1/*
2** $Id: ldo.c,v 2.157.1.1 2017/04/19 17:20:42 roberto Exp $
3** Stack and Call structure of Lua
4** See Copyright Notice in lua.h
5*/
6
7#define ldo_c
8#define LUA_CORE
9
10#include "lprefix.h"
11
12
13#include <setjmp.h>
14#include <stdlib.h>
15#include <string.h>
16
17#include "lua.h"
18
19#include "lapi.h"
20#include "ldebug.h"
21#include "ldo.h"
22#include "lfunc.h"
23#include "lgc.h"
24#include "lmem.h"
25#include "lobject.h"
26#include "lopcodes.h"
27#include "lparser.h"
28#include "lstate.h"
29#include "lstring.h"
30#include "ltable.h"
31#include "ltm.h"
32#include "lundump.h"
33#include "lvm.h"
34#include "lzio.h"
35
36
37
38#define errorstatus(s) ((s) > LUA_YIELD)
39
40
41/*
42** {======================================================
43** Error-recovery functions
44** =======================================================
45*/
46
47/*
48** LUAI_THROW/LUAI_TRY define how Lua does exception handling. By
49** default, Lua handles errors with exceptions when compiling as
50** C++ code, with _longjmp/_setjmp when asked to use them, and with
51** longjmp/setjmp otherwise.
52*/
53#if !defined(LUAI_THROW) /* { */
54
55#if defined(__cplusplus) && !defined(LUA_USE_LONGJMP) /* { */
56
57/* C++ exceptions */
58#define LUAI_THROW(L,c) throw(c)
59#define LUAI_TRY(L,c,a) \
60 try { a } catch(...) { if ((c)->status == 0) (c)->status = -1; }
61#define luai_jmpbuf int /* dummy variable */
62
63#elif defined(LUA_USE_POSIX) /* }{ */
64
65/* in POSIX, try _longjmp/_setjmp (more efficient) */
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#else /* }{ */
71
72/* ISO C handling with long jumps */
73#define LUAI_THROW(L,c) longjmp((c)->b, 1)
74#define LUAI_TRY(L,c,a) if (setjmp((c)->b) == 0) { a }
75#define luai_jmpbuf jmp_buf
76
77#endif /* } */
78
79#endif /* } */
80
81
82
83/* chain list of long jump buffers */
84struct lua_longjmp {
85 struct lua_longjmp *previous;
86 luai_jmpbuf b;
87 volatile int status; /* error code */
88};
89
90
91static void seterrorobj (lua_State *L, int errcode, StkId oldtop) {
92 switch (errcode) {
93 case LUA_ERRMEM: { /* memory error? */
94 setsvalue2s(L, oldtop, G(L)->memerrmsg); /* reuse preregistered msg. */
95 break;
96 }
97 case LUA_ERRERR: {
98 setsvalue2s(L, oldtop, luaS_newliteral(L, "error in error handling"));
99 break;
100 }
101 default: {
102 setobjs2s(L, oldtop, L->top - 1); /* error message on current top */
103 break;
104 }
105 }
106 L->top = oldtop + 1;
107}
108
109
110l_noret luaD_throw (lua_State *L, int errcode) {
111 if (L->errorJmp) { /* thread has an error handler? */
112 L->errorJmp->status = errcode; /* set status */
113 LUAI_THROW(L, L->errorJmp); /* jump to it */
114 }
115 else { /* thread has no error handler */
116 global_State *g = G(L);
117 L->status = cast_byte(errcode); /* mark it as dead */
118 if (g->mainthread->errorJmp) { /* main thread has a handler? */
119 setobjs2s(L, g->mainthread->top++, L->top - 1); /* copy error obj. */
120 luaD_throw(g->mainthread, errcode); /* re-throw in main thread */
121 }
122 else { /* no handler at all; abort */
123 if (g->panic) { /* panic function? */
124 seterrorobj(L, errcode, L->top); /* assume EXTRA_STACK */
125 if (L->ci->top < L->top)
126 L->ci->top = L->top; /* pushing msg. can break this invariant */
127 lua_unlock(L);
128 g->panic(L); /* call panic function (last chance to jump out) */
129 }
130 abort();
131 }
132 }
133}
134
135
136int luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud) {
137 unsigned short oldnCcalls = L->nCcalls;
138 struct lua_longjmp lj;
139 lj.status = LUA_OK;
140 lj.previous = L->errorJmp; /* chain new error handler */
