2 ** $Id: ldo.c,v 2.108.1.3 2013/11/08 18:22:50 roberto Exp $
3 ** Stack and Call structure of Lua
4 ** See Copyright Notice in lua.h
38 ** {======================================================
39 ** Error-recovery functions
40 ** =======================================================
44 ** LUAI_THROW/LUAI_TRY define how Lua does exception handling. By
45 ** default, Lua handles errors with exceptions when compiling as
46 ** C++ code, with _longjmp/_setjmp when asked to use them, and with
47 ** longjmp/setjmp otherwise.
49 #if !defined(LUAI_THROW)
51 #if defined(__cplusplus) && !defined(LUA_USE_LONGJMP)
53 #define LUAI_THROW(L,c) throw(c)
54 #define LUAI_TRY(L,c,a) \
55 try { a } catch(...) { if ((c)->status == 0) (c)->status = -1; }
56 #define luai_jmpbuf int /* dummy variable */
58 #elif defined(LUA_USE_ULONGJMP)
59 /* in Unix, try _longjmp/_setjmp (more efficient) */
60 #define LUAI_THROW(L,c) _longjmp((c)->b, 1)
61 #define LUAI_TRY(L,c,a) if (_setjmp((c)->b) == 0) { a }
62 #define luai_jmpbuf jmp_buf
65 /* default handling with long jumps */
66 #define LUAI_THROW(L,c) longjmp((c)->b, 1)
67 #define LUAI_TRY(L,c,a) if (setjmp((c)->b) == 0) { a }
68 #define luai_jmpbuf jmp_buf
76 /* chain list of long jump buffers */
78 struct lua_longjmp *previous;
80 volatile int status; /* error code */
84 static void seterrorobj (lua_State *L, int errcode, StkId oldtop) {
86 case LUA_ERRMEM: { /* memory error? */
87 setsvalue2s(L, oldtop, G(L)->memerrmsg); /* reuse preregistered msg. */
91 setsvalue2s(L, oldtop, luaS_newliteral(L, "error in error handling"));
95 setobjs2s(L, oldtop, L->top - 1); /* error message on current top */
103 l_noret luaD_throw (lua_State *L, int errcode) {
104 if (L->errorJmp) { /* thread has an error handler? */
105 L->errorJmp->status = errcode; /* set status */
106 LUAI_THROW(L, L->errorJmp); /* jump to it */
108 else { /* thread has no error handler */
109 L->status = cast_byte(errcode); /* mark it as dead */
110 if (G(L)->mainthread->errorJmp) { /* main thread has a handler? */
111 setobjs2s(L, G(L)->mainthread->top++, L->top - 1); /* copy error obj. */
112 luaD_throw(G(L)->mainthread, errcode); /* re-throw in main thread */
114 else { /* no handler at all; abort */
115 if (G(L)->panic) { /* panic function? */
117 G(L)->panic(L); /* call it (last chance to jump out) */
125 int luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud) {
126 unsigned short oldnCcalls = L->nCcalls;
127 struct lua_longjmp lj;
129 lj.previous = L->errorJmp; /* chain new error handler */
134 L->errorJmp = lj.previous; /* restore old error handler */
135 L->nCcalls = oldnCcalls;
139 /* }====================================================== */
142 static void correctstack (lua_State *L, TValue *oldstack) {
145 L->top = (L->top - oldstack) + L->stack;
146 for (up = L->openupval; up != NULL; up = up->gch.next)
147 gco2uv(up)->v = (gco2uv(up)->v - oldstack) + L->stack;
148 for (ci = L->ci; ci != NULL; ci = ci->previous) {
149 ci->top = (ci->top - oldstack) + L->stack;
150 ci->func = (ci->func - oldstack) + L->stack;
152 ci->u.l.base = (ci->u.l.base - oldstack) + L->stack;
157 /* some space for error handling */
158 #define ERRORSTACKSIZE (LUAI_MAXSTACK + 200)
161 void luaD_reallocstack (lua_State *L, int newsize) {
162 TValue *oldstack = L->stack;
163 int lim = L->stacksize;
164 lua_assert(newsize <= LUAI_MAXSTACK || newsize == ERRORSTACKSIZE);
165 lua_assert(L->stack_last - L->stack == L->stacksize - EXTRA_STACK);
166 luaM_reallocvector(L, L->stack, L->stacksize, newsize, TValue);
167 for (; lim < newsize; lim++)
168 setnilvalue(L->stack + lim); /* erase new segment */
