1/*
2** $Id: ldo.c,v 2.38.1.4 2012/01/18 02:27:10 roberto Exp $
3** Stack and Call structure of Lua
4** See Copyright Notice in lua.h
5*/
6
7
8#include <setjmp.h>
9#include <stdlib.h>
10#include <string.h>
11
12#define ldo_c
13#define LUA_CORE
14
15#include "lua.h"
16
17#include "ldebug.h"
18#include "ldo.h"
19#include "lfunc.h"
20#include "lgc.h"
21#include "lmem.h"
22#include "lobject.h"
23#include "lopcodes.h"
24#include "lparser.h"
25#include "lstate.h"
26#include "lstring.h"
27#include "ltable.h"
28#include "ltm.h"
29#include "lundump.h"
30#include "lvm.h"
31#include "lzio.h"
32
33
34
35
36/*
37** {======================================================
38** Error-recovery functions
39** =======================================================
40*/
41
42
43/* chain list of long jump buffers */
44struct lua_longjmp {
45 struct lua_longjmp *previous;
46 luai_jmpbuf b;
47 volatile int status; /* error code */
48};
49
50
51void luaD_seterrorobj (lua_State *L, int errcode, StkId oldtop) {
52 switch (errcode) {
53 case LUA_ERRMEM: {
54 setsvalue2s(L, oldtop, luaS_newliteral(L, MEMERRMSG));
55 break;
56 }
57 case LUA_ERRERR: {
58 setsvalue2s(L, oldtop, luaS_newliteral(L, "error in error handling"));
59 break;
60 }
61 case LUA_ERRSYNTAX:
62 case LUA_ERRRUN: {
63 setobjs2s(L, oldtop, L->top - 1); /* error message on current top */
64 break;
65 }
66 }
67 L->top = oldtop + 1;
68}
69
70
71static 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);
77 }
78}
79
80
81static void resetstack (lua_State *L, int status) {
82 L->ci = L->base_ci;
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;
87 L->allowhook = 1;
88 restore_stack_limit(L);
89 L->errfunc = 0;
90 L->errorJmp = NULL;
91}
92
93
94void luaD_throw (lua_State *L, int errcode) {
95 if (L->errorJmp) {
96 L->errorJmp->status = errcode;
97 LUAI_THROW(L, L->errorJmp);
98 }
99 else {
100 L->status = cast_byte(errcode);
101 if (G(L)->panic) {
102 resetstack(L, errcode);
103 lua_unlock(L);
104 G(L)->panic(L);
105 }
106 exit(EXIT_FAILURE);
107 }
108}
109
110
111int luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud) {
112 struct lua_longjmp lj;
113 lj.status = 0;
114 lj.previous = L->errorJmp; /* chain new error handler */
115 L->errorJmp = &lj;
116 LUAI_TRY(L, &lj,
117 (*f)(L, ud);
118 );
119 L->errorJmp = lj.previous; /* restore old error handler */
120 return lj.status;
121}
122
123/* }====================================================== */
124
125
126static void correctstack (lua_State *L, TValue *oldstack) {
127 CallInfo *ci;
128 GCObject *up;
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;
136 }
137 L->base = (L->base - oldstack) + L->stack;
138}
139
140
141void 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);
149}
150
151
152void 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;
158}
159
160
161void luaD_growstack (lua_State *L, int n) {
162 if (n <= L->stacksize) /* double size is enough? */
163 luaD_reallocstack(L, 2*L->stacksize);
164 else
165 luaD_reallocstack(L, L->stacksize + n);
166}
167
168
169static CallInfo *growCI (lua_State *L) {
170 if (L->size_ci > LUAI_MAXCALLS) /* overflow while handling overflow? */
171 luaD_throw(L, LUA_ERRERR);
172 else {
173 luaD_reallocCI(L, 2*L->size_ci);
174 if (L->size_ci > LUAI_MAXCALLS)
175 luaG_runerror(L, "stack overflow");
176 }
177 return ++L->ci;
178}
179
180
181void 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);