141 L->errorJmp = &lj;
142 LUAI_TRY(L, &lj,
143 (*f)(L, ud);
144 );
145 L->errorJmp = lj.previous; /* restore old error handler */
146 L->nCcalls = oldnCcalls;
147 return lj.status;
148}
149
150/* }====================================================== */
151
152
153/*
154** {==================================================================
155** Stack reallocation
156** ===================================================================
157*/
158static void correctstack (lua_State *L, TValue *oldstack) {
159 CallInfo *ci;
160 UpVal *up;
161 L->top = (L->top - oldstack) + L->stack;
162 for (up = L->openupval; up != NULL; up = up->u.open.next)
163 up->v = (up->v - oldstack) + L->stack;
164 for (ci = L->ci; ci != NULL; ci = ci->previous) {
165 ci->top = (ci->top - oldstack) + L->stack;
166 ci->func = (ci->func - oldstack) + L->stack;
167 if (isLua(ci))
168 ci->u.l.base = (ci->u.l.base - oldstack) + L->stack;
169 }
170}
171
172
173/* some space for error handling */
174#define ERRORSTACKSIZE (LUAI_MAXSTACK + 200)
175
176
177void luaD_reallocstack (lua_State *L, int newsize) {
178 TValue *oldstack = L->stack;
179 int lim = L->stacksize;
180 lua_assert(newsize <= LUAI_MAXSTACK || newsize == ERRORSTACKSIZE);
181 lua_assert(L->stack_last - L->stack == L->stacksize - EXTRA_STACK);
182 luaM_reallocvector(L, L->stack, L->stacksize, newsize, TValue);
183 for (; lim < newsize; lim++)
184 setnilvalue(L->stack + lim); /* erase new segment */
185 L->stacksize = newsize;
186 L->stack_last = L->stack + newsize - EXTRA_STACK;
187 correctstack(L, oldstack);
188}
189
190
191void luaD_growstack (lua_State *L, int n) {
192 int size = L->stacksize;
193 if (size > LUAI_MAXSTACK) /* error after extra size? */
194 luaD_throw(L, LUA_ERRERR);
195 else {
196 int needed = cast_int(L->top - L->stack) + n + EXTRA_STACK;
197 int newsize = 2 * size;
198 if (newsize > LUAI_MAXSTACK) newsize = LUAI_MAXSTACK;
199 if (newsize < needed) newsize = needed;
200 if (newsize > LUAI_MAXSTACK) { /* stack overflow? */
201 luaD_reallocstack(L, ERRORSTACKSIZE);
202 luaG_runerror(L, "stack overflow");
203 }
204 else
205 luaD_reallocstack(L, newsize);
206 }
207}
208
209
210static int stackinuse (lua_State *L) {
211 CallInfo *ci;
212 StkId lim = L->top;
213 for (ci = L->ci; ci != NULL; ci = ci->previous) {
214 if (lim < ci->top) lim = ci->top;
215 }
216 lua_assert(lim <= L->stack_last);
217 return cast_int(lim - L->stack) + 1; /* part of stack in use */
218}
219
220
221void luaD_shrinkstack (lua_State *L) {
222 int inuse = stackinuse(L);
223 int goodsize = inuse + (inuse / 8) + 2*EXTRA_STACK;
224 if (goodsize > LUAI_MAXSTACK)
225 goodsize = LUAI_MAXSTACK; /* respect stack limit */
226 if (L->stacksize > LUAI_MAXSTACK) /* had been handling stack overflow? */
227 luaE_freeCI(L); /* free all CIs (list grew because of an error) */
228 else
229 luaE_shrinkCI(L); /* shrink list */
230 /* if thread is currently not handling a stack overflow and its
231 good size is smaller than current size, shrink its stack */
232 if (inuse <= (LUAI_MAXSTACK - EXTRA_STACK) &&
233 goodsize < L->stacksize)
234 luaD_reallocstack(L, goodsize);
235 else /* don't change stack */
236 condmovestack(L,{},{}); /* (change only for debugging) */
237}
238
239
240void luaD_inctop (lua_State *L) {
241 luaD_checkstack(L, 1);
242 L->top++;
243}
244
245/* }================================================================== */
246
247
248/*
249** Call a hook for the given event. Make sure there is a hook to be
250** called. (Both 'L->hook' and 'L->hookmask', which triggers this
251** function, can be changed asynchronously by signals.)
