2 ** $Id: ldo.c,v 2.108.1.3 2013/11/08 18:22:50 roberto Exp $
3 ** Stack and Call structure of Lua
4 ** See Copyright Notice in lua.h
38 ** {======================================================
39 ** Error-recovery functions
40 ** =======================================================
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.
49 #if !defined(LUAI_THROW)
51 #if defined(__cplusplus) && !defined(LUA_USE_LONGJMP)
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 */
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
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
76 /* chain list of long jump buffers */
78 struct lua_longjmp
*previous
;
80 volatile int status
; /* error code */
84 static void seterrorobj (lua_State
*L
, int errcode
, StkId oldtop
) {
86 case LUA_ERRMEM
: { /* memory error? */
87 setsvalue2s(L
, oldtop
, G(L
)->memerrmsg
); /* reuse preregistered msg. */
91 setsvalue2s(L
, oldtop
, luaS_newliteral(L
, "error in error handling"));
95 setobjs2s(L
, oldtop
, L
->top
- 1); /* error message on current top */
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 */
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 */
114 else { /* no handler at all; abort */
115 if (G(L
)->panic
) { /* panic function? */
117 G(L
)->panic(L
); /* call it (last chance to jump out) */
125 int luaD_rawrunprotected (lua_State
*L
, Pfunc f
, void *ud
) {
126 unsigned short oldnCcalls
= L
->nCcalls
;
127 struct lua_longjmp lj
;
129 lj
.previous
= L
->errorJmp
; /* chain new error handler */
134 L
->errorJmp
= lj
.previous
; /* restore old error handler */
135 L
->nCcalls
= oldnCcalls
;
139 /* }====================================================== */
142 static void correctstack (lua_State
*L
, TValue
*oldstack
) {
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
;
152 ci
->u
.l
.base
= (ci
->u
.l
.base
- oldstack
) + L
->stack
;
157 /* some space for error handling */
158 #define ERRORSTACKSIZE (LUAI_MAXSTACK + 200)
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
);
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
);
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");
189 luaD_reallocstack(L
, newsize
);
194 static int stackinuse (lua_State
*L
) {
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
;
201 return cast_int(lim
- L
->stack
) + 1; /* part of stack in use */
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) */
213 luaD_reallocstack(L
, goodsize
); /* shrink it */
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
);
225 ar
.currentline
= line
;
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
;
235 lua_assert(!L
->allowhook
);
237 ci
->top
= restorestack(L
, ci_top
);
238 L
->top
= restorestack(L
, top
);
239 ci
->callstatus
&= ~CIST_HOOKED
;
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
;
252 luaD_hook(L
, hook
, -1);
253 ci
->u
.l
.savedpc
--; /* correct 'pc' */
257 static StkId
adjust_varargs (lua_State
*L
, Proto
*p
, int actual
) {
259 int nfixargs
= p
->numparams
;
261 lua_assert(actual
>= nfixargs
);
262 /* move fixed parameters to final position */
263 luaD_checkstack(L
, p
->maxstacksize
); /* check again for new 'base' */
264 fixed
= L
->top
- actual
; /* first fixed argument */
265 base
= L
->top
; /* final position of first argument */
266 for (i
=0; i
<nfixargs
; i
++) {
267 setobjs2s(L
, L
->top
++, fixed
+ i
);
268 setnilvalue(fixed
+ i
);
274 static StkId
tryfuncTM (lua_State
*L
, StkId func