186 lua_Debug ar;
187 ar.event = event;
188 ar.currentline = line;
189 if (event == LUA_HOOKTAILRET)
190 ar.i_ci = 0; /* tail call; no debug information about it */
191 else
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 */
197 lua_unlock(L);
198 (*hook)(L, &ar);
199 lua_lock(L);
200 lua_assert(!L->allowhook);
201 L->allowhook = 1;
202 L->ci->top = restorestack(L, ci_top);
203 L->top = restorestack(L, top);
204 }
205}
206
207
208static StkId adjust_varargs (lua_State *L, Proto *p, int actual) {
209 int i;
210 int nfixargs = p->numparams;
211 Table *htab = NULL;
212 StkId base, fixed;
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);
219 luaC_checkGC(L);
220 luaD_checkstack(L, p->maxstacksize);
221 htab = luaH_new(L, nvar, 1); /* create `arg' table */
222 for (i=0; i<nvar; i++) /* put extra arguments into `arg' table */
223 setobj2n(L, luaH_setnum(L, htab, i+1), L->top - nvar + i);
224 /* store counter in field `n' */
225 setnvalue(luaH_setstr(L, htab, luaS_newliteral(L, "n")), cast_num(nvar));
226 }
227#endif
228 /* move fixed parameters to final position */
229 fixed = L->top - actual; /* first fixed argument */
230 base = L->top; /* final position of first argument */
231 for (i=0; i<nfixargs; i++) {
232 setobjs2s(L, L->top++, fixed+i);
233 setnilvalue(fixed+i);
234 }
235 /* add `arg' parameter */
236 if (htab) {
237 sethvalue(L, L->top++, htab);
238 lua_assert(iswhite(obj2gco(htab)));
239 }
240 return base;
241}
242
243
244static StkId tryfuncTM (lua_State *L, StkId func) {
245 const TValue *tm = luaT_gettmbyobj(L, func, TM_CALL);
246 StkId p;
247 ptrdiff_t funcr = savestack(L, func);
248 if (!ttisfunction(tm))
249 luaG_typeerror(L, func, "call");
250 /* Open a hole inside the stack at `func' */
251 for (p = L->top; p > func; p--) setobjs2s(L, p, p-1);
252 incr_top(L);
253 func = restorestack(L, funcr); /* previous call may change stack */
254 setobj2s(L, func, tm); /* tag method is the new function to be called */
255 return func;
256}
257
258
259
260#define inc_ci(L) \
261 ((L->ci == L->end_ci) ? growCI(L) : \
262 (condhardstacktests(luaD_reallocCI(L, L->size_ci)), ++L->ci))
263
264
265int luaD_precall (lua_State *L, StkId func, int nresults) {
266 LClosure *cl;
267 ptrdiff_t funcr;
268 if (!ttisfunction(func)) /* `func' is not a function? */
269 func = tryfuncTM(L, func); /* check the `function' tag method */
270 funcr = savestack(L, func);
271 cl = &clvalue(func)->l;
272 L->ci->savedpc = L->savedpc;
273 if (!cl->isC) { /* Lua function? prepare its call */
274 CallInfo *ci;
275 StkId st, base;
276 Proto *p = cl->p;
277 luaD_checkstack(L, p->maxstacksize + p->numparams);
278 func = restorestack(L, funcr);
279 if (!p->is_vararg) { /* no varargs? */
280 base = func + 1;
281 if (L->top > base + p->numparams)
282 L->top = base + p->numparams;
283 }
284 else { /* vararg function */
285 int nargs = cast_int(L->top - func) - 1;
286 base = adjust_varargs(L, p, nargs);
287 func = restorestack(L, funcr); /* previous call may change the stack */
288 }
289 ci = inc_ci(L); /* now `enter' new function */
290 ci->func = func;
291 L->base = ci->base = base;
292 ci->top = L->base + p->maxstacksize;
293 lua_assert(ci->top <= L->stack_last);
294 L->savedpc = p->code; /* starting point */
295 ci->tailcalls = 0;
296 ci->nresults = nresults;
297 for (st = L->top; st < ci->top; st++)
298 setnilvalue(st);
299 L->top = ci->top;