252*/
253void luaD_hook (lua_State *L, int event, int line) {
254 lua_Hook hook = L->hook;
255 if (hook && L->allowhook) { /* make sure there is a hook */
256 CallInfo *ci = L->ci;
257 ptrdiff_t top = savestack(L, L->top);
258 ptrdiff_t ci_top = savestack(L, ci->top);
259 lua_Debug ar;
260 ar.event = event;
261 ar.currentline = line;
262 ar.i_ci = ci;
263 luaD_checkstack(L, LUA_MINSTACK); /* ensure minimum stack size */
264 ci->top = L->top + LUA_MINSTACK;
265 lua_assert(ci->top <= L->stack_last);
266 L->allowhook = 0; /* cannot call hooks inside a hook */
267 ci->callstatus |= CIST_HOOKED;
268 lua_unlock(L);
269 (*hook)(L, &ar);
270 lua_lock(L);
271 lua_assert(!L->allowhook);
272 L->allowhook = 1;
273 ci->top = restorestack(L, ci_top);
274 L->top = restorestack(L, top);
275 ci->callstatus &= ~CIST_HOOKED;
276 }
277}
278
279
280static void callhook (lua_State *L, CallInfo *ci) {
281 int hook = LUA_HOOKCALL;
282 ci->u.l.savedpc++; /* hooks assume 'pc' is already incremented */
283 if (isLua(ci->previous) &&
284 GET_OPCODE(*(ci->previous->u.l.savedpc - 1)) == OP_TAILCALL) {
285 ci->callstatus |= CIST_TAIL;
286 hook = LUA_HOOKTAILCALL;
287 }
288 luaD_hook(L, hook, -1);
289 ci->u.l.savedpc--; /* correct 'pc' */
290}
291
292
293static StkId adjust_varargs (lua_State *L, Proto *p, int actual) {
294 int i;
295 int nfixargs = p->numparams;
296 StkId base, fixed;
297 /* move fixed parameters to final position */
298 fixed = L->top - actual; /* first fixed argument */
299 base = L->top; /* final position of first argument */
300 for (i = 0; i < nfixargs && i < actual; i++) {
301 setobjs2s(L, L->top++, fixed + i);
302 setnilvalue(fixed + i); /* erase original copy (for GC) */
303 }
304 for (; i < nfixargs; i++)
305 setnilvalue(L->top++); /* complete missing arguments */
306 return base;
307}
308
309
310/*
311** Check whether __call metafield of 'func' is a function. If so, put
312** it in stack below original 'func' so that 'luaD_precall' can call
313** it. Raise an error if __call metafield is not a function.
314*/
315static void tryfuncTM (lua_State *L, StkId func) {
316 const TValue *tm = luaT_gettmbyobj(L, func, TM_CALL);
317 StkId p;
318 if (!ttisfunction(tm))
319 luaG_typeerror(L, func, "call");
320 /* Open a hole inside the stack at 'func' */
321 for (p = L->top; p > func; p--)
322 setobjs2s(L, p, p-1);
323 L->top++; /* slot ensured by caller */
324 setobj2s(L, func, tm); /* tag method is the new function to be called */
325}
326
327
328/*
329** Given 'nres' results at 'firstResult', move 'wanted' of them to 'res'.
