInfo list */
325   setnilvalue(s2v(L->stack.p));  /* 'function' entry for basic 'ci' */
326   ci->func.p = L->stack.p;
327   ci->callstatus = CIST_C;
328   if (status == LUA_YIELD)
329     status = LUA_OK;
330   L->status = LUA_OK;  /* so it can run __close metamethods */
331   status = luaD_closeprotected(L, 1, status);
332   if (status != LUA_OK)  /* errors? */
333     luaD_seterrorobj(L, status, L->stack.p + 1);
334   else
335     L->top.p = L->stack.p + 1;
336   ci->top.p = L->top.p + LUA_MINSTACK;
337   luaD_reallocstack(L, cast_int(ci->top.p - L->stack.p), 0);
338   return status;
339 }
340 
341 
lua_closethread(lua_State * L,lua_State * from)342 LUA_API int lua_closethread (lua_State *L, lua_State *from) {
343   int status;
344   lua_lock(L);
345   L->nCcalls = (from) ? getCcalls(from) : 0;
346   status = luaE_resetthread(L, L->status);
347   lua_unlock(L);
348   return status;
349 }
350 
351 
352 /*
353 ** Deprecated! Use 'lua_closethread' instead.
354 */
lua_resetthread(lua_State * L)355 LUA_API int lua_resetthread (lua_State *L) {
356   return lua_closethread(L, NULL);
357 }
358 
359 
lua_newstate(lua_Alloc f,void * ud)360 LUA_API lua_State *lua_newstate (lua_Alloc f, void *ud) {
361   int i;
362   lua_State *L;
363   global_State *g;
364   LG *l = cast(LG *, (*f)(ud, NULL, LUA_TTHREAD, sizeof(LG)));
365   if (l == NULL) return NULL;
366   L = &l->l.l;
367   g = &l->g;
368   L->tt = LUA_VTHREAD;
369   g->currentwhite = bitmask(WHITE0BIT);
370   L->marked = luaC_white(g);
371   preinit_thread(L, g);
372   g->allgc = obj2gco(L);  /* by now, only object is the main thread */
373   L->next = NULL;
374   incnny(L);  /* main thread is always non yieldable */
375   g->frealloc = f;
376   g->ud = ud;
377   g->warnf = NULL;
378   g->ud_warn = NULL;
379   g->mainthread = L;
380   g->seed = luai_makeseed(L);
381   g->gcstp = GCSTPGC;  /* no GC while building state */
382   g->strt.size = g->strt.nuse = 0;
383   g->strt.hash = NULL;
384   setnilvalue(&g->l_registry);
385   g->panic = NULL;
386   g->gcstate = GCSpause;
387   g->gckind = KGC_INC;
388   g->gcstopem = 0;
389   g->gcemergency = 0;
390   g->finobj = g->tobefnz = g->fixedgc = NULL;
391   g->firstold1 = g->survival = g->old1 = g->reallyold = NULL;
392   g->finobjsur = g->finobjold1 = g->finobjrold = NULL;
393   g->sweepgc = NULL;
394   g->gray = g->grayagain = NULL;
395   g->weak = g->ephemeron = g->allweak = NULL;
396   g->twups = NULL;
397   g->totalbytes = sizeof(LG);
398   g->GCdebt = 0;
399   g->lastatomic = 0;
400   setivalue(&g->nilvalue, 0);  /* to signal that state is not yet built */
401   setgcparam(g->gcpause, LUAI_GCPAUSE);
402   setgcparam(g->gcstepmul, LUAI_GCMUL);
403   g->gcstepsize = LUAI_GCSTEPSIZE;
404   setgcparam(g->genmajormul, LUAI_GENMAJORMUL);
405   g->genminormul = LUAI_GENMINORMUL;
406   for (i=0; i < LUA_NUMTAGS; i++) g->mt[i] = NULL;
407   if (luaD_rawrunprotected(L, f_luaopen, NULL) != LUA_OK) {
408     /* memory allocation error: free partial state */
409     close_state(L);
410     L = NULL;
411   }
412   return L;
413 }
414 
415 
lua_close(lua_State * L)416 LUA_API void lua_close (lua_State *L) {
417   lua_lock(L);
418   L = G(L)->mainthread;  /* only the main thread can be closed */
419   close_state(L);
420 }
421 
422 
luaE_warning(lua_State * L,const char * msg,int tocont)423 void luaE_warning (lua_State *L, const char *msg, int tocont) {
424   lua_WarnFunction wf = G(L)->warnf;
425   if (wf != NULL)
426     wf(G(L)->ud_warn, msg, tocont);
427 }
428 
429 
430 /*
431 ** Generate a warning from an error message
432 */
luaE_warnerror(lua_State * L,const char * where)433 void luaE_warnerror (lua_State *L, const char *where) {
434   TValue *errobj = s2v(L->top.p - 1);  /* error object */
435   const char *msg = (ttisstring(errobj))
436                   ? svalue(errobj)
437                   : "error object is not a string";
438   /* produce warning "error in %s (%s)" (where, msg) */
439   luaE_warning(L, "error in ", 1);
440   luaE_warning(L, where, 1);
441   luaE_warning(L, " (", 1);
442   luaE_warning(L, msg, 1);
443   luaE_warning(L, ")", 0);
444 }
445 
446