1/*
2** $Id: ldo.c $
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
91void luaD_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 case CLOSEPROTECT: {
102 setnilvalue(s2v(oldtop)); /* no error message */
103 break;
104 }
105 default: {
106 setobjs2s(L, oldtop, L->top - 1); /* error message on current top */
107 break;
108 }
109 }
110 L->top = oldtop + 1;
111}
112
113
114l_noret luaD_throw (lua_State *L, int errcode) {
115 if (L->errorJmp) { /* thread has an error handler? */
116 L->errorJmp->status = errcode; /* set status */
117 LUAI_THROW(L, L->errorJmp); /* jump to it */
118 }
119 else { /* thread has no error handler */
120 global_State *g = G(L);
121 errcode = luaF_close(L, L->stack, errcode); /* close all upvalues */
122 L->status = cast_byte(errcode); /* mark it as dead */
123 if (g->mainthread->errorJmp) { /* main thread has a handler? */
124 setobjs2s(L, g->mainthread->top++, L->top - 1); /* copy error obj. */
125 luaD_throw(g->mainthread, errcode); /* re-throw in main thread */
126 }
127 else { /* no handler at all; abort */
128 if (g->panic) { /* panic function? */
129 luaD_seterrorobj(L, errcode, L->top); /* assume EXTRA_STACK */
130 if (L->ci->top < L->top)
131 L->ci->top = L->top; /* pushing msg. can break this invariant */
132 lua_unlock(L);
133 g->panic(L); /* call panic function (last chance to jump out) */
134 }
135 abort();
136 }
137 }
138}
139
140
141int luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud) {
142 l_uint32 oldnCcalls = L->nCcalls;
143 struct lua_longjmp lj;
144 lj.status = LUA_OK;
145 lj.previous = L->errorJmp; /* chain new error handler */
146 L->errorJmp = &lj;
147 LUAI_TRY(L, &lj,
148 (*f)(L, ud);
149 );
150 L->errorJmp = lj.previous; /* restore old error handler */
151 L->nCcalls = oldnCcalls;
152 return lj.status;
153}
154
155/* }====================================================== */
156
157
158/*
159** {==================================================================
160** Stack reallocation
161** ===================================================================
162*/
163static void correctstack (lua_State *L, StkId oldstack, StkId newstack) {
164 CallInfo *ci;
165 UpVal *up;
166 if (oldstack == newstack)
167 return; /* stack address did not change */
168 L->top = (L->top - oldstack) + newstack;
169 for (up = L->openupval; up != NULL; up = up->u.open.next)
170 up->v = s2v((uplevel(up) - oldstack) + newstack);
171 for (ci = L->ci; ci != NULL; ci = ci->previous) {
172 ci->top = (ci->top - oldstack) + newstack;
173 ci->func = (ci->func - oldstack) + newstack;
174 if (isLua(ci))
175 ci->u.l.trap = 1; /* signal to update 'trap' in 'luaV_execute' */
176 }
177}
178
179
180/* some space for error handling */
181#define ERRORSTACKSIZE (LUAI_MAXSTACK + 200)
182
183
184int luaD_reallocstack (lua_State *L, int newsize, int raiseerror) {
185 int lim = stacksize(L);
186 StkId newstack = luaM_reallocvector(L, L->stack,
187 lim + EXTRA_STACK, newsize + EXTRA_STACK, StackValue);
188 lua_assert(newsize <= LUAI_MAXSTACK || newsize == ERRORSTACKSIZE);
189 if (unlikely(newstack == NULL)) { /* reallocation failed? */
190 if (raiseerror)
191 luaM_error(L);
192 else return 0; /* do not raise an error */
193 }
194 for (; lim < newsize; lim++)
195 setnilvalue(s2v(newstack + lim)); /* erase new segment */
196 correctstack(L, L->stack, newstack);
197 L->stack = newstack;
198 L->stack_last = L->stack + newsize;
199 return 1;
200}
201
202
203/*
204** Try to grow the stack by at least 'n' elements. when 'raiseerror'
205** is true, raises any error; otherwise, return 0 in case of errors.