330** Handle most typical cases (zero results for commands, one result for
331** expressions, multiple results for tail calls/single parameters)
332** separated.
333*/
334static int moveresults (lua_State *L, const TValue *firstResult, StkId res,
335 int nres, int wanted) {
336 switch (wanted) { /* handle typical cases separately */
337 case 0: break; /* nothing to move */
338 case 1: { /* one result needed */
339 if (nres == 0) /* no results? */
340 firstResult = luaO_nilobject; /* adjust with nil */
341 setobjs2s(L, res, firstResult); /* move it to proper place */
342 break;
343 }
344 case LUA_MULTRET: {
345 int i;
346 for (i = 0; i < nres; i++) /* move all results to correct place */
347 setobjs2s(L, res + i, firstResult + i);
348 L->top = res + nres;
349 return 0; /* wanted == LUA_MULTRET */
350 }
351 default: {
352 int i;
353 if (wanted <= nres) { /* enough results? */
354 for (i = 0; i < wanted; i++) /* move wanted results to correct place */
355 setobjs2s(L, res + i, firstResult + i);
356 }
357 else { /* not enough results; use all of them plus nils */
358 for (i = 0; i < nres; i++) /* move all results to correct place */
359 setobjs2s(L, res + i, firstResult + i);
360 for (; i < wanted; i++) /* complete wanted number of results */
361 setnilvalue(res + i);
362 }
363 break;
364 }
365 }
366 L->top = res + wanted; /* top points after the last result */
367 return 1;
368}
369
370
371/*
372** Finishes a function call: calls hook if necessary, removes CallInfo,
373** moves current number of results to proper place; returns 0 iff call
374** wanted multiple (variable number of) results.
375*/
376int luaD_poscall (lua_State *L, CallInfo *ci, StkId firstResult, int nres) {
377 StkId res;
378 int wanted = ci->nresults;
379 if (L->hookmask & (LUA_MASKRET | LUA_MASKLINE)) {
380 if (L->hookmask & LUA_MASKRET) {
381 ptrdiff_t fr = savestack(L, firstResult); /* hook may change stack */
382 luaD_hook(L, LUA_HOOKRET, -1);
383 firstResult = restorestack(L, fr);
384 }
385 L->oldpc = ci->previous->u.l.savedpc; /* 'oldpc' for caller function */
386 }
387 res = ci->func; /* res == final position of 1st result */
388 L->ci = ci->previous; /* back to caller */
389 /* move results to proper place */
390 return moveresults(L, firstResult, res, nres, wanted);
391}
392
393
394
395#define next_ci(L) (L->ci = (L->ci->next ? L->ci->next : luaE_extendCI(L)))
396
397
398/* macro to check stack size, preserving 'p' */
399#define checkstackp(L,n,p) \
400 luaD_checkstackaux(L, n, \
401 ptrdiff_t t__ = savestack(L, p); /* save 'p' */ \
402 luaC_checkGC(L), /* stack grow uses memory */ \
403 p = restorestack(L, t__)) /* 'pos' part: restore 'p' */
404
405
406/*
407** Prepares a function call: checks the stack, creates a new CallInfo
408** entry, fills in the relevant information, calls hook if needed.
409** If function is a C function, does the call, too. (Otherwise, leave
410** the execution ('luaV_execute') to the caller, to allow stackless
411** calls.) Returns true iff function has been executed (C function).
