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_OK: { /* special case only for closing upvalues */
98 setnilvalue(s2v(oldtop)); /* no error message */
99 break;
100 }
101 default: {
102 lua_assert(errorstatus(errcode)); /* real error */
103 setobjs2s(L, oldtop, L->top.p - 1); /* error message on current top */
104 break;
105 }
106 }
107 L->top.p = oldtop + 1;
108}
109
110
111l_noret luaD_throw (lua_State *L, int errcode) {
112 if (L->errorJmp) { /* thread has an error handler? */
113 L->errorJmp->status = errcode; /* set status */
114 LUAI_THROW(L, L->errorJmp); /* jump to it */
115 }
116 else { /* thread has no error handler */
117 global_State *g = G(L);
118 errcode = luaE_resetthread(L, errcode); /* close all upvalues */
119 L->status = errcode;
120 if (g->mainthread->errorJmp) { /* main thread has a handler? */
121 setobjs2s(L, g->mainthread->top.p++, L->top.p - 1); /* copy error obj. */
122 luaD_throw(g->mainthread, errcode); /* re-throw in main thread */
123 }
124 else { /* no handler at all; abort */
125 if (g->panic) { /* panic function? */
126 lua_unlock(L);
127 g->panic(L); /* call panic function (last chance to jump out) */
128 }
129 abort();
130 }
131 }
132}
133
134
135int luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud) {
136 l_uint32 oldnCcalls = L->nCcalls;
137 struct lua_longjmp lj;
138 lj.status = LUA_OK;
139 lj.previous = L->errorJmp; /* chain new error handler */
140 L->errorJmp = &lj;
141 LUAI_TRY(L, &lj,
142 (*f)(L, ud);
143 );
144 L->errorJmp = lj.previous; /* restore old error handler */
145 L->nCcalls = oldnCcalls;
146 return lj.status;
147}
148
149/* }====================================================== */
150
151
152/*
153** {==================================================================
154** Stack reallocation
155** ===================================================================
156*/
157
158
159/*
160** Change all pointers to the stack into offsets.
161*/
162static void relstack (lua_State *L) {
163 CallInfo *ci;
164 UpVal *up;
165 L->top.offset = savestack(L, L->top.p);
166 L->tbclist.offset = savestack(L, L->tbclist.p);
167 for (up = L->openupval; up != NULL; up = up->u.open.next)
168 up->v.offset = savestack(L, uplevel(up));
169 for (ci = L->ci; ci != NULL; ci = ci->previous) {
170 ci->top.offset = savestack(L, ci->top.p);
171 ci->func.offset = savestack(L, ci->func.p);
172 }
173}
174
175
176/*
177** Change back all offsets into pointers.
178*/
179static void correctstack (lua_State *L) {
180 CallInfo *ci;
181 UpVal *up;
182 L->top.p = restorestack(L, L->top.offset);
183 L->tbclist.p = restorestack(L, L->tbclist.offset);
184 for (up = L->openupval; up != NULL; up = up->u.open.next)
185 up->v.p = s2v(restorestack(L, up->v.offset));
186 for (ci = L->ci; ci != NULL; ci = ci->previous) {
187 ci->top.p = restorestack(L, ci->top.offset);
188 ci->func.p = restorestack(L, ci->func.offset);
189 if (isLua(ci))
190 ci->u.l.trap = 1; /* signal to update 'trap' in 'luaV_execute' */
191 }
192}
193
194
195/* some space for error handling */
196#define ERRORSTACKSIZE (LUAI_MAXSTACK + 200)
197
198
199/* raise an error while running the message handler */
200l_noret luaD_errerr (lua_State *L) {
201 TString *msg = luaS_newliteral(L, "error in error handling");
202 setsvalue2s(L, L->top.p, msg);
203 L->top.p++; /* assume EXTRA_STACK */
204 luaD_throw(L, LUA_ERRERR);
205}
206
207
208/*
209** Reallocate the stack to a new size, correcting all pointers into it.
210** In ISO C, any pointer use after the pointer has been deallocated is
211** undefined behavior. So, before the reallocation, all pointers are
212** changed to offsets, and after the reallocation they are changed back
213** to pointers. As during the reallocation the pointers are invalid, the
214** reallocation cannot run emergency collections.
215**
216** In case of allocation error, raise an error or return false according
217** to 'raiseerror'.