206*/
207int luaD_growstack (lua_State *L, int n, int raiseerror) {
208 int size = stacksize(L);
209 if (unlikely(size > LUAI_MAXSTACK)) {
210 /* if stack is larger than maximum, thread is already using the
211 extra space reserved for errors, that is, thread is handling
212 a stack error; cannot grow further than that. */
213 lua_assert(stacksize(L) == ERRORSTACKSIZE);
214 if (raiseerror)
215 luaD_throw(L, LUA_ERRERR); /* error inside message handler */
216 return 0; /* if not 'raiseerror', just signal it */
217 }
218 else {
219 int newsize = 2 * size; /* tentative new size */
220 int needed = cast_int(L->top - L->stack) + n;
221 if (newsize > LUAI_MAXSTACK) /* cannot cross the limit */
222 newsize = LUAI_MAXSTACK;
223 if (newsize < needed) /* but must respect what was asked for */
224 newsize = needed;
225 if (likely(newsize <= LUAI_MAXSTACK))
226 return luaD_reallocstack(L, newsize, raiseerror);
227 else { /* stack overflow */
228 /* add extra size to be able to handle the error message */
229 luaD_reallocstack(L, ERRORSTACKSIZE, raiseerror);
230 if (raiseerror)
231 luaG_runerror(L, "stack overflow");
232 return 0;
233 }
234 }
235}
236
237
238static int stackinuse (lua_State *L) {
239 CallInfo *ci;
240 int res;
241 StkId lim = L->top;
242 for (ci = L->ci; ci != NULL; ci = ci->previous) {
243 if (lim < ci->top) lim = ci->top;
244 }
245 lua_assert(lim <= L->stack_last);
246 res = cast_int(lim - L->stack) + 1; /* part of stack in use */
247 if (res < LUA_MINSTACK)
248 res = LUA_MINSTACK; /* ensure a minimum size */
249 return res;
250}
251
252
253/*
254** If stack size is more than 3 times the current use, reduce that size
255** to twice the current use. (So, the final stack size is at most 2/3 the
256** previous size, and half of its entries are empty.)
257** As a particular case, if stack was handling a stack overflow and now
258** it is not, 'max' (limited by LUAI_MAXSTACK) will be smaller than
259** stacksize (equal to ERRORSTACKSIZE in this case), and so the stack
260** will be reduced to a "regular" size.
261*/
262void luaD_shrinkstack (lua_State *L) {
263 int inuse = stackinuse(L);
264 int nsize = inuse * 2; /* proposed new size */
265 int max = inuse * 3; /* maximum "reasonable" size */
266 if (max > LUAI_MAXSTACK) {
267 max = LUAI_MAXSTACK; /* respect stack limit */
268 if (nsize > LUAI_MAXSTACK)
269 nsize = LUAI_MAXSTACK;
270 }
271 /* if thread is currently not handling a stack overflow and its
272 size is larger than maximum "reasonable" size, shrink it */
273 if (inuse <= LUAI_MAXSTACK && stacksize(L) > max)
274 luaD_reallocstack(L, nsize, 0); /* ok if that fails */
275 else /* don't change stack */
276 condmovestack(L,{},{}); /* (change only for debugging) */
277 luaE_shrinkCI(L); /* shrink CI list */
278}
279
280
281void luaD_inctop (lua_State *L) {
282 luaD_checkstack(L, 1);
283 L->top++;
284}
285
286/* }================================================================== */
287
288
289/*
290** Call a hook for the given event. Make sure there is a hook to be
291** called. (Both 'L->hook' and 'L->hookmask', which trigger this
292** function, can be changed asynchronously by signals.)