412*/
413int luaD_precall (lua_State *L, StkId func, int nresults) {
414 lua_CFunction f;
415 CallInfo *ci;
416 switch (ttype(func)) {
417 case LUA_TCCL: /* C closure */
418 f = clCvalue(func)->f;
419 goto Cfunc;
420 case LUA_TLCF: /* light C function */
421 f = fvalue(func);
422 Cfunc: {
423 int n; /* number of returns */
424 checkstackp(L, LUA_MINSTACK, func); /* ensure minimum stack size */
425 ci = next_ci(L); /* now 'enter' new function */
426 ci->nresults = nresults;
427 ci->func = func;
428 ci->top = L->top + LUA_MINSTACK;
429 lua_assert(ci->top <= L->stack_last);
430 ci->callstatus = 0;
431 if (L->hookmask & LUA_MASKCALL)
432 luaD_hook(L, LUA_HOOKCALL, -1);
433 lua_unlock(L);
434 n = (*f)(L); /* do the actual call */
435 lua_lock(L);
436 api_checknelems(L, n);
437 luaD_poscall(L, ci, L->top - n, n);
438 return 1;
439 }
440 case LUA_TLCL: { /* Lua function: prepare its call */
441 StkId base;
442 Proto *p = clLvalue(func)->p;
443 int n = cast_int(L->top - func) - 1; /* number of real arguments */
444 int fsize = p->maxstacksize; /* frame size */
445 checkstackp(L, fsize, func);
446 if (p->is_vararg)
447 base = adjust_varargs(L, p, n);
448 else { /* non vararg function */
449 for (; n < p->numparams; n++)
450 setnilvalue(L->top++); /* complete missing arguments */
451 base = func + 1;
452 }
453 ci = next_ci(L); /* now 'enter' new function */
454 ci->nresults = nresults;
455 ci->func = func;
456 ci->u.l.base = base;
457 L->top = ci->top = base + fsize;
458 lua_assert(ci->top <= L->stack_last);
459 ci->u.l.savedpc = p->code; /* starting point */
460 ci->callstatus = CIST_LUA;
461 if (L->hookmask & LUA_MASKCALL)
462 callhook(L, ci);
463 return 0;
464 }
465 default: { /* not a function */
466 checkstackp(L, 1, func); /* ensure space for metamethod */
467 tryfuncTM(L, func); /* try to get '__call' metamethod */
468 return luaD_precall(L, func, nresults); /* now it must be a function */
469 }
470 }
471}
472
473
474/*
475** Check appropriate error for stack overflow ("regular" overflow or
476** overflow while handling stack overflow). If 'nCalls' is larger than
477** LUAI_MAXCCALLS (which means it is handling a "regular" overflow) but
478** smaller than 9/8 of LUAI_MAXCCALLS, does not report an error (to
479** allow overflow handling to work)
480*/
481static void stackerror (lua_State *L) {
482 if (L->nCcalls == LUAI_MAXCCALLS)
483 luaG_runerror(L, "C stack overflow");
484 else if (L->nCcalls >= (LUAI_MAXCCALLS + (LUAI_MAXCCALLS>>3)))
485 luaD_throw(L, LUA_ERRERR); /* error while handing stack error */
486}
487
488
489/*
490** Call a function (C or Lua). The function to be called is at *func.
491** The arguments are on the stack, right after the function.
492** When returns, all the results are on the stack, starting at the original
493** function position.
494*/
495void luaD_call (lua_State *L, StkId func, int nResults) {
496 if (++L->nCcalls >= LUAI_MAXCCALLS)
497 stackerror(L);
498 if (!luaD_precall(L, func, nResults)) /* is a Lua function? */
499 luaV_execute(L); /* call it */
500 L->nCcalls--;
501}
502
503
504/*
505** Similar to 'luaD_call', but does not allow yields during the call
506*/
507void luaD_callnoyield (lua_State *L, StkId func, int nResults) {
508 L->nny++;
509 luaD_call(L, func, nResults);
510 L->nny--;
511}
512
513
514/*
515** Completes the execution of an interrupted C function, calling its
516** continuation function.