) {
275 const TValue
*tm
= luaT_gettmbyobj(L
, func
, TM_CALL
);
277 ptrdiff_t funcr
= savestack(L
, func
);
278 if (!ttisfunction(tm
))
279 luaG_typeerror(L
, func
, "call");
280 /* Open a hole inside the stack at `func' */
281 for (p
= L
->top
; p
> func
; p
--) setobjs2s(L
, p
, p
-1);
283 func
= restorestack(L
, funcr
); /* previous call may change stack */
284 setobj2s(L
, func
, tm
); /* tag method is the new function to be called */
290 #define next_ci(L) (L->ci = (L->ci->next ? L->ci->next : luaE_extendCI(L)))
294 ** returns true if function has been executed (C function)
296 int luaD_precall (lua_State
*L
, StkId func
, int nresults
) {
299 int n
; /* number of arguments (Lua) or returns (C) */
300 ptrdiff_t funcr
= savestack(L
, func
);
301 switch (ttype(func
)) {
302 case LUA_TLCF
: /* light C function */
305 case LUA_TCCL
: { /* C closure */
306 f
= clCvalue(func
)->f
;
308 luaD_checkstack(L
, LUA_MINSTACK
); /* ensure minimum stack size */
309 ci
= next_ci(L
); /* now 'enter' new function */
310 ci
->nresults
= nresults
;
311 ci
->func
= restorestack(L
, funcr
);
312 ci
->top
= L
->top
+ LUA_MINSTACK
;
313 lua_assert(ci
->top
<= L
->stack_last
);
315 luaC_checkGC(L
); /* stack grow uses memory */
316 if (L
->hookmask
& LUA_MASKCALL
)
317 luaD_hook(L
, LUA_HOOKCALL
, -1);
319 n
= (*f
)(L
); /* do the actual call */
321 api_checknelems(L
, n
);
322 luaD_poscall(L
, L
->top
- n
);
325 case LUA_TLCL
: { /* Lua function: prepare its call */
327 Proto
*p
= clLvalue(func
)->p
;
328 n
= cast_int(L
->top
- func
) - 1; /* number of real arguments */
329 luaD_checkstack(L
, p
->maxstacksize
);
330 for (; n
< p
->numparams
; n
++)
331 setnilvalue(L
->top
++); /* complete missing arguments */
333 func
= restorestack(L
, funcr
);
337 base
= adjust_varargs(L
, p
, n
);
338 func
= restorestack(L
, funcr
); /* previous call can change stack */
340 ci
= next_ci(L
); /* now 'enter' new function */
341 ci
->nresults
= nresults
;
344 ci
->top
= base
+ p
->maxstacksize
;
345 lua_assert(ci
->top
<= L
->stack_last
);
346 ci
->u
.l
.savedpc
= p
->code
; /* starting point */
347 ci
->callstatus
= CIST_LUA
;
349 luaC_checkGC(L
); /* stack grow uses memory */
350 if (L
->hookmask
& LUA_MASKCALL
)
354 default: { /* not a function */
355 func
= tryfuncTM(L
, func
); /* retry with 'function' tag method */
356 return luaD_precall(L
, func
, nresults
); /* now it must be a function */
362 int luaD_poscall (lua_State
*L
, StkId firstResult
) {
365 CallInfo
*ci
= L
->ci
;
366 if (L
->hookmask
& (LUA_MASKRET
| LUA_MASKLINE
)) {
367 if (L
->hookmask
& LUA_MASKRET
) {
368 ptrdiff_t fr
= savestack(L
, firstResult
); /* hook may change stack */
369 luaD_hook(L
, LUA_HOOKRET
, -1);
370 firstResult
= restorestack(L
, fr
);
372 L
->oldpc
= ci
->previous
->u
.l
.savedpc
; /* 'oldpc' for caller function */
374 res
= ci
->func
; /* res == final position of 1st result */
375 wanted
= ci
->nresults
;
376 L
->ci
= ci
= ci
->previous
; /* back to caller */
377 /* move results to correct place */
378 for (i
= wanted
; i
!= 0 && firstResult
< L
->top
; i
--)
379 setobjs2s(L
, res
++, firstResult
++);
383 return (wanted
- LUA_MULTRET
); /* 0 iff wanted == LUA_MULTRET */
388 ** Call a function (C or Lua). The function to be called is at *func.
389 ** The arguments are on the stack, right after the function.
390 ** When returns, all the results are on the stack, starting at the original
391 ** function position.
