1 /*
2 ** $Id: ldo.c,v 2.108 2012/10/01 14:05:04 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 "lapi.h"
18 #include "ldebug.h"
19 #include "ldo.h"
20 #include "lfunc.h"
21 #include "lgc.h"
22 #include "lmem.h"
23 #include "lobject.h"
24 #include "lopcodes.h"
25 #include "lparser.h"
26 #include "lstate.h"
27 #include "lstring.h"
28 #include "ltable.h"
29 #include "ltm.h"
30 #include "lundump.h"
31 #include "lvm.h"
32 #include "lzio.h"
33
34
35
36
37 /*
38 ** {======================================================
39 ** Error-recovery functions
40 ** =======================================================
41 */
42
43 /*
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.
48 */
49 #if !defined(LUAI_THROW)
50
51 #if defined(__cplusplus) && !defined(LUA_USE_LONGJMP)
52 /* C++ exceptions */
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 */
57
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
63
64 #else
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
69
70 #endif
71
72 #endif
73
74
75
76 /* chain list of long jump buffers */
77 struct lua_longjmp {
78 struct lua_longjmp *previous;
79 luai_jmpbuf b;
80 volatile int status; /* error code */
81 };
82
83
seterrorobj(lua_State * L,int errcode,StkId oldtop)84 static void seterrorobj (lua_State *L, int errcode, StkId oldtop) {
85 switch (errcode) {
86 case LUA_ERRMEM: { /* memory error? */
87 setsvalue2s(L, oldtop, G(L)->memerrmsg); /* reuse preregistered msg. */
88 break;
89 }
90 case LUA_ERRERR: {
91 setsvalue2s(L, oldtop, luaS_newliteral(L, "error in error handling"));
92 break;
93 }
94 default: {
95 setobjs2s(L, oldtop, L->top - 1); /* error message on current top */
96 break;
97 }
98 }
99 L->top = oldtop + 1;
100 }
101
102
luaD_throw(lua_State * L,int errcode)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 */
107 }
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 */
113 }
114 else { /* no handler at all; abort */
115 if (G(L)->panic) { /* panic function? */
116 lua_unlock(L);
117 G(L)->panic(L); /* call it (last chance to jump out) */
118 }
119 abort();
120 }
121 }
122 }
123
124
luaD_rawrunprotected(lua_State * L,Pfunc f,void * ud)125 int luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud) {
126 unsigned short oldnCcalls = L->nCcalls;
127 struct lua_longjmp lj;
128 lj.status = LUA_OK;
129 lj.previous = L->errorJmp; /* chain new error handler */
130 L->errorJmp = &lj;
131 LUAI_TRY(L, &lj,
132 (*f)(L, ud);
133 );
134 L->errorJmp = lj.previous; /* restore old error handler */
135 L->nCcalls = oldnCcalls;
136 return lj.status;
137 }
138
139 /* }====================================================== */
140
141
correctstack(lua_State * L,TValue * oldstack)142 static void correctstack (lua_State *L, TValue *oldstack) {
143 CallInfo *ci;
144 GCObject *up;
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;
151 if (isLua(ci))
152 ci->u.l.base = (ci->u.l.base - oldstack) + L->stack;
153 }
154 }
155
156
157 /* some space for error handling */
158 #define ERRORSTACKSIZE (LUAI_MAXSTACK + 200)
159
160