218*/
219int luaD_reallocstack (lua_State *L, int newsize, int raiseerror) {
220 int oldsize = stacksize(L);
221 int i;
222 StkId newstack;
223 int oldgcstop = G(L)->gcstopem;
224 lua_assert(newsize <= LUAI_MAXSTACK || newsize == ERRORSTACKSIZE);
225 relstack(L); /* change pointers to offsets */
226 G(L)->gcstopem = 1; /* stop emergency collection */
227 newstack = luaM_reallocvector(L, L->stack.p, oldsize + EXTRA_STACK,
228 newsize + EXTRA_STACK, StackValue);
229 G(L)->gcstopem = oldgcstop; /* restore emergency collection */
230 if (l_unlikely(newstack == NULL)) { /* reallocation failed? */
231 correctstack(L); /* change offsets back to pointers */
232 if (raiseerror)
233 luaM_error(L);
234 else return 0; /* do not raise an error */
235 }
236 L->stack.p = newstack;
237 correctstack(L); /* change offsets back to pointers */
238 L->stack_last.p = L->stack.p + newsize;
239 for (i = oldsize + EXTRA_STACK; i < newsize + EXTRA_STACK; i++)
240 setnilvalue(s2v(newstack + i)); /* erase new segment */
241 return 1;
242}
243
244
245/*
246** Try to grow the stack by at least 'n' elements. When 'raiseerror'
247** is true, raises any error; otherwise, return 0 in case of errors.
248*/
249int luaD_growstack (lua_State *L, int n, int raiseerror) {
250 int size = stacksize(L);
251 if (l_unlikely(size > LUAI_MAXSTACK)) {
252 /* if stack is larger than maximum, thread is already using the
253 extra space reserved for errors, that is, thread is handling
254 a stack error; cannot grow further than that. */
255 lua_assert(stacksize(L) == ERRORSTACKSIZE);
256 if (raiseerror)
257 luaD_errerr(L); /* error inside message handler */
258 return 0; /* if not 'raiseerror', just signal it */
259 }
260 else if (n < LUAI_MAXSTACK) { /* avoids arithmetic overflows */
261 int newsize = 2 * size; /* tentative new size */
262 int needed = cast_int(L->top.p - L->stack.p) + n;
263 if (newsize > LUAI_MAXSTACK) /* cannot cross the limit */
264 newsize = LUAI_MAXSTACK;
265 if (newsize < needed) /* but must respect what was asked for */
266 newsize = needed;
267 if (l_likely(newsize <= LUAI_MAXSTACK))
268 return luaD_reallocstack(L, newsize, raiseerror);
269 }
270 /* else stack overflow */
271 /* add extra size to be able to handle the error message */
272 luaD_reallocstack(L, ERRORSTACKSIZE, raiseerror);
273 if (raiseerror)
274 luaG_runerror(L, "stack overflow");
275 return 0;
276}
277
278
279/*
280** Compute how much of the stack is being used, by computing the
281** maximum top of all call frames in the stack and the current top.
282*/
283static int stackinuse (lua_State *L) {
284 CallInfo *ci;
285 int res;
286 StkId lim = L->top.p;
287 for (ci = L->ci; ci != NULL; ci = ci->previous) {
288 if (lim < ci->top.p) lim = ci->top.p;
289 }
290 lua_assert(lim <= L->stack_last.p + EXTRA_STACK);
291 res = cast_int(lim - L->stack.p) + 1; /* part of stack in use */
292 if (res < LUA_MINSTACK)
293 res = LUA_MINSTACK; /* ensure a minimum size */
294 return res;
295}
296
297
298/*
299** If stack size is more than 3 times the current use, reduce that size
300** to twice the current use. (So, the final stack size is at most 2/3 the
301** previous size, and half of its entries are empty.)
302** As a particular case, if stack was handling a stack overflow and now
303** it is not, 'max' (limited by LUAI_MAXSTACK) will be smaller than
304** stacksize (equal to ERRORSTACKSIZE in this case), and so the stack
305** will be reduced to a "regular" size.
306*/
307void luaD_shrinkstack (lua_State *L) {
308 int inuse = stackinuse(L);
309 int max = (inuse > LUAI_MAXSTACK / 3) ? LUAI_MAXSTACK : inuse * 3;
310 /* if thread is currently not handling a stack overflow and its
311 size is larger than maximum "reasonable" size, shrink it */
312 if (inuse <= LUAI_MAXSTACK && stacksize(L) > max) {
313 int nsize = (inuse > LUAI_MAXSTACK / 2) ? LUAI_MAXSTACK : inuse * 2;
314 luaD_reallocstack(L, nsize, 0); /* ok if that fails */
315 }
316 else /* don't change stack */
317 condmovestack(L,{},{}); /* (change only for debugging) */
318 luaE_shrinkCI(L); /* shrink CI list */
319}
320
321
322void luaD_inctop (lua_State *L) {
323 luaD_checkstack(L, 1);
324 L->top.p++;
325}
326
327/* }================================================================== */
328
329
330/*
331** Call a hook for the given event. Make sure there is a hook to be
332** called. (Both 'L->hook' and 'L->hookmask', which trigger this
333** function, can be changed asynchronously by signals.)