393 void luaD_call (lua_State
*L
, StkId func
, int nResults
, int allowyield
) {
394 if (++L
->nCcalls
>= LUAI_MAXCCALLS
) {
395 if (L
->nCcalls
== LUAI_MAXCCALLS
)
396 luaG_runerror(L
, "C stack overflow");
397 else if (L
->nCcalls
>= (LUAI_MAXCCALLS
+ (LUAI_MAXCCALLS
>>3)))
398 luaD_throw(L
, LUA_ERRERR
); /* error while handing stack error */
400 if (!allowyield
) L
->nny
++;
401 if (!luaD_precall(L
, func
, nResults
)) /* is a Lua function? */
402 luaV_execute(L
); /* call it */
403 if (!allowyield
) L
->nny
--;
408 static void finishCcall (lua_State
*L
) {
409 CallInfo
*ci
= L
->ci
;
411 lua_assert(ci
->u
.c
.k
!= NULL
); /* must have a continuation */
412 lua_assert(L
->nny
== 0);
413 if (ci
->callstatus
& CIST_YPCALL
) { /* was inside a pcall? */
414 ci
->callstatus
&= ~CIST_YPCALL
; /* finish 'lua_pcall' */
415 L
->errfunc
= ci
->u
.c
.old_errfunc
;
417 /* finish 'lua_callk'/'lua_pcall' */
418 adjustresults(L
, ci
->nresults
);
419 /* call continuation function */
420 if (!(ci
->callstatus
& CIST_STAT
)) /* no call status? */
421 ci
->u
.c
.status
= LUA_YIELD
; /* 'default' status */
422 lua_assert(ci
->u
.c
.status
!= LUA_OK
);
423 ci
->callstatus
= (ci
->callstatus
& ~(CIST_YPCALL
| CIST_STAT
)) | CIST_YIELDED
;
427 api_checknelems(L
, n
);
428 /* finish 'luaD_precall' */
429 luaD_poscall(L
, L
->top
- n
);
433 static void unroll (lua_State
*L
, void *ud
) {
436 if (L
->ci
== &L
->base_ci
) /* stack is empty? */
437 return; /* coroutine finished normally */
438 if (!isLua(L
->ci
)) /* C function? */
440 else { /* Lua function */
441 luaV_finishOp(L
); /* finish interrupted instruction */
442 luaV_execute(L
); /* execute down to higher C 'boundary' */
449 ** check whether thread has a suspended protected call
451 static CallInfo
*findpcall (lua_State
*L
) {
453 for (ci
= L
->ci
; ci
!= NULL
; ci
= ci
->previous
) { /* search for a pcall */
454 if (ci
->callstatus
& CIST_YPCALL
)
457 return NULL
; /* no pending pcall */
461 static int recover (lua_State
*L
, int status
) {
463 CallInfo
*ci
= findpcall(L
);
464 if (ci
== NULL
) return 0; /* no recovery point */
465 /* "finish" luaD_pcall */
466 oldtop
= restorestack(L
, ci
->extra
);
467 luaF_close(L
, oldtop
);
468 seterrorobj(L
, status
, oldtop
);
470 L
->allowhook
= ci
->u
.c
.old_allowhook
;
471 L
->nny
= 0; /* should be zero to be yieldable */
473 L
->errfunc
= ci
->u
.c
.old_errfunc
;
474 ci
->callstatus
|= CIST_STAT
; /* call has error status */
475 ci
->u
.c
.status
= status
; /* (here it is) */
476 return 1; /* continue running the coroutine */
481 ** signal an error in the call to 'resume', not in the execution of the
482 ** coroutine itself. (Such errors should not be handled by any coroutine
483 ** error handler and should not kill the coroutine.)