luaD_reallocstack(lua_State * L,int newsize)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);
172 }
173
174
luaD_growstack(lua_State * L,int n)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);
179 else {
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");
187 }
188 else
189 luaD_reallocstack(L, newsize);
190 }
191 }
192
193
stackinuse(lua_State * L)194 static int stackinuse (lua_State *L) {
195 CallInfo *ci;
196 StkId lim = L->top;
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;
200 }
201 return cast_int(lim - L->stack) + 1; /* part of stack in use */
202 }
203
204
luaD_shrinkstack(lua_State * L)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) */
212 else
213 luaD_reallocstack(L, goodsize); /* shrink it */
214 }
215
216
luaD_hook(lua_State * L,int event,int line)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);
223 lua_Debug ar;
224 ar.event = event;
225 ar.currentline = line;
226 ar.i_ci = ci;
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;
232 lua_unlock(L);
233 (*hook)(L, &ar);
234 lua_lock(L);
235 lua_assert(!L->allowhook);
236 L->allowhook = 1;
237 ci->top = restorestack(L, ci_top);
238 L->top = restorestack(L, top);
239 ci->callstatus &= ~CIST_HOOKED;
240 }
241 }
242
243
callhook(lua_State * L,CallInfo * ci)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;
251 }
252 luaD_hook(L, hook, -1);
253 ci->u.l.savedpc--; /* correct 'pc' */
254 }
255
256
adjust_varargs(lua_State * L,Proto * p,int actual)257 static StkId adjust_varargs (lua_State *L, Proto *p, int actual) {
258 int i;
259 int nfixargs = p->numparams;
260 StkId base, fixed;
261 lua_assert(actual >= nfixargs);
262 /* move fixed parameters to final position */
263 fixed = L->top - actual; /* first fixed argument */
264 base = L->top; /* final position of first argument */
265 for (i=0; i<nfixargs; i++) {
266 setobjs2s(L, L->top++, fixed + i);
267 setnilvalue(fixed + i);
268 }
269 return base;
270 }
271
272
tryfuncTM(lua_State * L,StkId func)273 static StkId tryfuncTM (lua_State *L, StkId func) {
274 const TValue *tm = luaT_gettmbyobj(L, func, TM_CALL);
275 StkId p;
276 ptrdiff_t funcr = savestack(L, func);
277 if (!ttisfunction(tm))
278 luaG_typeerror(L, func, "call");
279 /* Open a hole inside the stack at `func' */
280 for (p = L->top; p > func; p--) setobjs2s(L, p, p-1);
281 incr_top(L);
282 func = restorestack(L, funcr); /* previous call may change stack */
283 setobj2s(L, func, tm); /* tag method is the new function to be called */
284 return func;
285 }
286
287
288
289 #define next_ci(L) (L->ci = (L->ci->next ? L->ci->next : luaE_extendCI(L)))
290
291
292 /*
293 ** returns true if function has been executed (C function)
294 */
luaD_precall(lua_State * L,StkId func,int nresults)295 int luaD_precall (lua_State *L, StkId func, int nresults) {
296 lua_CFunction f;
297 CallInfo *ci;
298 int n; /* number of arguments (Lua) or returns (C) */
299 ptrdiff_t funcr = savestack(L, func);
300 switch (ttype(func)) {
301 case LUA_TLCF: /* light C function */
302 f = fvalue(func);
303 goto Cfunc;