293*/
294void luaD_hook (lua_State *L, int event, int line,
295 int ftransfer, int ntransfer) {
296 lua_Hook hook = L->hook;
297 if (hook && L->allowhook) { /* make sure there is a hook */
298 int mask = CIST_HOOKED;
299 CallInfo *ci = L->ci;
300 ptrdiff_t top = savestack(L, L->top);
301 ptrdiff_t ci_top = savestack(L, ci->top);
302 lua_Debug ar;
303 ar.event = event;
304 ar.currentline = line;
305 ar.i_ci = ci;
306 if (ntransfer != 0) {
307 mask |= CIST_TRAN; /* 'ci' has transfer information */
308 ci->u2.transferinfo.ftransfer = ftransfer;
309 ci->u2.transferinfo.ntransfer = ntransfer;
310 }
311 luaD_checkstack(L, LUA_MINSTACK); /* ensure minimum stack size */
312 if (L->top + LUA_MINSTACK > ci->top)
313 ci->top = L->top + LUA_MINSTACK;
314 L->allowhook = 0; /* cannot call hooks inside a hook */
315 ci->callstatus |= mask;
316 lua_unlock(L);
317 (*hook)(L, &ar);
318 lua_lock(L);
319 lua_assert(!L->allowhook);
320 L->allowhook = 1;
321 ci->top = restorestack(L, ci_top);
322 L->top = restorestack(L, top);
323 ci->callstatus &= ~mask;
324 }
325}
326
327
328/*
329** Executes a call hook for Lua functions. This function is called
330** whenever 'hookmask' is not zero, so it checks whether call hooks are
331** active.
332*/
333void luaD_hookcall (lua_State *L, CallInfo *ci) {
334 int hook = (ci->callstatus & CIST_TAIL) ? LUA_HOOKTAILCALL : LUA_HOOKCALL;
335 Proto *p;
336 if (!(L->hookmask & LUA_MASKCALL)) /* some other hook? */
337 return; /* don't call hook */
338 p = clLvalue(s2v(ci->func))->p;
339 L->top = ci->top; /* prepare top */
340 ci->u.l.savedpc++; /* hooks assume 'pc' is already incremented */
341 luaD_hook(L, hook, -1, 1, p->numparams);
342 ci->u.l.savedpc--; /* correct 'pc' */
343}
344
345
346static StkId rethook (lua_State *L, CallInfo *ci, StkId firstres, int nres) {
347 ptrdiff_t oldtop = savestack(L, L->top); /* hook may change top */
348 int delta = 0;
349 if (isLuacode(ci)) {
350 Proto *p = ci_func(ci)->p;
351 if (p->is_vararg)
352 delta = ci->u.l.nextraargs + p->numparams + 1;
353 if (L->top < ci->top)
354 L->top = ci->top; /* correct top to run hook */
355 }
356 if (L->hookmask & LUA_MASKRET) { /* is return hook on? */
357 int ftransfer;
358 ci->func += delta; /* if vararg, back to virtual 'func' */
359 ftransfer = cast(unsigned short, firstres - ci->func);
360 luaD_hook(L, LUA_HOOKRET, -1, ftransfer, nres); /* call it */
361 ci->func -= delta;
362 }
363 if (isLua(ci = ci->previous))
364 L->oldpc = pcRel(ci->u.l.savedpc, ci_func(ci)->p); /* update 'oldpc' */
365 return restorestack(L, oldtop);
366}
367
368
369/*
370** Check whether 'func' has a '__call' metafield. If so, put it in the
371** stack, below original 'func', so that 'luaD_precall' can call it. Raise
372** an error if there is no '__call' metafield.
373*/
374void luaD_tryfuncTM (lua_State *L, StkId func) {
375 const TValue *tm = luaT_gettmbyobj(L, s2v(func), TM_CALL);
376 StkId p;
377 if (unlikely(ttisnil(tm)))
378 luaG_typeerror(L, s2v(func), "call"); /* nothing to call */
379 for (p = L->top; p > func; p--) /* open space for metamethod */
380 setobjs2s(L, p, p-1);
381 L->top++; /* stack space pre-allocated by the caller */
382 setobj2s(L, func, tm); /* metamethod is the new function to be called */
383}
384
385
386/*
387** Given 'nres' results at 'firstResult', move 'wanted' of them to 'res'.