485 static l_noret
resume_error (lua_State
*L
, const char *msg
, StkId firstArg
) {
486 L
->top
= firstArg
; /* remove args from the stack */
487 setsvalue2s(L
, L
->top
, luaS_new(L
, msg
)); /* push error message */
489 luaD_throw(L
, -1); /* jump back to 'lua_resume' */
494 ** do the work for 'lua_resume' in protected mode
496 static void resume (lua_State
*L
, void *ud
) {
497 int nCcalls
= L
->nCcalls
;
498 StkId firstArg
= cast(StkId
, ud
);
499 CallInfo
*ci
= L
->ci
;
500 if (nCcalls
>= LUAI_MAXCCALLS
)
501 resume_error(L
, "C stack overflow", firstArg
);
502 if (L
->status
== LUA_OK
) { /* may be starting a coroutine */
503 if (ci
!= &L
->base_ci
) /* not in base level? */
504 resume_error(L
, "cannot resume non-suspended coroutine", firstArg
);
505 /* coroutine is in base level; start running it */
506 if (!luaD_precall(L
, firstArg
- 1, LUA_MULTRET
)) /* Lua function? */
507 luaV_execute(L
); /* call it */
509 else if (L
->status
!= LUA_YIELD
)
510 resume_error(L
, "cannot resume dead coroutine", firstArg
);
511 else { /* resuming from previous yield */
513 ci
->func
= restorestack(L
, ci
->extra
);
514 if (isLua(ci
)) /* yielded inside a hook? */
515 luaV_execute(L
); /* just continue running Lua code */
516 else { /* 'common' yield */
517 if (ci
->u
.c
.k
!= NULL
) { /* does it have a continuation? */
519 ci
->u
.c
.status
= LUA_YIELD
; /* 'default' status */
520 ci
->callstatus
|= CIST_YIELDED
;
522 n
= (*ci
->u
.c
.k
)(L
); /* call continuation */
524 api_checknelems(L
, n
);
525 firstArg
= L
->top
- n
; /* yield results come from continuation */
527 luaD_poscall(L
, firstArg
); /* finish 'luaD_precall' */
531 lua_assert(nCcalls
== L
->nCcalls
);
535 LUA_API
int lua_resume (lua_State
*L
, lua_State
*from
, int nargs
) {
537 int oldnny
= L
->nny
; /* save 'nny' */
539 luai_userstateresume(L
, nargs
);
540 L
->nCcalls
= (from
) ? from
->nCcalls
+ 1 : 1;
541 L
->nny
= 0; /* allow yields */
542 api_checknelems(L
, (L
->status
== LUA_OK
) ? nargs
+ 1 : nargs
);
543 status
= luaD_rawrunprotected(L
, resume
, L
->top
- nargs
);
544 if (status
== -1) /* error calling 'lua_resume'? */
546 else { /* yield or regular error */
547 while (status
!= LUA_OK
&& status
!= LUA_YIELD
) { /* error? */
548 if (recover(L
, status
)) /* recover point? */
549 status
= luaD_rawrunprotected(L
, unroll
, NULL
); /* run continuation */
550 else { /* unrecoverable error */
551 L
->status
= cast_byte(status
); /* mark thread as `dead' */
552 seterrorobj(L
, status
, L
->top
);
557 lua_assert(status
== L
->status
);
559 L
->nny
= oldnny
; /* restore 'nny' */
561 lua_assert(L
->nCcalls
== ((from
) ? from
->nCcalls
: 0));
567 LUA_API
int lua_yieldk (lua_State
*L
, int nresults
, int ctx
, lua_CFunction k
) {
568 CallInfo
*ci
= L
->ci
;
569 luai_userstateyield(L
, nresults
);
571 api_checknelems(L
, nresults
);
573 if (L
!= G(L
)->mainthread
)
574 luaG_runerror(L
, "attempt to yield across a C-call boundary");
576 luaG_runerror(L
