2 ** $Id: ldo.c,v 2.38.1.3 2008/01/18 22:31:22 roberto Exp $
3 ** Stack and Call structure of Lua
4 ** See Copyright Notice in lua.h
37 ** {======================================================
38 ** Error-recovery functions
39 ** =======================================================
43 /* chain list of long jump buffers */
45 struct lua_longjmp *previous;
47 volatile int status; /* error code */
51 void luaD_seterrorobj (lua_State *L, int errcode, StkId oldtop) {
54 setsvalue2s(L, oldtop, luaS_newliteral(L, MEMERRMSG));
58 setsvalue2s(L, oldtop, luaS_newliteral(L, "error in error handling"));
63 setobjs2s(L, oldtop, L->top - 1); /* error message on current top */
71 static void restore_stack_limit (lua_State *L) {
72 lua_assert(L->stack_last - L->stack == L->stacksize - EXTRA_STACK - 1);
73 if (L->size_ci > LUAI_MAXCALLS) { /* there was an overflow? */
74 int inuse = cast_int(L->ci - L->base_ci);
75 if (inuse + 1 < LUAI_MAXCALLS) /* can `undo' overflow? */
76 luaD_reallocCI(L, LUAI_MAXCALLS);
81 static void resetstack (lua_State *L, int status) {
83 L->base = L->ci->base;
84 luaF_close(L, L->base); /* close eventual pending closures */
85 luaD_seterrorobj(L, status, L->base);
86 L->nCcalls = L->baseCcalls;
88 restore_stack_limit(L);
94 void luaD_throw (lua_State *L, int errcode) {
96 L->errorJmp->status = errcode;
97 LUAI_THROW(L, L->errorJmp);
100 L->status = cast_byte(errcode);
102 resetstack(L, errcode);
111 int luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud) {
112 struct lua_longjmp lj;
114 lj.previous = L->errorJmp; /* chain new error handler */
119 L->errorJmp = lj.previous; /* restore old error handler */
123 /* }====================================================== */
126 static void correctstack (lua_State *L, TValue *oldstack) {
129 L->top = (L->top - oldstack) + L->stack;
130 for (up = L->openupval; up != NULL; up = up->gch.next)
131 gco2uv(up)->v = (gco2uv(up)->v - oldstack) + L->stack;
132 for (ci = L->base_ci; ci <= L->ci; ci++) {
133 ci->top = (ci->top - oldstack) + L->stack;
134 ci->base = (ci->base - oldstack) + L->stack;
135 ci->func = (ci->func - oldstack) + L->stack;
137 L->base = (L->base - oldstack) + L->stack;
141 void luaD_reallocstack (lua_State *L, int newsize) {
142 TValue *oldstack = L->stack;
143 int realsize = newsize + 1 + EXTRA_STACK;
144 lua_assert(L->stack_last - L->stack == L->stacksize - EXTRA_STACK - 1);
145 luaM_reallocvector(L, L->stack, L->stacksize, realsize, TValue);
146 L->stacksize = realsize;
147 L->stack_last = L->stack+newsize;
148 correctstack(L, oldstack);
152 void luaD_reallocCI (lua_State *L, int newsize) {
153 CallInfo *oldci = L->base_ci;
154 luaM_reallocvector(L, L->base_ci, L->size_ci, newsize, CallInfo);
155 L->size_ci = newsize;
156 L->ci = (L->ci - oldci) + L->base_ci;
157 L->end_ci = L->base_ci + L->size_ci - 1;