334*/
335void luaD_hook (lua_State *L, int event, int line,
336 int ftransfer, int ntransfer) {
337 lua_Hook hook = L->hook;
338 if (hook && L->allowhook) { /* make sure there is a hook */
339 int mask = CIST_HOOKED;
340 CallInfo *ci = L->ci;
341 ptrdiff_t top = savestack(L, L->top.p); /* preserve original 'top' */
342 ptrdiff_t ci_top = savestack(L, ci->top.p); /* idem for 'ci->top' */
343 lua_Debug ar;
344 ar.event = event;
345 ar.currentline = line;
346 ar.i_ci = ci;
347 if (ntransfer != 0) {
348 mask |= CIST_TRAN; /* 'ci' has transfer information */
349 ci->u2.transferinfo.ftransfer = ftransfer;
350 ci->u2.transferinfo.ntransfer = ntransfer;
351 }
352 if (isLua(ci) && L->top.p < ci->top.p)
353 L->top.p = ci->top.p; /* protect entire activation register */
354 luaD_checkstack(L, LUA_MINSTACK); /* ensure minimum stack size */
355 if (ci->top.p < L->top.p + LUA_MINSTACK)
356 ci->top.p = L->top.p + LUA_MINSTACK;
357 L->allowhook = 0; /* cannot call hooks inside a hook */
358 ci->callstatus |= mask;
359 lua_unlock(L);
360 (*hook)(L, &ar);
361 lua_lock(L);
362 lua_assert(!L->allowhook);
363 L->allowhook = 1;
364 ci->top.p = restorestack(L, ci_top);
365 L->top.p = restorestack(L, top);
366 ci->callstatus &= ~mask;
367 }
368}
369
370
371/*
372** Executes a call hook for Lua functions. This function is called
373** whenever 'hookmask' is not zero, so it checks whether call hooks are
374** active.
375*/
376void luaD_hookcall (lua_State *L, CallInfo *ci) {
377 L->oldpc = 0; /* set 'oldpc' for new function */
378 if (L->hookmask & LUA_MASKCALL) { /* is call hook on? */
379 int event = (ci->callstatus & CIST_TAIL) ? LUA_HOOKTAILCALL
380 : LUA_HOOKCALL;
381 Proto *p = ci_func(ci)->p;
382 ci->u.l.savedpc++; /* hooks assume 'pc' is already incremented */
383 luaD_hook(L, event, -1, 1, p->numparams);
384 ci->u.l.savedpc--; /* correct 'pc' */
385 }
386}
387
388
389/*
390** Executes a return hook for Lua and C functions and sets/corrects
391** 'oldpc'. (Note that this correction is needed by the line hook, so it
392** is done even when return hooks are off.)
393*/
394static void rethook (lua_State *L, CallInfo *ci, int nres) {
395 if (L->hookmask & LUA_MASKRET) { /* is return hook on? */
396 StkId firstres = L->top.p - nres; /* index of first result */
397 int delta = 0; /* correction for vararg functions */
398 int ftransfer;
399 if (isLua(ci)) {
400 Proto *p = ci_func(ci)->p;
401 if (p->is_vararg)
402 delta = ci->u.l.nextraargs + p->numparams + 1;
403 }
404 ci->func.p += delta; /* if vararg, back to virtual 'func' */
405 ftransfer = cast(unsigned short, firstres - ci->func.p);
406 luaD_hook(L, LUA_HOOKRET, -1, ftransfer, nres); /* call it */
407 ci->func.p -= delta;
408 }
409 if (isLua(ci = ci->previous))
410 L->oldpc = pcRel(ci->u.l.savedpc, ci_func(ci)->p); /* set 'oldpc' */
411}
412
413
414/*
415** Check whether 'func' has a '__call' metafield. If so, put it in the
416** stack, below original 'func', so that 'luaD_precall' can call it. Raise
417** an error if there is no '__call' metafield.
418*/
419static StkId tryfuncTM (lua_State *L, StkId func) {
420 const TValue *tm;
421 StkId p;
422 checkstackGCp(L, 1, func); /* space for metamethod */
423 tm = luaT_gettmbyobj(L, s2v(func), TM_CALL); /* (after previous GC) */
424 if (l_unlikely(ttisnil(tm)))
425 luaG_callerror(L, s2v(func)); /* nothing to call */
426 for (p = L->top.p; p > func; p--) /* open space for metamethod */
427 setobjs2s(L, p, p-1);
428 L->top.p++; /* stack space pre-allocated by the caller */
429 setobj2s(L, func, tm); /* metamethod is the new function to be called */
430 return func;
431}
432
433
434/*
435** Given 'nres' results at 'firstResult', move 'wanted' of them to 'res'.
436** Handle most typical cases (zero results for commands, one result for
437** expressions, multiple results for tail calls/single parameters)
438** separated.