169 L->stacksize = newsize;
170 L->stack_last = L->stack + newsize - EXTRA_STACK;
171 correctstack(L, oldstack);
175 void luaD_growstack (lua_State *L, int n) {
176 int size = L->stacksize;
177 if (size > LUAI_MAXSTACK) /* error after extra size? */
178 luaD_throw(L, LUA_ERRERR);
180 int needed = cast_int(L->top - L->stack) + n + EXTRA_STACK;
181 int newsize = 2 * size;
182 if (newsize > LUAI_MAXSTACK) newsize = LUAI_MAXSTACK;
183 if (newsize < needed) newsize = needed;
184 if (newsize > LUAI_MAXSTACK) { /* stack overflow? */
185 luaD_reallocstack(L, ERRORSTACKSIZE);
186 luaG_runerror(L, "stack overflow");
189 luaD_reallocstack(L, newsize);
194 static int stackinuse (lua_State *L) {
197 for (ci = L->ci; ci != NULL; ci = ci->previous) {
198 lua_assert(ci->top <= L->stack_last);
199 if (lim < ci->top) lim = ci->top;
201 return cast_int(lim - L->stack) + 1; /* part of stack in use */
205 void luaD_shrinkstack (lua_State *L) {
206 int inuse = stackinuse(L);
207 int goodsize = inuse + (inuse / 8) + 2*EXTRA_STACK;
208 if (goodsize > LUAI_MAXSTACK) goodsize = LUAI_MAXSTACK;
209 if (inuse > LUAI_MAXSTACK || /* handling stack overflow? */
210 goodsize >= L->stacksize) /* would grow instead of shrink? */
211 condmovestack(L); /* don't change stack (change only for debugging) */
213 luaD_reallocstack(L, goodsize); /* shrink it */
217 void luaD_hook (lua_State *L, int event, int line) {
218 lua_Hook hook = L->hook;
219 if (hook && L->allowhook) {
220 CallInfo *ci = L->ci;
221 ptrdiff_t top = savestack(L, L->top);
222 ptrdiff_t ci_top = savestack(L, ci->top);
225 ar.currentline = line;
227 luaD_checkstack(L, LUA_MINSTACK); /* ensure minimum stack size */
228 ci->top = L->top + LUA_MINSTACK;
229 lua_assert(ci->top <= L->stack_last);
230 L->allowhook = 0; /* cannot call hooks inside a hook */
231 ci->callstatus |= CIST_HOOKED;
235 lua_assert(!L->allowhook);
237 ci->top = restorestack(L, ci_top);
238 L->top = restorestack(L, top);
239 ci->callstatus &= ~CIST_HOOKED;
244 static void callhook (lua_State *L, CallInfo *ci) {
245 int hook = LUA_HOOKCALL;
246 ci->u.l.savedpc++; /* hooks assume 'pc' is already incremented */
247 if (isLua(ci->previous) &&
248 GET_OPCODE(*(ci->previous->u.l.savedpc - 1)) == OP_TAILCALL) {
249 ci->callstatus |= CIST_TAIL;
250 hook = LUA_HOOKTAILCALL;
252 luaD_hook(L, hook, -1);
253 ci->u.l.savedpc--; /* correct 'pc' */
257 static StkId adjust_varargs (lua_State *L, Proto *p, int actual) {
259 int nfixargs = p->numparams;
261 lua_assert(actual >= nfixargs);
262 /* move fixed parameters to final position */
263 luaD_checkstack(L, p->maxstacksize); /* check again for new 'base' */
264 fixed = L->top - actual; /* first fixed argument */
265 base = L->top; /* final position of first argument */
266 for (i=0; i<nfixargs; i++) {
267 setobjs2s(L, L->top++, fixed + i);
268 setnilvalue(fixed + i);
274 static StkId tryfuncTM (lua_State *L, StkId func) {
275 const TValue *tm = luaT_gettmbyobj(L, func, TM_CALL);
277 ptrdiff_t funcr = savestack(L, func);
278 if (!ttisfunction(tm))
279 luaG_typeerror(L, func, "call");
280 /* Open a hole inside the stack at `func' */
281 for (p = L->top; p > func; p--) setobjs2s(L, p, p-1);
283 func = restorestack(L, funcr); /* previous call may change stack */
284 setobj2s(L, func, tm); /* tag method is the new function to be called */
290 #define next_ci(L) (L->ci = (L->ci->next ? L->ci->next : luaE_extendCI(L)))
294 ** returns true if function has been executed (C function)
296 int luaD_precall (lua_State *L, StkId func, int nresults) {
299 int n; /* number of arguments (Lua) or returns (C) */