388** Handle most typical cases (zero results for commands, one result for
389** expressions, multiple results for tail calls/single parameters)
390** separated.
391*/
392static void moveresults (lua_State *L, StkId res, int nres, int wanted) {
393 StkId firstresult;
394 int i;
395 switch (wanted) { /* handle typical cases separately */
396 case 0: /* no values needed */
397 L->top = res;
398 return;
399 case 1: /* one value needed */
400 if (nres == 0) /* no results? */
401 setnilvalue(s2v(res)); /* adjust with nil */
402 else
403 setobjs2s(L, res, L->top - nres); /* move it to proper place */
404 L->top = res + 1;
405 return;
406 case LUA_MULTRET:
407 wanted = nres; /* we want all results */
408 break;
409 default: /* multiple results (or to-be-closed variables) */
410 if (hastocloseCfunc(wanted)) { /* to-be-closed variables? */
411 ptrdiff_t savedres = savestack(L, res);
412 luaF_close(L, res, LUA_OK); /* may change the stack */
413 res = restorestack(L, savedres);
414 wanted = codeNresults(wanted); /* correct value */
415 if (wanted == LUA_MULTRET)
416 wanted = nres;
417 }
418 break;
419 }
420 firstresult = L->top - nres; /* index of first result */
421 /* move all results to correct place */
422 for (i = 0; i < nres && i < wanted; i++)
423 setobjs2s(L, res + i, firstresult + i);
424 for (; i < wanted; i++) /* complete wanted number of results */
425 setnilvalue(s2v(res + i));
426 L->top = res + wanted; /* top points after the last result */
427}
428
429
430/*
431** Finishes a function call: calls hook if necessary, removes CallInfo,
432** moves current number of results to proper place.
433*/
434void luaD_poscall (lua_State *L, CallInfo *ci, int nres) {
435 if (L->hookmask)
436 L->top = rethook(L, ci, L->top - nres, nres);
437 L->ci = ci->previous; /* back to caller */
438 /* move results to proper place */
439 moveresults(L, ci->func, nres, ci->nresults);
440}
441
442
443
444#define next_ci(L) (L->ci->next ? L->ci->next : luaE_extendCI(L))
445
446
447/*
448** Prepare a function for a tail call, building its call info on top
449** of the current call info. 'narg1' is the number of arguments plus 1
450** (so that it includes the function itself).
451*/
452void luaD_pretailcall (lua_State *L, CallInfo *ci, StkId func, int narg1) {
453 Proto *p = clLvalue(s2v(func))->p;
454 int fsize = p->maxstacksize; /* frame size */
455 int nfixparams = p->numparams;
456 int i;
457 for (i = 0; i < narg1; i++) /* move down function and arguments */
458 setobjs2s(L, ci->func + i, func + i);
459 checkstackGC(L, fsize);
460 func = ci->func; /* moved-down function */
461 for (; narg1 <= nfixparams; narg1++)
462 setnilvalue(s2v(func + narg1)); /* complete missing arguments */
463 ci->top = func + 1 + fsize; /* top for new function */
464 lua_assert(ci->top <= L->stack_last);
465 ci->u.l.savedpc = p->code; /* starting point */
466 ci->callstatus |= CIST_TAIL;
467 L->top = func + narg1; /* set top */
468}
469
470
471/*
472** Prepares the call to a function (C or Lua). For C functions, also do
473** the call. The function to be called is at '*func'. The arguments
474** are on the stack, right after the function. Returns the CallInfo
475** to be executed, if it was a Lua function. Otherwise (a C function)
476** returns NULL, with all the results on the stack, starting at the
477** original function position.