304 case LUA_TCCL: { /* C closure */
305 f = clCvalue(func)->f;
306 Cfunc:
307 luaD_checkstack(L, LUA_MINSTACK); /* ensure minimum stack size */
308 ci = next_ci(L); /* now 'enter' new function */
309 ci->nresults = nresults;
310 ci->func = restorestack(L, funcr);
311 ci->top = L->top + LUA_MINSTACK;
312 lua_assert(ci->top <= L->stack_last);
313 ci->callstatus = 0;
314 luaC_checkGC(L); /* stack grow uses memory */
315 if (L->hookmask & LUA_MASKCALL)
316 luaD_hook(L, LUA_HOOKCALL, -1);
317 lua_unlock(L);
318 n = (*f)(L); /* do the actual call */
319 lua_lock(L);
320 api_checknelems(L, n);
321 luaD_poscall(L, L->top - n);
322 return 1;
323 }
324 case LUA_TLCL: { /* Lua function: prepare its call */
325 StkId base;
326 Proto *p = clLvalue(func)->p;
327 luaD_checkstack(L, p->maxstacksize);
328 func = restorestack(L, funcr);
329 n = cast_int(L->top - func) - 1; /* number of real arguments */
330 for (; n < p->numparams; n++)
331 setnilvalue(L->top++); /* complete missing arguments */
332 base = (!p->is_vararg) ? func + 1 : adjust_varargs(L, p, n);
333 ci = next_ci(L); /* now 'enter' new function */
334 ci->nresults = nresults;
335 ci->func = func;
336 ci->u.l.base = base;
337 ci->top = base + p->maxstacksize;
338 lua_assert(ci->top <= L->stack_last);
339 ci->u.l.savedpc = p->code; /* starting point */
340 ci->callstatus = CIST_LUA;
341 L->top = ci->top;
342 luaC_checkGC(L); /* stack grow uses memory */
343 if (L->hookmask & LUA_MASKCALL)
344 callhook(L, ci);
345 return 0;
346 }
347 default: { /* not a function */
348 func = tryfuncTM(L, func); /* retry with 'function' tag method */
349 return luaD_precall(L, func, nresults); /* now it must be a function */
350 }
351 }
352 }
353
354
luaD_poscall(lua_State * L,StkId firstResult)355 int luaD_poscall (lua_State *L, StkId firstResult) {
356 StkId res;
357 int wanted, i;
358 CallInfo *ci = L->ci;
359 if (L->hookmask & (LUA_MASKRET | LUA_MASKLINE)) {
360 if (L->hookmask & LUA_MASKRET) {
361 ptrdiff_t fr = savestack(L, firstResult); /* hook may change stack */
362 luaD_hook(L, LUA_HOOKRET, -1);
363 firstResult = restorestack(L, fr);
364 }
365 L->oldpc = ci->previous->u.l.savedpc; /* 'oldpc' for caller function */
366 }
367 res = ci->func; /* res == final position of 1st result */
368 wanted = ci->nresults;
369 L->ci = ci = ci->previous; /* back to caller */
370 /* move results to correct place */
371 for (i = wanted; i != 0 && firstResult < L->top; i--)
372 setobjs2s(L, res++, firstResult++);
373 while (i-- > 0)
374 setnilvalue(res++);
375 L->top = res;
376 return (wanted - LUA_MULTRET); /* 0 iff wanted == LUA_MULTRET */
377 }
378
379
380 /*
381 ** Call a function (C or Lua). The function to be called is at *func.
382 ** The arguments are on the stack, right after the function.
383 ** When returns, all the results are on the stack, starting at the original
384 ** function position.
385 */
luaD_call(lua_State * L,StkId func,int nResults,int allowyield)386 void luaD_call (lua_State *L, StkId func, int nResults, int allowyield) {