300 if (L->hookmask & LUA_MASKCALL) {
301 L->savedpc++; /* hooks assume 'pc' is already incremented */
302 luaD_callhook(L, LUA_HOOKCALL, -1);
303 L->savedpc--; /* correct 'pc' */
304 }
305 return PCRLUA;
306 }
307 else { /* if is a C function, call it */
308 CallInfo *ci;
309 int n;
310 luaD_checkstack(L, LUA_MINSTACK); /* ensure minimum stack size */
311 ci = inc_ci(L); /* now `enter' new function */
312 ci->func = restorestack(L, funcr);
313 L->base = ci->base = ci->func + 1;
314 ci->top = L->top + LUA_MINSTACK;
315 lua_assert(ci->top <= L->stack_last);
316 ci->nresults = nresults;
317 if (L->hookmask & LUA_MASKCALL)
318 luaD_callhook(L, LUA_HOOKCALL, -1);
319 lua_unlock(L);
320 n = (*curr_func(L)->c.f)(L); /* do the actual call */
321 lua_lock(L);
322 if (n < 0) /* yielding? */
323 return PCRYIELD;
324 else {
325 luaD_poscall(L, L->top - n);
326 return PCRC;
327 }
328 }
329}
330
331
332static StkId callrethooks (lua_State *L, StkId firstResult) {
333 ptrdiff_t fr = savestack(L, firstResult); /* next call may change stack */
334 luaD_callhook(L, LUA_HOOKRET, -1);
335 if (f_isLua(L->ci)) { /* Lua function? */
336 while ((L->hookmask & LUA_MASKRET) && L->ci->tailcalls--) /* tail calls */
337 luaD_callhook(L, LUA_HOOKTAILRET, -1);
338 }
339 return restorestack(L, fr);
340}
341
342
343int luaD_poscall (lua_State *L, StkId firstResult) {
344 StkId res;
345 int wanted, i;
346 CallInfo *ci;
347 if (L->hookmask & LUA_MASKRET)
348 firstResult = callrethooks(L, firstResult);
349 ci = L->ci--;
350 res = ci->func; /* res == final position of 1st result */
351 wanted = ci->nresults;
352 L->base = (ci - 1)->base; /* restore base */
353 L->savedpc = (ci - 1)->savedpc; /* restore savedpc */
354 /* move results to correct place */
355 for (i = wanted; i != 0 && firstResult < L->top; i--)
356 setobjs2s(L, res++, firstResult++);
357 while (i-- > 0)
358 setnilvalue(res++);
359 L->top = res;
360 return (wanted - LUA_MULTRET); /* 0 iff wanted == LUA_MULTRET */
361}
362
363
364/*
365** Call a function (C or Lua). The function to be called is at *func.
366** The arguments are on the stack, right after the function.
367** When returns, all the results are on the stack, starting at the original
368** function position.
369*/
370void luaD_call (lua_State *L, StkId func, int nResults) {
371 if (++L->nCcalls >= LUAI_MAXCCALLS) {
372 if (L->nCcalls == LUAI_MAXCCALLS)
373 luaG_runerror(L, "C stack overflow");
374 else if (L->nCcalls >= (LUAI_MAXCCALLS + (LUAI_MAXCCALLS>>3)))
375 luaD_throw(L, LUA_ERRERR); /* error while handing stack error */
376 }
377 if (luaD_precall(L, func, nResults) == PCRLUA) /* is a Lua function? */
378 luaV_execute(L, 1); /* call it */
379 L->nCcalls--;
380 luaC_checkGC(L);
381}
382
383
384static void resume (lua_State *L, void *ud) {
385 StkId firstArg = cast(StkId, ud);
386 CallInfo *ci = L->ci;
387 if (L->status == 0) { /* start coroutine? */
388 lua_assert(ci == L->base_ci && firstArg > L->base);
389 if (luaD_precall(L, firstArg - 1, LUA_MULTRET) != PCRLUA)
390 return;
391 }
392 else { /* resuming from previous yield */
393 lua_assert(L->status == LUA_YIELD);
394 L->status = 0;
395 if (!f_isLua(ci)) { /* `common' yield? */
396 /* finish interrupted execution of `OP_CALL' */
397 lua_assert(GET_OPCODE(*((ci-1)->savedpc - 1)) == OP_CALL ||
398 GET_OPCODE(*((ci-1)->savedpc - 1)) == OP_TAILCALL);
399 if (luaD_poscall(L, firstArg)) /* complete it... */