161 void luaD_growstack (lua_State *L, int n) {
162 if (n <= L->stacksize) /* double size is enough? */
163 luaD_reallocstack(L, 2*L->stacksize);
165 luaD_reallocstack(L, L->stacksize + n);
169 static CallInfo *growCI (lua_State *L) {
170 if (L->size_ci > LUAI_MAXCALLS) /* overflow while handling overflow? */
171 luaD_throw(L, LUA_ERRERR);
173 luaD_reallocCI(L, 2*L->size_ci);
174 if (L->size_ci > LUAI_MAXCALLS)
175 luaG_runerror(L, "stack overflow");
181 void luaD_callhook (lua_State *L, int event, int line) {
182 lua_Hook hook = L->hook;
183 if (hook && L->allowhook) {
184 ptrdiff_t top = savestack(L, L->top);
185 ptrdiff_t ci_top = savestack(L, L->ci->top);
188 ar.currentline = line;
189 if (event == LUA_HOOKTAILRET)
190 ar.i_ci = 0; /* tail call; no debug information about it */
192 ar.i_ci = cast_int(L->ci - L->base_ci);
193 luaD_checkstack(L, LUA_MINSTACK); /* ensure minimum stack size */
194 L->ci->top = L->top + LUA_MINSTACK;
195 lua_assert(L->ci->top <= L->stack_last);
196 L->allowhook = 0; /* cannot call hooks inside a hook */
200 lua_assert(!L->allowhook);
202 L->ci->top = restorestack(L, ci_top);
203 L->top = restorestack(L, top);
208 static StkId adjust_varargs (lua_State *L, Proto *p, int actual) {
210 int nfixargs = p->numparams;
213 for (; actual < nfixargs; ++actual)
214 setnilvalue(L->top++);
215 #if defined(LUA_COMPAT_VARARG)
216 if (p->is_vararg & VARARG_NEEDSARG) { /* compat. with old-style vararg? */
217 int nvar = actual - nfixargs; /* number of extra arguments */
218 lua_assert(p->is_vararg & VARARG_HASARG);
220 htab = luaH_new(L, nvar, 1); /* create `arg' table */
221 for (i=0; i<nvar; i++) /* put extra arguments into `arg' table */
222 setobj2n(L, luaH_setnum(L, htab, i+1), L->top - nvar + i);
223 /* store counter in field `n' */
224 setnvalue(luaH_setstr(L, htab, luaS_newliteral(L, "n")), cast_num(nvar));
227 /* move fixed parameters to final position */
228 fixed = L->top - actual; /* first fixed argument */
229 base = L->top; /* final position of first argument */
230 for (i=0; i<nfixargs; i++) {
231 setobjs2s(L, L->top++, fixed+i);
232 setnilvalue(fixed+i);
234 /* add `arg' parameter */
236 sethvalue(L, L->top++, htab);
237 lua_assert(iswhite(obj2gco(htab)));
243 static StkId tryfuncTM (lua_State *L, StkId func) {
244 const TValue *tm = luaT_gettmbyobj(L, func, TM_CALL);
246 ptrdiff_t funcr = savestack(L, func);
247 if (!ttisfunction(tm))
248 luaG_typeerror(L, func, "call");
249 /* Open a hole inside the stack at `func' */
250 for (p = L->top; p > func; p--) setobjs2s(L, p, p-1);
252 func = restorestack(L, funcr); /* previous call may change stack */
253 setobj2s(L, func, tm); /* tag method is the new function to be called */
260 ((L->ci == L->end_ci) ? growCI(L) : \
261 (condhardstacktests(luaD_reallocCI(L, L->size_ci)), ++L->ci))
264 int luaD_precall (lua_State *L, StkId func, int nresults) {