478*/
479CallInfo *luaD_precall (lua_State *L, StkId func, int nresults) {
480 lua_CFunction f;
481 retry:
482 switch (ttypetag(s2v(func))) {
483 case LUA_VCCL: /* C closure */
484 f = clCvalue(s2v(func))->f;
485 goto Cfunc;
486 case LUA_VLCF: /* light C function */
487 f = fvalue(s2v(func));
488 Cfunc: {
489 int n; /* number of returns */
490 CallInfo *ci;
491 checkstackGCp(L, LUA_MINSTACK, func); /* ensure minimum stack size */
492 L->ci = ci = next_ci(L);
493 ci->nresults = nresults;
494 ci->callstatus = CIST_C;
495 ci->top = L->top + LUA_MINSTACK;
496 ci->func = func;
497 lua_assert(ci->top <= L->stack_last);
498 if (L->hookmask & LUA_MASKCALL) {
499 int narg = cast_int(L->top - func) - 1;
500 luaD_hook(L, LUA_HOOKCALL, -1, 1, narg);
501 }
502 lua_unlock(L);
503 n = (*f)(L); /* do the actual call */
504 lua_lock(L);
505 api_checknelems(L, n);
506 luaD_poscall(L, ci, n);
507 return NULL;
508 }
509 case LUA_VLCL: { /* Lua function */
510 CallInfo *ci;
511 Proto *p = clLvalue(s2v(func))->p;
512 int narg = cast_int(L->top - func) - 1; /* number of real arguments */
513 int nfixparams = p->numparams;
514 int fsize = p->maxstacksize; /* frame size */
515 checkstackGCp(L, fsize, func);
516 L->ci = ci = next_ci(L);
517 ci->nresults = nresults;
518 ci->u.l.savedpc = p->code; /* starting point */
519 ci->top = func + 1 + fsize;
520 ci->func = func;
521 L->ci = ci;
522 for (; narg < nfixparams; narg++)
523 setnilvalue(s2v(L->top++)); /* complete missing arguments */
524 lua_assert(ci->top <= L->stack_last);
525 return ci;
526 }
527 default: { /* not a function */
528 checkstackGCp(L, 1, func); /* space for metamethod */
529 luaD_tryfuncTM(L, func); /* try to get '__call' metamethod */
530 goto retry; /* try again with metamethod */
531 }
532 }
533}
534
535
536/*
537** Call a function (C or Lua). 'inc' can be 1 (increment number
538** of recursive invocations in the C stack) or nyci (the same plus
539** increment number of non-yieldable calls).
540*/
541static void docall (lua_State *L, StkId func, int nResults, int inc) {
542 CallInfo *ci;
543 L->nCcalls += inc;
544 if (unlikely(getCcalls(L) >= LUAI_MAXCCALLS))
545 luaE_checkcstack(L);
546 if ((ci = luaD_precall(L, func, nResults)) != NULL) { /* Lua function? */
547 ci->callstatus = CIST_FRESH; /* mark that it is a "fresh" execute */
548 luaV_execute(L, ci); /* call it */
549 }
550 L->nCcalls -= inc;
551}
552
553
554/*
555** External interface for 'docall'
556*/
557void luaD_call (lua_State *L, StkId func, int nResults) {
558 return docall(L, func, nResults, 1);
559}
560
561
562/*
563** Similar to 'luaD_call', but does not allow yields during the call.
564*/
565void luaD_callnoyield (lua_State *L, StkId func, int nResults) {
566 return docall(L, func, nResults, nyci);
567}
568
569
570/*
571** Completes the execution of an interrupted C function, calling its
572** continuation function.