387 if (++L->nCcalls >= LUAI_MAXCCALLS) {
388 if (L->nCcalls == LUAI_MAXCCALLS)
389 luaG_runerror(L, "C stack overflow");
390 else if (L->nCcalls >= (LUAI_MAXCCALLS + (LUAI_MAXCCALLS>>3)))
391 luaD_throw(L, LUA_ERRERR); /* error while handing stack error */
392 }
393 if (!allowyield) L->nny++;
394 if (!luaD_precall(L, func, nResults)) /* is a Lua function? */
395 luaV_execute(L); /* call it */
396 if (!allowyield) L->nny--;
397 L->nCcalls--;
398 }
399
400
finishCcall(lua_State * L)401 static void finishCcall (lua_State *L) {
402 CallInfo *ci = L->ci;
403 int n;
404 lua_assert(ci->u.c.k != NULL); /* must have a continuation */
405 lua_assert(L->nny == 0);
406 if (ci->callstatus & CIST_YPCALL) { /* was inside a pcall? */
407 ci->callstatus &= ~CIST_YPCALL; /* finish 'lua_pcall' */
408 L->errfunc = ci->u.c.old_errfunc;
409 }
410 /* finish 'lua_callk'/'lua_pcall' */
411 adjustresults(L, ci->nresults);
412 /* call continuation function */
413 if (!(ci->callstatus & CIST_STAT)) /* no call status? */
414 ci->u.c.status = LUA_YIELD; /* 'default' status */
415 lua_assert(ci->u.c.status != LUA_OK);
416 ci->callstatus = (ci->callstatus & ~(CIST_YPCALL | CIST_STAT)) | CIST_YIELDED;
417 lua_unlock(L);
418 n = (*ci->u.c.k)(L);
419 lua_lock(L);
420 api_checknelems(L, n);
421 /* finish 'luaD_precall' */
422 luaD_poscall(L, L->top - n);
423 }
424
425
unroll(lua_State * L,void * ud)426 static void unroll (lua_State *L, void *ud) {
427 UNUSED(ud);
428 for (;;) {
429 if (L->ci == &L->base_ci) /* stack is empty? */
430 return; /* coroutine finished normally */
431 if (!isLua(L->ci)) /* C function? */
432 finishCcall(L);
433 else { /* Lua function */
434 luaV_finishOp(L); /* finish interrupted instruction */
435 luaV_execute(L); /* execute down to higher C 'boundary' */
436 }
437 }
438 }
439
440
441 /*
442 ** check whether thread has a suspended protected call
443 */
findpcall(lua_State * L)444 static CallInfo *findpcall (lua_State *L) {
445 CallInfo *ci;
446 for (ci = L->ci; ci != NULL; ci = ci->previous) { /* search for a pcall */
447 if (ci->callstatus & CIST_YPCALL)
448 return ci;
449 }
450 return NULL; /* no pending pcall */
451 }
452
453
recover(lua_State * L,int status)454 static int recover (lua_State *L, int status) {
455 StkId oldtop;
456 CallInfo *ci = findpcall(L);
457 if (ci == NULL) return 0; /* no recovery point */
458 /* "finish" luaD_pcall */
459 oldtop = restorestack(L, ci->extra);
460 luaF_close(L, oldtop);
461 seterrorobj(L, status, oldtop);
462 L->ci = ci;
463 L->allowhook = ci->u.c.old_allowhook;
464 L->nny = 0; /* should be zero to be yieldable */
465 luaD_shrinkstack(L);
466 L->errfunc = ci->u.c.old_errfunc;
467 ci->callstatus |= CIST_STAT; /* call has error status */
468 ci->u.c.status = status; /* (here it is) */
469 return 1; /* continue running the coroutine */
470 }
471
472
473 /*
474 ** signal an error in the call to 'resume', not in the execution of the
475 ** coroutine itself. (Such errors should not be handled by any coroutine
476 ** error handler and should not kill the coroutine.)