267 if (!ttisfunction(func)) /* `func' is not a function? */
268 func = tryfuncTM(L, func); /* check the `function' tag method */
269 funcr = savestack(L, func);
270 cl = &clvalue(func)->l;
271 L->ci->savedpc = L->savedpc;
272 if (!cl->isC) { /* Lua function? prepare its call */
276 luaD_checkstack(L, p->maxstacksize);
277 func = restorestack(L, funcr);
278 if (!p->is_vararg) { /* no varargs? */
280 if (L->top > base + p->numparams)
281 L->top = base + p->numparams;
283 else { /* vararg function */
284 int nargs = cast_int(L->top - func) - 1;
285 base = adjust_varargs(L, p, nargs);
286 func = restorestack(L, funcr); /* previous call may change the stack */
288 ci = inc_ci(L); /* now `enter' new function */
290 L->base = ci->base = base;
291 ci->top = L->base + p->maxstacksize;
292 lua_assert(ci->top <= L->stack_last);
293 L->savedpc = p->code; /* starting point */
295 ci->nresults = nresults;
296 for (st = L->top; st < ci->top; st++)
299 if (L->hookmask & LUA_MASKCALL) {
300 L->savedpc++; /* hooks assume 'pc' is already incremented */
301 luaD_callhook(L, LUA_HOOKCALL, -1);
302 L->savedpc--; /* correct 'pc' */
306 else { /* if is a C function, call it */
309 luaD_checkstack(L, LUA_MINSTACK); /* ensure minimum stack size */
310 ci = inc_ci(L); /* now `enter' new function */
311 ci->func = restorestack(L, funcr);
312 L->base = ci->base = ci->func + 1;
313 ci->top = L->top + LUA_MINSTACK;
314 lua_assert(ci->top <= L->stack_last);
315 ci->nresults = nresults;
316 if (L->hookmask & LUA_MASKCALL)
317 luaD_callhook(L, LUA_HOOKCALL, -1);
319 n = (*curr_func(L)->c.f)(L); /* do the actual call */
321 if (n < 0) /* yielding? */
324 luaD_poscall(L, L->top - n);
331 static StkId callrethooks (lua_State *L, StkId firstResult) {
332 ptrdiff_t fr = savestack(L, firstResult); /* next call may change stack */
333 luaD_callhook(L, LUA_HOOKRET, -1);
334 if (f_isLua(L->ci)) { /* Lua function? */
335 while ((L->hookmask & LUA_MASKRET) && L->ci->tailcalls--) /* tail calls */
336 luaD_callhook(L, LUA_HOOKTAILRET, -1);
338 return restorestack(L, fr);
342 int luaD_poscall (lua_State *L, StkId firstResult) {
346 if (L->hookmask & LUA_MASKRET)
347 firstResult = callrethooks(L, firstResult);
349 res = ci->func; /* res == final position of 1st result */
350 wanted = ci->nresults;
351 L->base = (ci - 1)->base; /* restore base */
352 L->savedpc = (ci - 1)->savedpc; /* restore savedpc */
353 /* move results to correct place */
354 for (i = wanted; i != 0 && firstResult < L->top; i--)
355 setobjs2s(L, res++, firstResult++);
359 return (wanted - LUA_MULTRET); /* 0 iff wanted == LUA_MULTRET */
364 ** Call a function (C or Lua). The function to be called is at *func.
365 ** The arguments are on the stack, right after the function.
366 ** When returns, all the results are on the stack, starting at the original
367 ** function position.