573*/
574static void finishCcall (lua_State *L, int status) {
575 CallInfo *ci = L->ci;
576 int n;
577 /* must have a continuation and must be able to call it */
578 lua_assert(ci->u.c.k != NULL && yieldable(L));
579 /* error status can only happen in a protected call */
580 lua_assert((ci->callstatus & CIST_YPCALL) || status == LUA_YIELD);
581 if (ci->callstatus & CIST_YPCALL) { /* was inside a pcall? */
582 ci->callstatus &= ~CIST_YPCALL; /* continuation is also inside it */
583 L->errfunc = ci->u.c.old_errfunc; /* with the same error function */
584 }
585 /* finish 'lua_callk'/'lua_pcall'; CIST_YPCALL and 'errfunc' already
586 handled */
587 adjustresults(L, ci->nresults);
588 lua_unlock(L);
589 n = (*ci->u.c.k)(L, status, ci->u.c.ctx); /* call continuation function */
590 lua_lock(L);
591 api_checknelems(L, n);
592 luaD_poscall(L, ci, n); /* finish 'luaD_call' */
593}
594
595
596/*
597** Executes "full continuation" (everything in the stack) of a
598** previously interrupted coroutine until the stack is empty (or another
599** interruption long-jumps out of the loop). If the coroutine is
600** recovering from an error, 'ud' points to the error status, which must
601** be passed to the first continuation function (otherwise the default
602** status is LUA_YIELD).
603*/
604static void unroll (lua_State *L, void *ud) {
605 CallInfo *ci;
606 if (ud != NULL) /* error status? */
607 finishCcall(L, *(int *)ud); /* finish 'lua_pcallk' callee */
608 while ((ci = L->ci) != &L->base_ci) { /* something in the stack */
609 if (!isLua(ci)) /* C function? */
610 finishCcall(L, LUA_YIELD); /* complete its execution */
611 else { /* Lua function */
612 luaV_finishOp(L); /* finish interrupted instruction */
613 luaV_execute(L, ci); /* execute down to higher C 'boundary' */
614 }
615 }
616}
617
618
619/*
620** Try to find a suspended protected call (a "recover point") for the
621** given thread.
622*/
623static CallInfo *findpcall (lua_State *L) {
624 CallInfo *ci;
625 for (ci = L->ci; ci != NULL; ci = ci->previous) { /* search for a pcall */
626 if (ci->callstatus & CIST_YPCALL)
627 return ci;
628 }
629 return NULL; /* no pending pcall */
630}
631
632
633/*
634** Recovers from an error in a coroutine. Finds a recover point (if
635** there is one) and completes the execution of the interrupted
636** 'luaD_pcall'. If there is no recover point, returns zero.
637*/
638static int recover (lua_State *L, int status) {
639 StkId oldtop;
640 CallInfo *ci = findpcall(L);
641 if (ci == NULL) return 0; /* no recovery point */
642 /* "finish" luaD_pcall */
643 oldtop = restorestack(L, ci->u2.funcidx);
644 L->ci = ci;
645 L->allowhook = getoah(ci->callstatus); /* restore original 'allowhook' */
646 status = luaF_close(L, oldtop, status); /* may change the stack */
647 oldtop = restorestack(L, ci->u2.funcidx);
648 luaD_seterrorobj(L, status, oldtop);
649 luaD_shrinkstack(L); /* restore stack size in case of overflow */
650 L->errfunc = ci->u.c.old_errfunc;
651 return 1; /* continue running the coroutine */
652}
653
654
655/*
656** Signal an error in the call to 'lua_resume', not in the execution
657** of the coroutine itself. (Such errors should not be handled by any
658** coroutine error handler and should not kill the coroutine.)
659*/
660static int resume_error (lua_State *L, const char *msg, int narg) {
661 L->top -= narg; /* remove args from the stack */
662 setsvalue2s(L, L->top, luaS_new(L, msg)); /* push error message */
663 api_incr_top(L);
664 lua_unlock(L);
665 return LUA_ERRRUN;
666}
667
668
669/*
670** Do the work for 'lua_resume' in protected mode. Most of the work
671** depends on the status of the coroutine: initial state, suspended
672** inside a hook, or regularly suspended (optionally with a continuation
673** function), plus erroneous cases: non-suspended coroutine or dead
674** coroutine.