400 L->top = L->ci->top; /* and correct top if not multiple results */
401 }
402 else /* yielded inside a hook: just continue its execution */
403 L->base = L->ci->base;
404 }
405 luaV_execute(L, cast_int(L->ci - L->base_ci));
406}
407
408
409static int resume_error (lua_State *L, const char *msg) {
410 L->top = L->ci->base;
411 setsvalue2s(L, L->top, luaS_new(L, msg));
412 incr_top(L);
413 lua_unlock(L);
414 return LUA_ERRRUN;
415}
416
417
418LUA_API int lua_resume (lua_State *L, int nargs) {
419 int status;
420 lua_lock(L);
421 if (L->status != LUA_YIELD && (L->status != 0 || L->ci != L->base_ci))
422 return resume_error(L, "cannot resume non-suspended coroutine");
423 if (L->nCcalls >= LUAI_MAXCCALLS)
424 return resume_error(L, "C stack overflow");
425 luai_userstateresume(L, nargs);
426 lua_assert(L->errfunc == 0);
427 L->baseCcalls = ++L->nCcalls;
428 status = luaD_rawrunprotected(L, resume, L->top - nargs);
429 if (status != 0) { /* error? */
430 L->status = cast_byte(status); /* mark thread as `dead' */
431 luaD_seterrorobj(L, status, L->top);
432 L->ci->top = L->top;
433 }
434 else {
435 lua_assert(L->nCcalls == L->baseCcalls);
436 status = L->status;
437 }
438 --L->nCcalls;
439 lua_unlock(L);
440 return status;
441}
442
443
444LUA_API int lua_yield (lua_State *L, int nresults) {
445 luai_userstateyield(L, nresults);
446 lua_lock(L);
447 if (L->nCcalls > L->baseCcalls)
448 luaG_runerror(L, "attempt to yield across metamethod/C-call boundary");
449 L->base = L->top - nresults; /* protect stack slots below */
450 L->status = LUA_YIELD;
451 lua_unlock(L);
452 return -1;
453}
454
455
456int luaD_pcall (lua_State *L, Pfunc func, void *u,
457 ptrdiff_t old_top, ptrdiff_t ef) {
458 int status;
459 unsigned short oldnCcalls = L->nCcalls;
460 ptrdiff_t old_ci = saveci(L, L->ci);
461 lu_byte old_allowhooks = L->allowhook;
462 ptrdiff_t old_errfunc = L->errfunc;
463 L->errfunc = ef;
464 status = luaD_rawrunprotected(L, func, u);
465 if (status != 0) { /* an error occurred? */
466 StkId oldtop = restorestack(L, old_top);
467 luaF_close(L, oldtop); /* close eventual pending closures */
468 luaD_seterrorobj(L, status, oldtop);
469 L->nCcalls = oldnCcalls;
470 L->ci = restoreci(L, old_ci);
471 L->base = L->ci->base;
472 L->savedpc = L->ci->savedpc;
473 L->allowhook = old_allowhooks;
474 restore_stack_limit(L);
475 }
476 L->errfunc = old_errfunc;
477 return status;
478}
479
480
481
482/*
483** Execute a protected parser.
484*/
485struct SParser { /* data to `f_parser' */
486 ZIO *z;
487 Mbuffer buff; /* buffer to be used by the scanner */
488 const char *name;
489};
490
491static void f_parser (lua_State *L, void *ud) {
492 int i;
493 Proto *tf;
494 Closure *cl;
495 struct SParser *p = cast(struct SParser *, ud);
496 luaZ_lookahead(p->z);
497 luaC_checkGC(L);
498 tf = (luaY_parser)(L, p->z,
499 &p->buff, p->name);
500 cl = luaF_newLclosure(L, tf->nups, hvalue(gt(L)));
501 cl->l.p = tf;
502 for (i = 0; i < tf->nups; i++) /* initialize eventual upvalues */
503 cl->l.upvals[i] = luaF_newupval(L);
504 setclvalue(L, L->top, cl);
505 incr_top(L);
506}
507
508
509int luaD_protectedparser (lua_State *L, ZIO *z, const char *name) {
510 struct SParser p;
511 int status;
512 p.z = z; p.name = name;
513 luaZ_initbuffer(L, &p.buff);
514 status = luaD_pcall(L, f_parser, &p, savestack(L, L->top), L->errfunc);
515 luaZ_freebuffer(L, &p.buff);
516 return status;
517}
518
519
520