517*/
518static void finishCcall (lua_State *L, int status) {
519 CallInfo *ci = L->ci;
520 int n;
521 /* must have a continuation and must be able to call it */
522 lua_assert(ci->u.c.k != NULL && L->nny == 0);
523 /* error status can only happen in a protected call */
524 lua_assert((ci->callstatus & CIST_YPCALL) || status == LUA_YIELD);
525 if (ci->callstatus & CIST_YPCALL) { /* was inside a pcall? */
526 ci->callstatus &= ~CIST_YPCALL; /* continuation is also inside it */
527 L->errfunc = ci->u.c.old_errfunc; /* with the same error function */
528 }
529 /* finish 'lua_callk'/'lua_pcall'; CIST_YPCALL and 'errfunc' already
530 handled */
531 adjustresults(L, ci->nresults);
532 lua_unlock(L);
533 n = (*ci->u.c.k)(L, status, ci->u.c.ctx); /* call continuation function */
534 lua_lock(L);
535 api_checknelems(L, n);
536 luaD_poscall(L, ci, L->top - n, n); /* finish 'luaD_precall' */
537}
538
539
540/*
541** Executes "full continuation" (everything in the stack) of a
542** previously interrupted coroutine until the stack is empty (or another
543** interruption long-jumps out of the loop). If the coroutine is
544** recovering from an error, 'ud' points to the error status, which must
545** be passed to the first continuation function (otherwise the default
546** status is LUA_YIELD).
547*/
548static void unroll (lua_State *L, void *ud) {
549 if (ud != NULL) /* error status? */
550 finishCcall(L, *(int *)ud); /* finish 'lua_pcallk' callee */
551 while (L->ci != &L->base_ci) { /* something in the stack */
552 if (!isLua(L->ci)) /* C function? */
553 finishCcall(L, LUA_YIELD); /* complete its execution */
554 else { /* Lua function */
555 luaV_finishOp(L); /* finish interrupted instruction */
556 luaV_execute(L); /* execute down to higher C 'boundary' */
557 }
558 }
559}
560
561
562/*
563** Try to find a suspended protected call (a "recover point") for the
564** given thread.
565*/
566static CallInfo *findpcall (lua_State *L) {
567 CallInfo *ci;
568 for (ci = L->ci; ci != NULL; ci = ci->previous) { /* search for a pcall */
569 if (ci->callstatus & CIST_YPCALL)
570 return ci;
571 }
572 return NULL; /* no pending pcall */
573}
574
575
576/*
577** Recovers from an error in a coroutine. Finds a recover point (if
578** there is one) and completes the execution of the interrupted
579** 'luaD_pcall'. If there is no recover point, returns zero.
580*/
581static int recover (lua_State *L, int status) {
582 StkId oldtop;
583 CallInfo *ci = findpcall(L);
584 if (ci == NULL) return 0; /* no recovery point */
585 /* "finish" luaD_pcall */
586 oldtop = restorestack(L, ci->extra);
587 luaF_close(L, oldtop);
588 seterrorobj(L, status, oldtop);
589 L->ci = ci;
590 L->allowhook = getoah(ci->callstatus); /* restore original 'allowhook' */
591 L->nny = 0; /* should be zero to be yieldable */
592 luaD_shrinkstack(L);
593 L->errfunc = ci->u.c.old_errfunc;
594 return 1; /* continue running the coroutine */
595}
596
597
598/*
599** Signal an error in the call to 'lua_resume', not in the execution
600** of the coroutine itself. (Such errors should not be handled by any
601** coroutine error handler and should not kill the coroutine.)
602*/
603static int resume_error (lua_State *L, const char *msg, int narg) {
604 L->top -= narg; /* remove args from the stack */
605 setsvalue2s(L, L->top, luaS_new(L, msg)); /* push error message */
606 api_incr_top(L);
607 lua_unlock(L);
608 return LUA_ERRRUN;
609}
610
611
612/*
613** Do the work for 'lua_resume' in protected mode. Most of the work
614** depends on the status of the coroutine: initial state, suspended
615** inside a hook, or regularly suspended (optionally with a continuation
616** function), plus erroneous cases: non-suspended coroutine or dead
617** coroutine.