675*/
676static void resume (lua_State *L, void *ud) {
677 int n = *(cast(int*, ud)); /* number of arguments */
678 StkId firstArg = L->top - n; /* first argument */
679 CallInfo *ci = L->ci;
680 if (L->status == LUA_OK) /* starting a coroutine? */
681 docall(L, firstArg - 1, LUA_MULTRET, 1); /* just call its body */
682 else { /* resuming from previous yield */
683 lua_assert(L->status == LUA_YIELD);
684 L->status = LUA_OK; /* mark that it is running (again) */
685 luaE_incCstack(L); /* control the C stack */
686 if (isLua(ci)) /* yielded inside a hook? */
687 luaV_execute(L, ci); /* just continue running Lua code */
688 else { /* 'common' yield */
689 if (ci->u.c.k != NULL) { /* does it have a continuation function? */
690 lua_unlock(L);
691 n = (*ci->u.c.k)(L, LUA_YIELD, ci->u.c.ctx); /* call continuation */
692 lua_lock(L);
693 api_checknelems(L, n);
694 }
695 luaD_poscall(L, ci, n); /* finish 'luaD_call' */
696 }
697 unroll(L, NULL); /* run continuation */
698 }
699}
700
701LUA_API int lua_resume (lua_State *L, lua_State *from, int nargs,
702 int *nresults) {
703 int status;
704 lua_lock(L);
705 if (L->status == LUA_OK) { /* may be starting a coroutine */
706 if (L->ci != &L->base_ci) /* not in base level? */
707 return resume_error(L, "cannot resume non-suspended coroutine", nargs);
708 else if (L->top - (L->ci->func + 1) == nargs) /* no function? */
709 return resume_error(L, "cannot resume dead coroutine", nargs);
710 }
711 else if (L->status != LUA_YIELD) /* ended with errors? */
712 return resume_error(L, "cannot resume dead coroutine", nargs);
713 L->nCcalls = (from) ? getCcalls(from) : 0;
714 luai_userstateresume(L, nargs);
715 api_checknelems(L, (L->status == LUA_OK) ? nargs + 1 : nargs);
716 status = luaD_rawrunprotected(L, resume, &nargs);
717 /* continue running after recoverable errors */
718 while (errorstatus(status) && recover(L, status)) {
719 /* unroll continuation */
720 status = luaD_rawrunprotected(L, unroll, &status);
721 }
722 if (likely(!errorstatus(status)))
723 lua_assert(status == L->status); /* normal end or yield */
724 else { /* unrecoverable error */
725 L->status = cast_byte(status); /* mark thread as 'dead' */
726 luaD_seterrorobj(L, status, L->top); /* push error message */
727 L->ci->top = L->top;
728 }
729 *nresults = (status == LUA_YIELD) ? L->ci->u2.nyield
730 : cast_int(L->top - (L->ci->func + 1));
731 lua_unlock(L);
732 return status;
733}
734
735
736LUA_API int lua_isyieldable (lua_State *L) {
737 return yieldable(L);
738}
739
740
741LUA_API int lua_yieldk (lua_State *L, int nresults, lua_KContext ctx,
742 lua_KFunction k) {
743 CallInfo *ci;
744 luai_userstateyield(L, nresults);
745 lua_lock(L);
746 ci = L->ci;
747 api_checknelems(L, nresults);
748 if (unlikely(!yieldable(L))) {
749 if (L != G(L)->mainthread)
750 luaG_runerror(L, "attempt to yield across a C-call boundary");
751 else
752 luaG_runerror(L, "attempt to yield from outside a coroutine");
753 }
754 L->status = LUA_YIELD;
755 if (isLua(ci)) { /* inside a hook? */
756 lua_assert(!isLuacode(ci));
757 api_check(L, k == NULL, "hooks cannot continue after yielding");
758 ci->u2.nyield = 0; /* no results */
759 }
760 else {
761 if ((ci->u.c.k = k) != NULL) /* is there a continuation? */
762 ci->u.c.ctx = ctx; /* save context */
763 ci->u2.nyield = nresults; /* save number of results */
764 luaD_throw(L, LUA_YIELD);
765 }
766 lua_assert(ci->callstatus & CIST_HOOKED); /* must be inside a hook */
767 lua_unlock(L);
768 return 0; /* return to 'luaD_hook' */
769}
770
771
772/*
773** Call the C function 'func' in protected mode, restoring basic
774** thread information ('allowhook', etc.) and in particular
775** its stack level in case of errors.