300 ptrdiff_t funcr = savestack(L, func);
301 switch (ttype(func)) {
302 case LUA_TLCF: /* light C function */
305 case LUA_TCCL: { /* C closure */
306 f = clCvalue(func)->f;
308 luaD_checkstack(L, LUA_MINSTACK); /* ensure minimum stack size */
309 ci = next_ci(L); /* now 'enter' new function */
310 ci->nresults = nresults;
311 ci->func = restorestack(L, funcr);
312 ci->top = L->top + LUA_MINSTACK;
313 lua_assert(ci->top <= L->stack_last);
315 luaC_checkGC(L); /* stack grow uses memory */
316 if (L->hookmask & LUA_MASKCALL)
317 luaD_hook(L, LUA_HOOKCALL, -1);
319 n = (*f)(L); /* do the actual call */
321 api_checknelems(L, n);
322 luaD_poscall(L, L->top - n);
325 case LUA_TLCL: { /* Lua function: prepare its call */
327 Proto *p = clLvalue(func)->p;
328 n = cast_int(L->top - func) - 1; /* number of real arguments */
329 luaD_checkstack(L, p->maxstacksize);
330 for (; n < p->numparams; n++)
331 setnilvalue(L->top++); /* complete missing arguments */
333 func = restorestack(L, funcr);
337 base = adjust_varargs(L, p, n);
338 func = restorestack(L, funcr); /* previous call can change stack */
340 ci = next_ci(L); /* now 'enter' new function */
341 ci->nresults = nresults;
344 ci->top = base + p->maxstacksize;
345 lua_assert(ci->top <= L->stack_last);
346 ci->u.l.savedpc = p->code; /* starting point */
347 ci->callstatus = CIST_LUA;
349 luaC_checkGC(L); /* stack grow uses memory */
350 if (L->hookmask & LUA_MASKCALL)
354 default: { /* not a function */
355 func = tryfuncTM(L, func); /* retry with 'function' tag method */
356 return luaD_precall(L, func, nresults); /* now it must be a function */
362 int luaD_poscall (lua_State *L, StkId firstResult) {
365 CallInfo *ci = L->ci;
366 if (L->hookmask & (LUA_MASKRET | LUA_MASKLINE)) {
367 if (L->hookmask & LUA_MASKRET) {
368 ptrdiff_t fr = savestack(L, firstResult); /* hook may change stack */
369 luaD_hook(L, LUA_HOOKRET, -1);
370 firstResult = restorestack(L, fr);
372 L->oldpc = ci->previous->u.l.savedpc; /* 'oldpc' for caller function */
374 res = ci->func; /* res == final position of 1st result */
375 wanted = ci->nresults;
376 L->ci = ci = ci->previous; /* back to caller */
377 /* move results to correct place */
378 for (i = wanted; i != 0 && firstResult < L->top; i--)
379 setobjs2s(L, res++, firstResult++);
383 return (wanted - LUA_MULTRET); /* 0 iff wanted == LUA_MULTRET */
388 ** Call a function (C or Lua). The function to be called is at *func.
389 ** The arguments are on the stack, right after the function.
390 ** When returns, all the results are on the stack, starting at the original
391 ** function position.
393 void luaD_call (lua_State *L, StkId func, int nResults, int allowyield) {
394 if (++L->nCcalls >= LUAI_MAXCCALLS) {
395 if (L->nCcalls == LUAI_MAXCCALLS)
396 luaG_runerror(L, "C stack overflow");
397 else if (L->nCcalls >= (LUAI_MAXCCALLS + (LUAI_MAXCCALLS>>3)))
398 luaD_throw(L, LUA_ERRERR); /* error while handing stack error */
400 if (!allowyield) L->nny++;
401 if (!luaD_precall(L, func, nResults)) /* is a Lua function? */
402 luaV_execute(L); /* call it */
403 if (!allowyield) L->nny--;
408 static void finishCcall (lua_State *L) {
409 CallInfo *ci = L->ci;
411 lua_assert(ci->u.c.k != NULL); /* must have a continuation */
412 lua_assert(L->nny == 0);
413 if (ci->callstatus & CIST_YPCALL) { /* was inside a pcall? */
414 ci->callstatus &= ~CIST_YPCALL; /* finish 'lua_pcall' */
415 L->errfunc = ci->u.c.old_errfunc;
417 /* finish 'lua_callk'/'lua_pcall' */
418 adjustresults(L, ci->nresults);
419 /* call continuation function */
420 if (!(ci->callstatus & CIST_STAT)) /* no call status? */