439*/
440l_sinline void moveresults (lua_State *L, StkId res, int nres, int wanted) {
441 StkId firstresult;
442 int i;
443 switch (wanted) { /* handle typical cases separately */
444 case 0: /* no values needed */
445 L->top.p = res;
446 return;
447 case 1: /* one value needed */
448 if (nres == 0) /* no results? */
449 setnilvalue(s2v(res)); /* adjust with nil */
450 else /* at least one result */
451 setobjs2s(L, res, L->top.p - nres); /* move it to proper place */
452 L->top.p = res + 1;
453 return;
454 case LUA_MULTRET:
455 wanted = nres; /* we want all results */
456 break;
457 default: /* two/more results and/or to-be-closed variables */
458 if (hastocloseCfunc(wanted)) { /* to-be-closed variables? */
459 L->ci->callstatus |= CIST_CLSRET; /* in case of yields */
460 L->ci->u2.nres = nres;
461 res = luaF_close(L, res, CLOSEKTOP, 1);
462 L->ci->callstatus &= ~CIST_CLSRET;
463 if (L->hookmask) { /* if needed, call hook after '__close's */
464 ptrdiff_t savedres = savestack(L, res);
465 rethook(L, L->ci, nres);
466 res = restorestack(L, savedres); /* hook can move stack */
467 }
468 wanted = decodeNresults(wanted);
469 if (wanted == LUA_MULTRET)
470 wanted = nres; /* we want all results */
471 }
472 break;
473 }
474 /* generic case */
475 firstresult = L->top.p - nres; /* index of first result */
476 if (nres > wanted) /* extra results? */
477 nres = wanted; /* don't need them */
478 for (i = 0; i < nres; i++) /* move all results to correct place */
479 setobjs2s(L, res + i, firstresult + i);
480 for (; i < wanted; i++) /* complete wanted number of results */
481 setnilvalue(s2v(res + i));
482 L->top.p = res + wanted; /* top points after the last result */
483}
484
485
486/*
487** Finishes a function call: calls hook if necessary, moves current
488** number of results to proper place, and returns to previous call
489** info. If function has to close variables, hook must be called after
490** that.
491*/
492void luaD_poscall (lua_State *L, CallInfo *ci, int nres) {
493 int wanted = ci->nresults;
494 if (l_unlikely(L->hookmask && !hastocloseCfunc(wanted)))
495 rethook(L, ci, nres);
496 /* move results to proper place */
497 moveresults(L, ci->func.p, nres, wanted);
498 /* function cannot be in any of these cases when returning */
499 lua_assert(!(ci->callstatus &
500 (CIST_HOOKED | CIST_YPCALL | CIST_FIN | CIST_TRAN | CIST_CLSRET)));
501 L->ci = ci->previous; /* back to caller (after closing variables) */
502}
503
504
505
506#define next_ci(L) (L->ci->next ? L->ci->next : luaE_extendCI(L))
507
508
509l_sinline CallInfo *prepCallInfo (lua_State *L, StkId func, int nret,
510 int mask, StkId top) {
511 CallInfo *ci = L->ci = next_ci(L); /* new frame */
512 ci->func.p = func;
513 ci->nresults = nret;
514 ci->callstatus = mask;
515 ci->top.p = top;
516 return ci;
517}
518
519
520/*
521** precall for C functions
522*/
523l_sinline int precallC (lua_State *L, StkId func, int nresults,
524 lua_CFunction f) {
525 int n; /* number of returns */
526 CallInfo *ci;
527 checkstackGCp(L, LUA_MINSTACK, func); /* ensure minimum stack size */
528 L->ci = ci = prepCallInfo(L, func, nresults, CIST_C,
529 L->top.p + LUA_MINSTACK);
530 lua_assert(ci->top.p <= L->stack_last.p);
531 if (l_unlikely(L->hookmask & LUA_MASKCALL)) {
532 int narg = cast_int(L->top.p - func) - 1;
533 luaD_hook(L, LUA_HOOKCALL, -1, 1, narg);
534 }
535 lua_unlock(L);
536 n = (*f)(L); /* do the actual call */
537 lua_lock(L);
538 api_checknelems(L, n);
539 luaD_poscall(L, ci, n);
540 return n;
541}
542
543
544/*
545** Prepare a function for a tail call, building its call info on top
546** of the current call info. 'narg1' is the number of arguments plus 1
547** (so that it includes the function itself). Return the number of
548** results, if it was a C function, or -1 for a Lua function.