, "attempt to yield from outside a coroutine");
578 L
->status
= LUA_YIELD
;
579 ci
->extra
= savestack(L
, ci
->func
); /* save current 'func' */
580 if (isLua(ci
)) { /* inside a hook? */
581 api_check(L
, k
== NULL
, "hooks cannot continue after yielding");
584 if ((ci
->u
.c
.k
= k
) != NULL
) /* is there a continuation? */
585 ci
->u
.c
.ctx
= ctx
; /* save context */
586 ci
->func
= L
->top
- nresults
- 1; /* protect stack below results */
587 luaD_throw(L
, LUA_YIELD
);
589 lua_assert(ci
->callstatus
& CIST_HOOKED
); /* must be inside a hook */
591 return 0; /* return to 'luaD_hook' */
595 int luaD_pcall (lua_State
*L
, Pfunc func
, void *u
,
596 ptrdiff_t old_top
, ptrdiff_t ef
) {
598 CallInfo
*old_ci
= L
->ci
;
599 lu_byte old_allowhooks
= L
->allowhook
;
600 unsigned short old_nny
= L
->nny
;
601 ptrdiff_t old_errfunc
= L
->errfunc
;
603 status
= luaD_rawrunprotected(L
, func
, u
);
604 if (status
!= LUA_OK
) { /* an error occurred? */
605 StkId oldtop
= restorestack(L
, old_top
);
606 luaF_close(L
, oldtop
); /* close possible pending closures */
607 seterrorobj(L
, status
, oldtop
);
609 L
->allowhook
= old_allowhooks
;
613 L
->errfunc
= old_errfunc
;
620 ** Execute a protected parser.
622 struct SParser
{ /* data to `f_parser' */
624 Mbuffer buff
; /* dynamic structure used by the scanner */
625 Dyndata dyd
; /* dynamic structures used by the parser */
631 static void checkmode (lua_State
*L
, const char *mode
, const char *x
) {
632 if (mode
&& strchr(mode
, x
[0]) == NULL
) {
634 "attempt to load a %s chunk (mode is " LUA_QS
")", x
, mode
);
635 luaD_throw(L
, LUA_ERRSYNTAX
);
640 static void f_parser (lua_State
*L
, void *ud
) {
643 struct SParser
*p
= cast(struct SParser
*, ud
);
644 int c
= zgetc(p
->z
); /* read first character */
645 if (c
== LUA_SIGNATURE
[0]) {
646 checkmode(L
, p
->mode
, "binary");
647 cl
= luaU_undump(L
, p
->z
, &p
->buff
, p
->name
);
650 checkmode(L
, p
->mode
, "text");
651 cl
= luaY_parser(L
, p
->z
, &p
->buff
, &p
->dyd
, p
->name
, c
);
653 lua_assert(cl
->l
.nupvalues
== cl
->l
.p
->sizeupvalues
);
654 for (i
= 0; i
< cl
->l
.nupvalues
; i
++) { /* initialize upvalues */
655 UpVal
*up
= luaF_newupval(L
);
656 cl
->l
.upvals
[i
] = up
;
657 luaC_objbarrier(L
, cl
, up
);
662 int luaD_protectedparser (lua_State
*L
, ZIO
*z
, const char *name
,
666 L
->nny
++; /* cannot yield during parsing */
667 p
.z
= z
; p
.name
= name
; p
.mode
= mode
;
668 p
.dyd
.actvar
.arr
= NULL
; p
.dyd
.actvar
.size
= 0;
669 p
.dyd
.gt
.arr
= NULL
; p
.dyd
.gt
.size
= 0;
670 p
.dyd
.label
.arr
= NULL
; p
.dyd
.label
.size
= 0;
671 luaZ_initbuffer(L
, &p
.buff
);
672 status
= luaD_pcall(L
, f_parser
, &p
, savestack(L
, L
->top
), L
->errfunc
);
673 luaZ_freebuffer(L
, &p
.buff
);
674 luaM_freearray(L
, p
.dyd
.actvar
.arr
, p
.dyd
.actvar
.size
);
675 luaM_freearray(L
, p
.dyd
.gt
.arr
, p
.dyd
.gt
.size
);
676 luaM_freearray(L
, p
.dyd
.label
.arr
, p
.dyd
.label
.size
);