421 ci->u.c.status = LUA_YIELD; /* 'default' status */
422 lua_assert(ci->u.c.status != LUA_OK);
423 ci->callstatus = (ci->callstatus & ~(CIST_YPCALL | CIST_STAT)) | CIST_YIELDED;
427 api_checknelems(L, n);
428 /* finish 'luaD_precall' */
429 luaD_poscall(L, L->top - n);
433 static void unroll (lua_State *L, void *ud) {
436 if (L->ci == &L->base_ci) /* stack is empty? */
437 return; /* coroutine finished normally */
438 if (!isLua(L->ci)) /* C function? */
440 else { /* Lua function */
441 luaV_finishOp(L); /* finish interrupted instruction */
442 luaV_execute(L); /* execute down to higher C 'boundary' */
449 ** check whether thread has a suspended protected call
451 static CallInfo *findpcall (lua_State *L) {
453 for (ci = L->ci; ci != NULL; ci = ci->previous) { /* search for a pcall */
454 if (ci->callstatus & CIST_YPCALL)
457 return NULL; /* no pending pcall */
461 static int recover (lua_State *L, int status) {
463 CallInfo *ci = findpcall(L);
464 if (ci == NULL) return 0; /* no recovery point */
465 /* "finish" luaD_pcall */
466 oldtop = restorestack(L, ci->extra);
467 luaF_close(L, oldtop);
468 seterrorobj(L, status, oldtop);
470 L->allowhook = ci->u.c.old_allowhook;
471 L->nny = 0; /* should be zero to be yieldable */
473 L->errfunc = ci->u.c.old_errfunc;
474 ci->callstatus |= CIST_STAT; /* call has error status */
475 ci->u.c.status = status; /* (here it is) */
476 return 1; /* continue running the coroutine */
481 ** signal an error in the call to 'resume', not in the execution of the
482 ** coroutine itself. (Such errors should not be handled by any coroutine
483 ** error handler and should not kill the coroutine.)
485 static l_noret resume_error (lua_State *L, const char *msg, StkId firstArg) {
486 L->top = firstArg; /* remove args from the stack */
487 setsvalue2s(L, L->top, luaS_new(L, msg)); /* push error message */
489 luaD_throw(L, -1); /* jump back to 'lua_resume' */
494 ** do the work for 'lua_resume' in protected mode
496 static void resume (lua_State *L, void *ud) {
497 int nCcalls = L->nCcalls;
498 StkId firstArg = cast(StkId, ud);
499 CallInfo *ci = L->ci;
500 if (nCcalls >= LUAI_MAXCCALLS)
501 resume_error(L, "C stack overflow", firstArg);
502 if (L->status == LUA_OK) { /* may be starting a coroutine */
503 if (ci != &L->base_ci) /* not in base level? */
504 resume_error(L, "cannot resume non-suspended coroutine", firstArg);
505 /* coroutine is in base level; start running it */
506 if (!luaD_precall(L, firstArg - 1, LUA_MULTRET)) /* Lua function? */
507 luaV_execute(L); /* call it */
509 else if (L->status != LUA_YIELD)
510 resume_error(L, "cannot resume dead coroutine", firstArg);
511 else { /* resuming from previous yield */
513 ci->func = restorestack(L, ci->extra);
514 if (isLua(ci)) /* yielded inside a hook? */
515 luaV_execute(L); /* just continue running Lua code */
516 else { /* 'common' yield */
517 if (ci->u.c.k != NULL) { /* does it have a continuation? */
519 ci->u.c.status = LUA_YIELD; /* 'default' status */
520 ci->callstatus |= CIST_YIELDED;
522 n = (*ci->u.c.k)(L); /* call continuation */
524 api_checknelems(L, n);
525 firstArg = L->top - n; /* yield results come from continuation */
527 luaD_poscall(L, firstArg); /* finish 'luaD_precall' */
531 lua_assert(nCcalls == L->nCcalls);
535 LUA_API int lua_resume (lua_State *L, lua_State *from, int nargs) {
537 int oldnny = L->nny; /* save 'nny' */
539 luai_userstateresume(L, nargs);
540 L->nCcalls = (from) ? from->nCcalls + 1 : 1;
541 L->nny = 0; /* allow yields */
542 api_checknelems(L, (L->status == LUA_OK) ? nargs + 1 : nargs);
543 status = luaD_rawrunprotected(L, resume, L->top - nargs);