549*/
550int luaD_pretailcall (lua_State *L, CallInfo *ci, StkId func,
551 int narg1, int delta) {
552 retry:
553 switch (ttypetag(s2v(func))) {
554 case LUA_VCCL: /* C closure */
555 return precallC(L, func, LUA_MULTRET, clCvalue(s2v(func))->f);
556 case LUA_VLCF: /* light C function */
557 return precallC(L, func, LUA_MULTRET, fvalue(s2v(func)));
558 case LUA_VLCL: { /* Lua function */
559 Proto *p = clLvalue(s2v(func))->p;
560 int fsize = p->maxstacksize; /* frame size */
561 int nfixparams = p->numparams;
562 int i;
563 checkstackGCp(L, fsize - delta, func);
564 ci->func.p -= delta; /* restore 'func' (if vararg) */
565 for (i = 0; i < narg1; i++) /* move down function and arguments */
566 setobjs2s(L, ci->func.p + i, func + i);
567 func = ci->func.p; /* moved-down function */
568 for (; narg1 <= nfixparams; narg1++)
569 setnilvalue(s2v(func + narg1)); /* complete missing arguments */
570 ci->top.p = func + 1 + fsize; /* top for new function */
571 lua_assert(ci->top.p <= L->stack_last.p);
572 ci->u.l.savedpc = p->code; /* starting point */
573 ci->callstatus |= CIST_TAIL;
574 L->top.p = func + narg1; /* set top */
575 return -1;
576 }
577 default: { /* not a function */
578 func = tryfuncTM(L, func); /* try to get '__call' metamethod */
579 /* return luaD_pretailcall(L, ci, func, narg1 + 1, delta); */
580 narg1++;
581 goto retry; /* try again */
582 }
583 }
584}
585
586
587/*
588** Prepares the call to a function (C or Lua). For C functions, also do
589** the call. The function to be called is at '*func'. The arguments
590** are on the stack, right after the function. Returns the CallInfo
591** to be executed, if it was a Lua function. Otherwise (a C function)
592** returns NULL, with all the results on the stack, starting at the
593** original function position.
594*/
595CallInfo *luaD_precall (lua_State *L, StkId func, int nresults) {
596 retry:
597 switch (ttypetag(s2v(func))) {
598 case LUA_VCCL: /* C closure */
599 precallC(L, func, nresults, clCvalue(s2v(func))->f);
600 return NULL;
601 case LUA_VLCF: /* light C function */
602 precallC(L, func, nresults, fvalue(s2v(func)));
603 return NULL;
604 case LUA_VLCL: { /* Lua function */
605 CallInfo *ci;
606 Proto *p = clLvalue(s2v(func))->p;
607 int narg = cast_int(L->top.p - func) - 1; /* number of real arguments */
608 int nfixparams = p->numparams;
609 int fsize = p->maxstacksize; /* frame size */
610 checkstackGCp(L, fsize, func);
611 L->ci = ci = prepCallInfo(L, func, nresults, 0, func + 1 + fsize);
612 ci->u.l.savedpc = p->code; /* starting point */
613 for (; narg < nfixparams; narg++)
614 setnilvalue(s2v(L->top.p++)); /* complete missing arguments */
615 lua_assert(ci->top.p <= L->stack_last.p);
616 return ci;
617 }
618 default: { /* not a function */
619 func = tryfuncTM(L, func); /* try to get '__call' metamethod */
620 /* return luaD_precall(L, func, nresults); */
621 goto retry; /* try again with metamethod */
622 }
623 }
624}
625
626
627/*
628** Call a function (C or Lua) through C. 'inc' can be 1 (increment
629** number of recursive invocations in the C stack) or nyci (the same
630** plus increment number of non-yieldable calls).
631** This function can be called with some use of EXTRA_STACK, so it should
632** check the stack before doing anything else. 'luaD_precall' already
633** does that.
634*/
635l_sinline void ccall (lua_State *L, StkId func, int nResults, l_uint32 inc) {
636 CallInfo *ci;
637 L->nCcalls += inc;
638 if (l_unlikely(getCcalls(L) >= LUAI_MAXCCALLS)) {
639 checkstackp(L, 0, func); /* free any use of EXTRA_STACK */
640 luaE_checkcstack(L);
641 }
642 if ((ci = luaD_precall(L, func, nResults)) != NULL) { /* Lua function? */
643 ci->callstatus = CIST_FRESH; /* mark that it is a "fresh" execute */
644 luaV_execute(L, ci); /* call it */
645 }
646 L->nCcalls -= inc;
647}
648
649
650/*
651** External interface for 'ccall'
652*/
653void luaD_call (lua_State *L, StkId func, int nResults) {
654 ccall(L, func, nResults, 1);
655}
656
657
658/*
659** Similar to 'luaD_call', but does not allow yields during the call.
660*/
661void luaD_callnoyield (lua_State *L, StkId func, int nResults) {
662 ccall(L, func, nResults, nyci);
663}
664
665
666/*
667** Finish the job of 'lua_pcallk' after it was interrupted by an yield.
668** (The caller, 'finishCcall', does the final call to 'adjustresults'.)
669** The main job is to complete the 'luaD_pcall' called by 'lua_pcallk'.
670** If a '__close' method yields here, eventually control will be back
671** to 'finishCcall' (when that '__close' method finally returns) and
672** 'finishpcallk' will run again and close any still pending '__close'
673** methods. Similarly, if a '__close' method errs, 'precover' calls
674** 'unroll' which calls ''finishCcall' and we are back here again, to
675** close any pending '__close' methods.
676** Note that, up to the call to 'luaF_close', the corresponding
677** 'CallInfo' is not modified, so that this repeated run works like the
678** first one (except that it has at least one less '__close' to do). In
679** particular, field CIST_RECST preserves the error status across these
680** multiple runs, changing only if there is a new error.