369 void luaD_call (lua_State *L, StkId func, int nResults) {
370 if (++L->nCcalls >= LUAI_MAXCCALLS) {
371 if (L->nCcalls == LUAI_MAXCCALLS)
372 luaG_runerror(L, "C stack overflow");
373 else if (L->nCcalls >= (LUAI_MAXCCALLS + (LUAI_MAXCCALLS>>3)))
374 luaD_throw(L, LUA_ERRERR); /* error while handing stack error */
376 if (luaD_precall(L, func, nResults) == PCRLUA) /* is a Lua function? */
377 luaV_execute(L, 1); /* call it */
383 static void resume (lua_State *L, void *ud) {
384 StkId firstArg = cast(StkId, ud);
385 CallInfo *ci = L->ci;
386 if (L->status == 0) { /* start coroutine? */
387 lua_assert(ci == L->base_ci && firstArg > L->base);
388 if (luaD_precall(L, firstArg - 1, LUA_MULTRET) != PCRLUA)
391 else { /* resuming from previous yield */
392 lua_assert(L->status == LUA_YIELD);
394 if (!f_isLua(ci)) { /* `common' yield? */
395 /* finish interrupted execution of `OP_CALL' */
396 lua_assert(GET_OPCODE(*((ci-1)->savedpc - 1)) == OP_CALL ||
397 GET_OPCODE(*((ci-1)->savedpc - 1)) == OP_TAILCALL);
398 if (luaD_poscall(L, firstArg)) /* complete it... */
399 L->top = L->ci->top; /* and correct top if not multiple results */
401 else /* yielded inside a hook: just continue its execution */
402 L->base = L->ci->base;
404 luaV_execute(L, cast_int(L->ci - L->base_ci));
408 static int resume_error (lua_State *L, const char *msg) {
409 L->top = L->ci->base;
410 setsvalue2s(L, L->top, luaS_new(L, msg));
417 LUA_API int lua_resume (lua_State *L, int nargs) {
420 if (L->status != LUA_YIELD && (L->status != 0 || L->ci != L->base_ci))
421 return resume_error(L, "cannot resume non-suspended coroutine");
422 if (L->nCcalls >= LUAI_MAXCCALLS)
423 return resume_error(L, "C stack overflow");
424 luai_userstateresume(L, nargs);
425 lua_assert(L->errfunc == 0);
426 L->baseCcalls = ++L->nCcalls;
427 status = luaD_rawrunprotected(L, resume, L->top - nargs);
428 if (status != 0) { /* error? */
429 L->status = cast_byte(status); /* mark thread as `dead' */
430 luaD_seterrorobj(L, status, L->top);
434 lua_assert(L->nCcalls == L->baseCcalls);
443 LUA_API int lua_yield (lua_State *L, int nresults) {
444 luai_userstateyield(L, nresults);
446 if (L->nCcalls > L->baseCcalls)
447 luaG_runerror(L, "attempt to yield across metamethod/C-call boundary");
448 L->base = L->top - nresults; /* protect stack slots below */
449 L->status = LUA_YIELD;
455 int luaD_pcall (lua_State *L, Pfunc func, void *u,
456 ptrdiff_t old_top, ptrdiff_t ef) {
458 unsigned short oldnCcalls = L->nCcalls;
459 ptrdiff_t old_ci = saveci(L, L->ci);
460 lu_byte old_allowhooks = L->allowhook;
461 ptrdiff_t old_errfunc = L->errfunc;
463 status = luaD_rawrunprotected(L, func, u);
464 if (status != 0) { /* an error occurred? */
465 StkId oldtop = restorestack(L, old_top);
466 luaF_close(L, oldtop); /* close eventual pending closures */
467 luaD_seterrorobj(L, status, oldtop);
468 L->nCcalls = oldnCcalls;
469 L->ci = restoreci(L, old_ci);
470 L->base = L->ci->base;
471 L->savedpc = L->ci->savedpc;
472 L->allowhook = old_allowhooks;
473 restore_stack_limit(L);
475 L->errfunc = old_errfunc;
482 ** Execute a protected parser.
484 struct SParser { /* data to `f_parser' */
486 Mbuffer buff; /* buffer to be used by the scanner */
490 static void f_parser (lua_State *L, void *ud) {
494 struct SParser *p = cast(struct SParser *, ud);
495 int c = luaZ_lookahead(p->z);
497 tf = ((c == LUA_SIGNATURE[0]) ? luaU_undump : luaY_parser)(L, p->z,
499 cl = luaF_newLclosure(L, tf->nups, hvalue(gt(L)));
501 for (i = 0; i < tf->nups; i++) /* initialize eventual upvalues */
502 cl->l.upvals[i] = luaF_newupval(L);
503 setclvalue(L, L->top, cl);
508 int luaD_protectedparser (lua_State *L, ZIO *z, const char *name) {
511 p.z = z; p.name = name;
512 luaZ_initbuffer(L, &p.buff);
513 status = luaD_pcall(L, f_parser, &p, savestack(L, L->top), L->errfunc);
514 luaZ_freebuffer(L, &p.buff);