776*/
777int luaD_pcall (lua_State *L, Pfunc func, void *u,
778 ptrdiff_t old_top, ptrdiff_t ef) {
779 int status;
780 CallInfo *old_ci = L->ci;
781 lu_byte old_allowhooks = L->allowhook;
782 ptrdiff_t old_errfunc = L->errfunc;
783 L->errfunc = ef;
784 status = luaD_rawrunprotected(L, func, u);
785 if (unlikely(status != LUA_OK)) { /* an error occurred? */
786 StkId oldtop = restorestack(L, old_top);
787 L->ci = old_ci;
788 L->allowhook = old_allowhooks;
789 status = luaF_close(L, oldtop, status);
790 oldtop = restorestack(L, old_top); /* previous call may change stack */
791 luaD_seterrorobj(L, status, oldtop);
792 luaD_shrinkstack(L); /* restore stack size in case of overflow */
793 }
794 L->errfunc = old_errfunc;
795 return status;
796}
797
798
799
800/*
801** Execute a protected parser.
802*/
803struct SParser { /* data to 'f_parser' */
804 ZIO *z;
805 Mbuffer buff; /* dynamic structure used by the scanner */
806 Dyndata dyd; /* dynamic structures used by the parser */
807 const char *mode;
808 const char *name;
809};
810
811
812static void checkmode (lua_State *L, const char *mode, const char *x) {
813 if (mode && strchr(mode, x[0]) == NULL) {
814 luaO_pushfstring(L,
815 "attempt to load a %s chunk (mode is '%s')", x, mode);
816 luaD_throw(L, LUA_ERRSYNTAX);
817 }
818}
819
820
821static void f_parser (lua_State *L, void *ud) {
822 LClosure *cl;
823 struct SParser *p = cast(struct SParser *, ud);
824 int c = zgetc(p->z); /* read first character */
825 if (c == LUA_SIGNATURE[0]) {
826 checkmode(L, p->mode, "binary");
827 cl = luaU_undump(L, p->z, p->name);
828 }
829 else {
830 checkmode(L, p->mode, "text");
831 cl = luaY_parser(L, p->z, &p->buff, &p->dyd, p->name, c);
832 }
833 lua_assert(cl->nupvalues == cl->p->sizeupvalues);
834 luaF_initupvals(L, cl);
835}
836
837
838int luaD_protectedparser (lua_State *L, ZIO *z, const char *name,
839 const char *mode) {
840 struct SParser p;
841 int status;
842 incnny(L); /* cannot yield during parsing */
843 p.z = z; p.name = name; p.mode = mode;
844 p.dyd.actvar.arr = NULL; p.dyd.actvar.size = 0;
845 p.dyd.gt.arr = NULL; p.dyd.gt.size = 0;
846 p.dyd.label.arr = NULL; p.dyd.label.size = 0;
847 luaZ_initbuffer(L, &p.buff);
848 status = luaD_pcall(L, f_parser, &p, savestack(L, L->top), L->errfunc);
849 luaZ_freebuffer(L, &p.buff);
850 luaM_freearray(L, p.dyd.actvar.arr, p.dyd.actvar.size);
851 luaM_freearray(L, p.dyd.gt.arr, p.dyd.gt.size);
852 luaM_freearray(L, p.dyd.label.arr, p.dyd.label.size);
853 decnny(L);
854 return status;
855}
856
857
858