681*/
682static int finishpcallk (lua_State *L, CallInfo *ci) {
683 int status = getcistrecst(ci); /* get original status */
684 if (l_likely(status == LUA_OK)) /* no error? */
685 status = LUA_YIELD; /* was interrupted by an yield */
686 else { /* error */
687 StkId func = restorestack(L, ci->u2.funcidx);
688 L->allowhook = getoah(ci->callstatus); /* restore 'allowhook' */
689 func = luaF_close(L, func, status, 1); /* can yield or raise an error */
690 luaD_seterrorobj(L, status, func);
691 luaD_shrinkstack(L); /* restore stack size in case of overflow */
692 setcistrecst(ci, LUA_OK); /* clear original status */
693 }
694 ci->callstatus &= ~CIST_YPCALL;
695 L->errfunc = ci->u.c.old_errfunc;
696 /* if it is here, there were errors or yields; unlike 'lua_pcallk',
697 do not change status */
698 return status;
699}
700
701
702/*
703** Completes the execution of a C function interrupted by an yield.
704** The interruption must have happened while the function was either
705** closing its tbc variables in 'moveresults' or executing
706** 'lua_callk'/'lua_pcallk'. In the first case, it just redoes
707** 'luaD_poscall'. In the second case, the call to 'finishpcallk'
708** finishes the interrupted execution of 'lua_pcallk'. After that, it
709** calls the continuation of the interrupted function and finally it
710** completes the job of the 'luaD_call' that called the function. In
711** the call to 'adjustresults', we do not know the number of results
712** of the function called by 'lua_callk'/'lua_pcallk', so we are
713** conservative and use LUA_MULTRET (always adjust).
714*/
715static void finishCcall (lua_State *L, CallInfo *ci) {
716 int n; /* actual number of results from C function */
717 if (ci->callstatus & CIST_CLSRET) { /* was returning? */
718 lua_assert(hastocloseCfunc(ci->nresults));
719 n = ci->u2.nres; /* just redo 'luaD_poscall' */
720 /* don't need to reset CIST_CLSRET, as it will be set again anyway */
721 }
722 else {
723 int status = LUA_YIELD; /* default if there were no errors */
724 /* must have a continuation and must be able to call it */
725 lua_assert(ci->u.c.k != NULL && yieldable(L));
726 if (ci->callstatus & CIST_YPCALL) /* was inside a 'lua_pcallk'? */
727 status = finishpcallk(L, ci); /* finish it */
728 adjustresults(L, LUA_MULTRET); /* finish 'lua_callk' */
729 lua_unlock(L);
730 n = (*ci->u.c.k)(L, status, ci->u.c.ctx); /* call continuation */
731 lua_lock(L);
732 api_checknelems(L, n);
733 }
734 luaD_poscall(L, ci, n); /* finish 'luaD_call' */
735}
736
737
738/*
739** Executes "full continuation" (everything in the stack) of a
740** previously interrupted coroutine until the stack is empty (or another
741** interruption long-jumps out of the loop).
742*/
743static void unroll (lua_State *L, void *ud) {
744 CallInfo *ci;
745 UNUSED(ud);
746 while ((ci = L->ci) != &L->base_ci) { /* something in the stack */
747 if (!isLua(ci)) /* C function? */
748 finishCcall(L, ci); /* complete its execution */
749 else { /* Lua function */
750 luaV_finishOp(L); /* finish interrupted instruction */
751 luaV_execute(L, ci); /* execute down to higher C 'boundary' */
752 }
753 }
754}
755
756
757/*
758** Try to find a suspended protected call (a "recover point") for the
759** given thread.
760*/
761static CallInfo *findpcall (lua_State *L) {
762 CallInfo *ci;
763 for (ci = L->ci; ci != NULL; ci = ci->previous) { /* search for a pcall */
764 if (ci->callstatus & CIST_YPCALL)
765 return ci;
766 }
767 return NULL; /* no pending pcall */
768}
769
770
771/*
772** Signal an error in the call to 'lua_resume', not in the execution
773** of the coroutine itself. (Such errors should not be handled by any
774** coroutine error handler and should not kill the coroutine.)
775*/
776static int resume_error (lua_State *L, const char *msg, int narg) {
777 L->top.p -= narg; /* remove args from the stack */
778 setsvalue2s(L, L->top.p, luaS_new(L, msg)); /* push error message */
779 api_incr_top(L);
780 lua_unlock(L);
781 return LUA_ERRRUN;
782}
783
784
785/*
786** Do the work for 'lua_resume' in protected mode. Most of the work
787** depends on the status of the coroutine: initial state, suspended
788** inside a hook, or regularly suspended (optionally with a continuation
789** function), plus erroneous cases: non-suspended coroutine or dead
790** coroutine.