618*/
619static void resume (lua_State *L, void *ud) {
620 int n = *(cast(int*, ud)); /* number of arguments */
621 StkId firstArg = L->top - n; /* first argument */
622 CallInfo *ci = L->ci;
623 if (L->status == LUA_OK) { /* starting a coroutine? */
624 if (!luaD_precall(L, firstArg - 1, LUA_MULTRET)) /* Lua function? */
625 luaV_execute(L); /* call it */
626 }
627 else { /* resuming from previous yield */
628 lua_assert(L->status == LUA_YIELD);
629 L->status = LUA_OK; /* mark that it is running (again) */
630 ci->func = restorestack(L, ci->extra);
631 if (isLua(ci)) /* yielded inside a hook? */
632 luaV_execute(L); /* just continue running Lua code */
633 else { /* 'common' yield */
634 if (ci->u.c.k != NULL) { /* does it have a continuation function? */
635 lua_unlock(L);
636 n = (*ci->u.c.k)(L, LUA_YIELD, ci->u.c.ctx); /* call continuation */
637 lua_lock(L);
638 api_checknelems(L, n);
639 firstArg = L->top - n; /* yield results come from continuation */
640 }
641 luaD_poscall(L, ci, firstArg, n); /* finish 'luaD_precall' */
642 }
643 unroll(L, NULL); /* run continuation */
644 }
645}
646
647
648LUA_API int lua_resume (lua_State *L, lua_State *from, int nargs) {
649 int status;
650 unsigned short oldnny = L->nny; /* save "number of non-yieldable" calls */
651 lua_lock(L);
652 if (L->status == LUA_OK) { /* may be starting a coroutine */
653 if (L->ci != &L->base_ci) /* not in base level? */
654 return resume_error(L, "cannot resume non-suspended coroutine", nargs);
655 }
656 else if (L->status != LUA_YIELD)
657 return resume_error(L, "cannot resume dead coroutine", nargs);
658 L->nCcalls = (from) ? from->nCcalls + 1 : 1;
659 if (L->nCcalls >= LUAI_MAXCCALLS)
660 return resume_error(L, "C stack overflow", nargs);
661 luai_userstateresume(L, nargs);
662 L->nny = 0; /* allow yields */
663 api_checknelems(L, (L->status == LUA_OK) ? nargs + 1 : nargs);
664 status = luaD_rawrunprotected(L, resume, &nargs);
665 if (status == -1) /* error calling 'lua_resume'? */
666 status = LUA_ERRRUN;
667 else { /* continue running after recoverable errors */
668 while (errorstatus(status) && recover(L, status)) {
669 /* unroll continuation */
670 status = luaD_rawrunprotected(L, unroll, &status);
671 }
672 if (errorstatus(status)) { /* unrecoverable error? */
673 L->status = cast_byte(status); /* mark thread as 'dead' */
674 seterrorobj(L, status, L->top); /* push error message */
675 L->ci->top = L->top;
676 }
677 else lua_assert(status == L->status); /* normal end or yield */
678 }
679 L->nny = oldnny; /* restore 'nny' */
680 L->nCcalls--;
681 lua_assert(L->nCcalls == ((from) ? from->nCcalls : 0));
682 lua_unlock(L);
683 return status;
684}
685
686
687LUA_API int lua_isyieldable (lua_State *L) {
688 return (L->nny == 0);
689}
690
691
692LUA_API int lua_yieldk (lua_State *L, int nresults, lua_KContext ctx,
693 lua_KFunction k) {
694 CallInfo *ci = L->ci;
695 luai_userstateyield(L, nresults);
696 lua_lock(L);
697 api_checknelems(L, nresults);
698 if (L->nny > 0) {
699 if (L != G(L)->mainthread)
700 luaG_runerror(L, "attempt to yield across a C-call boundary");
701 else