477 */
resume_error(lua_State * L,const char * msg,StkId firstArg)478 static l_noret resume_error (lua_State *L, const char *msg, StkId firstArg) {
479 L->top = firstArg; /* remove args from the stack */
480 setsvalue2s(L, L->top, luaS_new(L, msg)); /* push error message */
481 api_incr_top(L);
482 luaD_throw(L, -1); /* jump back to 'lua_resume' */
483 }
484
485
486 /*
487 ** do the work for 'lua_resume' in protected mode
488 */
resume(lua_State * L,void * ud)489 static void resume (lua_State *L, void *ud) {
490 int nCcalls = L->nCcalls;
491 StkId firstArg = cast(StkId, ud);
492 CallInfo *ci = L->ci;
493 if (nCcalls >= LUAI_MAXCCALLS)
494 resume_error(L, "C stack overflow", firstArg);
495 if (L->status == LUA_OK) { /* may be starting a coroutine */
496 if (ci != &L->base_ci) /* not in base level? */
497 resume_error(L, "cannot resume non-suspended coroutine", firstArg);
498 /* coroutine is in base level; start running it */
499 if (!luaD_precall(L, firstArg - 1, LUA_MULTRET)) /* Lua function? */
500 luaV_execute(L); /* call it */
501 }
502 else if (L->status != LUA_YIELD)
503 resume_error(L, "cannot resume dead coroutine", firstArg);
504 else { /* resuming from previous yield */
505 L->status = LUA_OK;
506 ci->func = restorestack(L, ci->extra);
507 if (isLua(ci)) /* yielded inside a hook? */
508 luaV_execute(L); /* just continue running Lua code */
509 else { /* 'common' yield */
510 if (ci->u.c.k != NULL) { /* does it have a continuation? */
511 int n;
512 ci->u.c.status = LUA_YIELD; /* 'default' status */
513 ci->callstatus |= CIST_YIELDED;
514 lua_unlock(L);
515 n = (*ci->u.c.k)(L); /* call continuation */
516 lua_lock(L);
517 api_checknelems(L, n);
518 firstArg = L->top - n; /* yield results come from continuation */
519 }
520 luaD_poscall(L, firstArg); /* finish 'luaD_precall' */
521 }
522 unroll(L, NULL);
523 }
524 lua_assert(nCcalls == L->nCcalls);
525 }
526
527
lua_resume(lua_State * L,lua_State * from,int nargs)528 LUA_API int lua_resume (lua_State *L, lua_State *from, int nargs) {
529 int status;
530 lua_lock(L);
531 luai_userstateresume(L, nargs);
532 L->nCcalls = (from) ? from->nCcalls + 1 : 1;
533 L->nny = 0; /* allow yields */
534 api_checknelems(L, (L->status == LUA_OK) ? nargs + 1 : nargs);
535 status = luaD_rawrunprotected(L, resume, L->top - nargs);
536 if (status == -1) /* error calling 'lua_resume'? */
537 status = LUA_ERRRUN;
538 else { /* yield or regular error */
539 while (status != LUA_OK && status != LUA_YIELD) { /* error? */
540 if (recover(L, status)) /* recover point? */
541 status = luaD_rawrunprotected(L, unroll, NULL); /* run continuation */
542 else { /* unrecoverable error */
543 L->status = cast_byte(status); /* mark thread as `dead' */
544 seterrorobj(L, status, L->top);
545 L->ci->top = L->top;
546 break;
547 }
548 }
549 lua_assert(status == L->status);
550 }
551 L->nny = 1; /* do not allow yields */
552 L->nCcalls--;
553 lua_assert(L->nCcalls == ((from) ? from->nCcalls : 0));
554 lua_unlock(L);
555 return status;
556 }
557
558
lua_yieldk(lua_State * L,int nresults,int ctx,lua_CFunction k)559 LUA_API int lua_yieldk (lua_State *L, int nresults, int ctx, lua_CFunction k) {
560 CallInfo *ci = L->ci;
561 luai_userstateyield(L, nresults);
562 lua_lock(L);
563 api_checknelems(L, nresults);
564 if (L->nny > 0) {
565 if (L != G(L)->mainthread)
566 luaG_runerror(L, "attempt to yield across a C-call boundary");
567 else
568 luaG_runerror(L, "attempt to yield from outside a coroutine");
569 }
570 L->status = LUA_YIELD;
571 ci->extra = savestack(L, ci->func); /* save current 'func' */
572 if (isLua(ci)) { /* inside a hook? */
573 api_check(L, k == NULL, "hooks cannot continue after yielding");
574 }
575 else {
576 if ((ci->u.c.k = k) != NULL) /* is there a continuation? */
577 ci->u.c.ctx = ctx; /* save context */
578 ci->func = L->top - nresults - 1; /* protect stack below results */
579 luaD_throw(L, LUA_YIELD);
580 }
581 lua_assert(ci->callstatus & CIST_HOOKED); /* must be inside a hook */
582 lua_unlock(L);
583 return 0; /* return to 'luaD_hook' */
584 }
585
586
luaD_pcall(lua_State * L,Pfunc func,void * u,ptrdiff_t old_top,ptrdiff_t ef)587 int luaD_pcall (lua_State *L, Pfunc func, void *u,
588 ptrdiff_t old_top, ptrdiff_t ef) {
589 int status;
590 CallInfo *old_ci = L->ci;
591 lu_byte old_allowhooks = L->allowhook;
592 unsigned short old_nny = L->nny;
593 ptrdiff_t old_errfunc = L->errfunc;
594 L->errfunc = ef;
595 status = luaD_rawrunprotected(L, func, u);
596 if (status != LUA_OK) { /* an error occurred? */
597 StkId oldtop = restorestack(L, old_top);
598 luaF_close(L, oldtop); /* close possible pending closures */
599 seterrorobj(L, status, oldtop);
600 L->ci = old_ci;
601 L->allowhook = old_allowhooks;
602 L->nny = old_nny;
603 luaD_shrinkstack(L);
604 }
605 L->errfunc = old_errfunc;
606 return status;
607 }
608
609
610
611 /*
612 ** Execute a protected parser.