791*/
792static void resume (lua_State *L, void *ud) {
793 int n = *(cast(int*, ud)); /* number of arguments */
794 StkId firstArg = L->top.p - n; /* first argument */
795 CallInfo *ci = L->ci;
796 if (L->status == LUA_OK) /* starting a coroutine? */
797 ccall(L, firstArg - 1, LUA_MULTRET, 0); /* just call its body */
798 else { /* resuming from previous yield */
799 lua_assert(L->status == LUA_YIELD);
800 L->status = LUA_OK; /* mark that it is running (again) */
801 if (isLua(ci)) { /* yielded inside a hook? */
802 /* undo increment made by 'luaG_traceexec': instruction was not
803 executed yet */
804 lua_assert(ci->callstatus & CIST_HOOKYIELD);
805 ci->u.l.savedpc--;
806 L->top.p = firstArg; /* discard arguments */
807 luaV_execute(L, ci); /* just continue running Lua code */
808 }
809 else { /* 'common' yield */
810 if (ci->u.c.k != NULL) { /* does it have a continuation function? */
811 lua_unlock(L);
812 n = (*ci->u.c.k)(L, LUA_YIELD, ci->u.c.ctx); /* call continuation */
813 lua_lock(L);
814 api_checknelems(L, n);
815 }
816 luaD_poscall(L, ci, n); /* finish 'luaD_call' */
817 }
818 unroll(L, NULL); /* run continuation */
819 }
820}
821
822
823/*
824** Unrolls a coroutine in protected mode while there are recoverable
825** errors, that is, errors inside a protected call. (Any error
826** interrupts 'unroll', and this loop protects it again so it can
827** continue.) Stops with a normal end (status == LUA_OK), an yield
828** (status == LUA_YIELD), or an unprotected error ('findpcall' doesn't
829** find a recover point).
830*/
831static int precover (lua_State *L, int status) {
832 CallInfo *ci;
833 while (errorstatus(status) && (ci = findpcall(L)) != NULL) {
834 L->ci = ci; /* go down to recovery functions */
835 setcistrecst(ci, status); /* status to finish 'pcall' */
836 status = luaD_rawrunprotected(L, unroll, NULL);
837 }
838 return status;
839}
840
841
842LUA_API int lua_resume (lua_State *L, lua_State *from, int nargs,
843 int *nresults) {
844 int status;
845 lua_lock(L);
846 if (L->status == LUA_OK) { /* may be starting a coroutine */
847 if (L->ci != &L->base_ci) /* not in base level? */
848 return resume_error(L, "cannot resume non-suspended coroutine", nargs);
849 else if (L->top.p - (L->ci->func.p + 1) == nargs) /* no function? */
850 return resume_error(L, "cannot resume dead coroutine", nargs);
851 }
852 else if (L->status != LUA_YIELD) /* ended with errors? */
853 return resume_error(L, "cannot resume dead coroutine", nargs);
854 L->nCcalls = (from) ? getCcalls(from) : 0;
855 if (getCcalls(L) >= LUAI_MAXCCALLS)
856 return resume_error(L, "C stack overflow", nargs);
857 L->nCcalls++;
858 luai_userstateresume(L, nargs);
859 api_checknelems(L, (L->status == LUA_OK) ? nargs + 1 : nargs);
860 status = luaD_rawrunprotected(L, resume, &nargs);
861 /* continue running after recoverable errors */
862 status = precover(L, status);
863 if (l_likely(!errorstatus(status)))
864 lua_assert(status == L->status); /* normal end or yield */
865 else { /* unrecoverable error */
866 L->status = cast_byte(status); /* mark thread as 'dead' */
867 luaD_seterrorobj(L, status, L->top.p); /* push error message */
868 L->ci->top.p = L->top.p;
869 }
870 *nresults = (status == LUA_YIELD) ? L->ci->u2.nyield
871 : cast_int(L->top.p - (L->ci->func.p + 1));
872 lua_unlock(L);
873 return status;
874}
875
876
877LUA_API int lua_isyieldable (lua_State *L) {
878 return yieldable(L);
879}
880
881
882LUA_API int lua_yieldk (lua_State *L, int nresults, lua_KContext ctx,
883 lua_KFunction k) {
884 CallInfo *ci;
885 luai_userstateyield(L, nresults);
886 lua_lock(L);
887 ci = L->ci;
888 api_checknelems(L, nresults);
889 if (l_unlikely(!yieldable(L))) {
890 if (L != G(L)->mainthread)
891 luaG_runerror(L, "attempt to yield across a C-call boundary");
892 else
893 luaG_runerror(L, "attempt to yield from outside a coroutine");
894 }
895 L->status = LUA_YIELD;
896 ci->u2.nyield = nresults; /* save number of results */
897 if (isLua(ci)) { /* inside a hook? */
898 lua_assert(!isLuacode(ci));
899 api_check(L, nresults == 0, "hooks cannot yield values");
900 api_check(L, k == NULL, "hooks cannot continue after yielding");
901 }
902 else {
903 if ((ci->u.c.k = k) != NULL) /* is there a continuation? */
904 ci->u.c.ctx = ctx; /* save context */
905 luaD_throw(L, LUA_YIELD);
906 }
907 lua_assert(ci->callstatus & CIST_HOOKED); /* must be inside a hook */
908 lua_unlock(L);
909 return 0; /* return to 'luaD_hook' */
910}
911
912
913/*
914** Auxiliary structure to call 'luaF_close' in protected mode.