702 luaG_runerror(L, "attempt to yield from outside a coroutine");
703 }
704 L->status = LUA_YIELD;
705 ci->extra = savestack(L, ci->func); /* save current 'func' */
706 if (isLua(ci)) { /* inside a hook? */
707 api_check(L, k == NULL, "hooks cannot continue after yielding");
708 }
709 else {
710 if ((ci->u.c.k = k) != NULL) /* is there a continuation? */
711 ci->u.c.ctx = ctx; /* save context */
712 ci->func = L->top - nresults - 1; /* protect stack below results */
713 luaD_throw(L, LUA_YIELD);
714 }
715 lua_assert(ci->callstatus & CIST_HOOKED); /* must be inside a hook */
716 lua_unlock(L);
717 return 0; /* return to 'luaD_hook' */
718}
719
720
721int luaD_pcall (lua_State *L, Pfunc func, void *u,
722 ptrdiff_t old_top, ptrdiff_t ef) {
723 int status;
724 CallInfo *old_ci = L->ci;
725 lu_byte old_allowhooks = L->allowhook;
726 unsigned short old_nny = L->nny;
727 ptrdiff_t old_errfunc = L->errfunc;
728 L->errfunc = ef;
729 status = luaD_rawrunprotected(L, func, u);
730 if (status != LUA_OK) { /* an error occurred? */
731 StkId oldtop = restorestack(L, old_top);
732 luaF_close(L, oldtop); /* close possible pending closures */
733 seterrorobj(L, status, oldtop);
734 L->ci = old_ci;
735 L->allowhook = old_allowhooks;
736 L->nny = old_nny;
737 luaD_shrinkstack(L);
738 }
739 L->errfunc = old_errfunc;
740 return status;
741}
742
743
744
745/*
746** Execute a protected parser.
747*/
748struct SParser { /* data to 'f_parser' */
749 ZIO *z;
750 Mbuffer buff; /* dynamic structure used by the scanner */
751 Dyndata dyd; /* dynamic structures used by the parser */
752 const char *mode;
753 const char *name;
754};
755
756
757static void checkmode (lua_State *L, const char *mode, const char *x) {
758 if (mode && strchr(mode, x[0]) == NULL) {
759 luaO_pushfstring(L,
760 "attempt to load a %s chunk (mode is '%s')", x, mode);
761 luaD_throw(L, LUA_ERRSYNTAX);
762 }
763}
764
765
766static void f_parser (lua_State *L, void *ud) {
767 LClosure *cl;
768 struct SParser *p = cast(struct SParser *, ud);
769 int c = zgetc(p->z); /* read first character */
770 if (c == LUA_SIGNATURE[0]) {
771 checkmode(L, p->mode, "binary");
772 cl = luaU_undump(L, p->z, p->name);
773 }
774 else {
775 checkmode(L, p->mode, "text");
776 cl = luaY_parser(L, p->z, &p->buff, &p->dyd, p->name, c);
777 }
778 lua_assert(cl->nupvalues == cl->p->sizeupvalues);
779 luaF_initupvals(L, cl);
780}
781
782
783int luaD_protectedparser (lua_State *L, ZIO *z, const char *name,
784 const char *mode) {
785 struct SParser p;
786 int status;
787 L->nny++; /* cannot yield during parsing */
788 p.z = z; p.name = name; p.mode = mode;
789 p.dyd.actvar.arr = NULL; p.dyd.actvar.size = 0;
790 p.dyd.gt.arr = NULL; p.dyd.gt.size = 0;
791 p.dyd.label.arr = NULL; p.dyd.label.size = 0;
792 luaZ_initbuffer(L, &p.buff);
793 status = luaD_pcall(L, f_parser, &p, savestack(L, L->top), L->errfunc);
794 luaZ_freebuffer(L, &p.buff);
795 luaM_freearray(L, p.dyd.actvar.arr, p.dyd.actvar.size);
796 luaM_freearray(L, p.dyd.gt.arr, p.dyd.gt.size);
797 luaM_freearray(L, p.dyd.label.arr, p.dyd.label.size);
798 L->nny--;
799 return status;
800}
801
802
803