613 */
614 struct SParser { /* data to `f_parser' */
615 ZIO *z;
616 Mbuffer buff; /* dynamic structure used by the scanner */
617 Dyndata dyd; /* dynamic structures used by the parser */
618 const char *mode;
619 const char *name;
620 };
621
622
checkmode(lua_State * L,const char * mode,const char * x)623 static void checkmode (lua_State *L, const char *mode, const char *x) {
624 if (mode && strchr(mode, x[0]) == NULL) {
625 luaO_pushfstring(L,
626 "attempt to load a %s chunk (mode is " LUA_QS ")", x, mode);
627 luaD_throw(L, LUA_ERRSYNTAX);
628 }
629 }
630
631
f_parser(lua_State * L,void * ud)632 static void f_parser (lua_State *L, void *ud) {
633 int i;
634 Closure *cl;
635 struct SParser *p = cast(struct SParser *, ud);
636 int c = zgetc(p->z); /* read first character */
637 if (c == LUA_SIGNATURE[0]) {
638 checkmode(L, p->mode, "binary");
639 cl = luaU_undump(L, p->z, &p->buff, p->name);
640 }
641 else {
642 checkmode(L, p->mode, "text");
643 cl = luaY_parser(L, p->z, &p->buff, &p->dyd, p->name, c);
644 }
645 lua_assert(cl->l.nupvalues == cl->l.p->sizeupvalues);
646 for (i = 0; i < cl->l.nupvalues; i++) { /* initialize upvalues */
647 UpVal *up = luaF_newupval(L);
648 cl->l.upvals[i] = up;
649 luaC_objbarrier(L, cl, up);
650 }
651 }
652
653
luaD_protectedparser(lua_State * L,ZIO * z,const char * name,const char * mode)654 int luaD_protectedparser (lua_State *L, ZIO *z, const char *name,
655 const char *mode) {
656 struct SParser p;
657 int status;
658 L->nny++; /* cannot yield during parsing */
659 p.z = z; p.name = name; p.mode = mode;
660 p.dyd.actvar.arr = NULL; p.dyd.actvar.size = 0;
661 p.dyd.gt.arr = NULL; p.dyd.gt.size = 0;
662 p.dyd.label.arr = NULL; p.dyd.label.size = 0;
663 luaZ_initbuffer(L, &p.buff);
664 status = luaD_pcall(L, f_parser, &p, savestack(L, L->top), L->errfunc);
665 luaZ_freebuffer(L, &p.buff);
666 luaM_freearray(L, p.dyd.actvar.arr, p.dyd.actvar.size);
667 luaM_freearray(L, p.dyd.gt.arr, p.dyd.gt.size);
668 luaM_freearray(L, p.dyd.label.arr, p.dyd.label.size);
669 L->nny--;
670 return status;
671 }
672
673
674