544 if (status == -1) /* error calling 'lua_resume'? */
546 else { /* yield or regular error */
547 while (status != LUA_OK && status != LUA_YIELD) { /* error? */
548 if (recover(L, status)) /* recover point? */
549 status = luaD_rawrunprotected(L, unroll, NULL); /* run continuation */
550 else { /* unrecoverable error */
551 L->status = cast_byte(status); /* mark thread as `dead' */
552 seterrorobj(L, status, L->top);
557 lua_assert(status == L->status);
559 L->nny = oldnny; /* restore 'nny' */
561 lua_assert(L->nCcalls == ((from) ? from->nCcalls : 0));
567 LUA_API int lua_yieldk (lua_State *L, int nresults, int ctx, lua_CFunction k) {
568 CallInfo *ci = L->ci;
569 luai_userstateyield(L, nresults);
571 api_checknelems(L, nresults);
573 if (L != G(L)->mainthread)
574 luaG_runerror(L, "attempt to yield across a C-call boundary");
576 luaG_runerror(L, "attempt to yield from outside a coroutine");
578 L->status = LUA_YIELD;
579 ci->extra = savestack(L, ci->func); /* save current 'func' */
580 if (isLua(ci)) { /* inside a hook? */
581 api_check(L, k == NULL, "hooks cannot continue after yielding");
584 if ((ci->u.c.k = k) != NULL) /* is there a continuation? */
585 ci->u.c.ctx = ctx; /* save context */
586 ci->func = L->top - nresults - 1; /* protect stack below results */
587 luaD_throw(L, LUA_YIELD);
589 lua_assert(ci->callstatus & CIST_HOOKED); /* must be inside a hook */
591 return 0; /* return to 'luaD_hook' */
595 int luaD_pcall (lua_State *L, Pfunc func, void *u,
596 ptrdiff_t old_top, ptrdiff_t ef) {
598 CallInfo *old_ci = L->ci;
599 lu_byte old_allowhooks = L->allowhook;
600 unsigned short old_nny = L->nny;
601 ptrdiff_t old_errfunc = L->errfunc;
603 status = luaD_rawrunprotected(L, func, u);
604 if (status != LUA_OK) { /* an error occurred? */
605 StkId oldtop = restorestack(L, old_top);
606 luaF_close(L, oldtop); /* close possible pending closures */
607 seterrorobj(L, status, oldtop);
609 L->allowhook = old_allowhooks;
613 L->errfunc = old_errfunc;
620 ** Execute a protected parser.
622 struct SParser { /* data to `f_parser' */
624 Mbuffer buff; /* dynamic structure used by the scanner */
625 Dyndata dyd; /* dynamic structures used by the parser */
631 static void checkmode (lua_State *L, const char *mode, const char *x) {
632 if (mode && strchr(mode, x[0]) == NULL) {
634 "attempt to load a %s chunk (mode is " LUA_QS ")", x, mode);
635 luaD_throw(L, LUA_ERRSYNTAX);
640 static void f_parser (lua_State *L, void *ud) {
643 struct SParser *p = cast(struct SParser *, ud);
644 int c = zgetc(p->z); /* read first character */
645 if (c == LUA_SIGNATURE[0]) {
646 checkmode(L, p->mode, "binary");
647 cl = luaU_undump(L, p->z, &p->buff, p->name);
650 checkmode(L, p->mode, "text");
651 cl = luaY_parser(L, p->z, &p->buff, &p->dyd, p->name, c);
653 lua_assert(cl->l.nupvalues == cl->l.p->sizeupvalues);
654 for (i = 0; i < cl->l.nupvalues; i++) { /* initialize upvalues */
655 UpVal *up = luaF_newupval(L);
656 cl->l.upvals[i] = up;
657 luaC_objbarrier(L, cl, up);
662 int luaD_protectedparser (lua_State *L, ZIO *z, const char *name,
666 L->nny++; /* cannot yield during parsing */
667 p.z = z; p.name = name; p.mode = mode;
668 p.dyd.actvar.arr = NULL; p.dyd.actvar.size = 0;
669 p.dyd.gt.arr = NULL; p.dyd.gt.size = 0;
670 p.dyd.label.arr = NULL; p.dyd.label.size = 0;
671 luaZ_initbuffer(L, &p.buff);
672 status = luaD_pcall(L, f_parser, &p, savestack(L, L->top), L->errfunc);
673 luaZ_freebuffer(L, &p.buff);
674 luaM_freearray(L, p.dyd.actvar.arr, p.dyd.actvar.size);
675 luaM_freearray(L, p.dyd.gt.arr, p.dyd.gt.size);
676 luaM_freearray(L, p.dyd.label.arr, p.dyd.label.size);