915*/
916struct CloseP {
917 StkId level;
918 int status;
919};
920
921
922/*
923** Auxiliary function to call 'luaF_close' in protected mode.
924*/
925static void closepaux (lua_State *L, void *ud) {
926 struct CloseP *pcl = cast(struct CloseP *, ud);
927 luaF_close(L, pcl->level, pcl->status, 0);
928}
929
930
931/*
932** Calls 'luaF_close' in protected mode. Return the original status
933** or, in case of errors, the new status.
934*/
935int luaD_closeprotected (lua_State *L, ptrdiff_t level, int status) {
936 CallInfo *old_ci = L->ci;
937 lu_byte old_allowhooks = L->allowhook;
938 for (;;) { /* keep closing upvalues until no more errors */
939 struct CloseP pcl;
940 pcl.level = restorestack(L, level); pcl.status = status;
941 status = luaD_rawrunprotected(L, &closepaux, &pcl);
942 if (l_likely(status == LUA_OK)) /* no more errors? */
943 return pcl.status;
944 else { /* an error occurred; restore saved state and repeat */
945 L->ci = old_ci;
946 L->allowhook = old_allowhooks;
947 }
948 }
949}
950
951
952/*
953** Call the C function 'func' in protected mode, restoring basic
954** thread information ('allowhook', etc.) and in particular
955** its stack level in case of errors.
956*/
957int luaD_pcall (lua_State *L, Pfunc func, void *u,
958 ptrdiff_t old_top, ptrdiff_t ef) {
959 int status;
960 CallInfo *old_ci = L->ci;
961 lu_byte old_allowhooks = L->allowhook;
962 ptrdiff_t old_errfunc = L->errfunc;
963 L->errfunc = ef;
964 status = luaD_rawrunprotected(L, func, u);
965 if (l_unlikely(status != LUA_OK)) { /* an error occurred? */
966 L->ci = old_ci;
967 L->allowhook = old_allowhooks;
968 status = luaD_closeprotected(L, old_top, status);
969 luaD_seterrorobj(L, status, restorestack(L, old_top));
970 luaD_shrinkstack(L); /* restore stack size in case of overflow */
971 }
972 L->errfunc = old_errfunc;
973 return status;
974}
975
976
977
978/*
979** Execute a protected parser.
980*/
981struct SParser { /* data to 'f_parser' */
982 ZIO *z;
983 Mbuffer buff; /* dynamic structure used by the scanner */
984 Dyndata dyd; /* dynamic structures used by the parser */
985 const char *mode;
986 const char *name;
987};
988
989
990static void checkmode (lua_State *L, const char *mode, const char *x) {
991 if (mode && strchr(mode, x[0]) == NULL) {
992 luaO_pushfstring(L,
993 "attempt to load a %s chunk (mode is '%s')", x, mode);
994 luaD_throw(L, LUA_ERRSYNTAX);
995 }
996}
997
998
999static void f_parser (lua_State *L, void *ud) {
1000 LClosure *cl;
1001 struct SParser *p = cast(struct SParser *, ud);
1002 int c = zgetc(p->z); /* read first character */
1003 if (c == LUA_SIGNATURE[0]) {
1004 checkmode(L, p->mode, "binary");
1005 cl = luaU_undump(L, p->z, p->name);
1006 }
1007 else {
1008 checkmode(L, p->mode, "text");
1009 cl = luaY_parser(L, p->z, &p->buff, &p->dyd, p->name, c);
1010 }
1011 lua_assert(cl->nupvalues == cl->p->sizeupvalues);
1012 luaF_initupvals(L, cl);
1013}
1014
1015
1016int luaD_protectedparser (lua_State *L, ZIO *z, const char *name,
1017 const char *mode) {
1018 struct SParser p;
1019 int status;
1020 incnny(L); /* cannot yield during parsing */
1021 p.z = z; p.name = name; p.mode = mode;
1022 p.dyd.actvar.arr = NULL; p.dyd.actvar.size = 0;
1023 p.dyd.gt.arr = NULL; p.dyd.gt.size = 0;
1024 p.dyd.label.arr = NULL; p.dyd.label.size = 0;
1025 luaZ_initbuffer(L, &p.buff);
1026 status = luaD_pcall(L, f_parser, &p, savestack(L, L->top.p), L->errfunc);
1027 luaZ_freebuffer(L, &p.buff);
1028 luaM_freearray(L, p.dyd.actvar.arr, p.dyd.actvar.size);
1029 luaM_freearray(L, p.dyd.gt.arr, p.dyd.gt.size);
1030 luaM_freearray(L, p.dyd.label.arr, p.dyd.label.size);
1031 decnny(L);
1032 return status;
1033}
1034
1035