1 /* BEGIN CSTYLED */
2 /*
3 ** $Id: ldo.c,v 2.108.1.3 2013/11/08 18:22:50 roberto Exp $
4 ** Stack and Call structure of Lua
5 ** See Copyright Notice in lua.h
6 */
7
8
9 #define ldo_c
10 #define LUA_CORE
11
12 #include <sys/lua/lua.h>
13
14 #include "lapi.h"
15 #include "ldebug.h"
16 #include "ldo.h"
17 #include "lfunc.h"
18 #include "lgc.h"
19 #include "lmem.h"
20 #include "lobject.h"
21 #include "lopcodes.h"
22 #include "lparser.h"
23 #include "lstate.h"
24 #include "lstring.h"
25 #include "ltable.h"
26 #include "ltm.h"
27 #include "lvm.h"
28 #include "lzio.h"
29
30
31
32 /* Return the number of bytes available on the stack. */
33 #if defined (_KERNEL) && defined(__linux__)
34 #include <asm/current.h>
stack_remaining(void)35 static intptr_t stack_remaining(void) {
36 intptr_t local;
37 local = (intptr_t)&local - (intptr_t)current->stack;
38 return local;
39 }
40 #elif defined (_KERNEL) && defined(__FreeBSD__)
41 #include <sys/pcpu.h>
stack_remaining(void)42 static intptr_t stack_remaining(void) {
43 intptr_t local;
44 local = (intptr_t)&local - (intptr_t)curthread->td_kstack;
45 return local;
46 }
47 #else
stack_remaining(void)48 static intptr_t stack_remaining(void) {
49 return INTPTR_MAX;
50 }
51 #endif
52
53 /*
54 ** {======================================================
55 ** Error-recovery functions
56 ** =======================================================
57 */
58
59 /*
60 ** LUAI_THROW/LUAI_TRY define how Lua does exception handling. By
61 ** default, Lua handles errors with exceptions when compiling as
62 ** C++ code, with _longjmp/_setjmp when asked to use them, and with
63 ** longjmp/setjmp otherwise.
64 */
65 #if !defined(LUAI_THROW)
66
67 #ifdef _KERNEL
68
69 #ifdef __linux__
70 #if defined(__i386__)
71 #define JMP_BUF_CNT 6
72 #elif defined(__x86_64__)
73 #define JMP_BUF_CNT 8
74 #elif defined(__sparc__) && defined(__arch64__)
75 #define JMP_BUF_CNT 6
76 #elif defined(__powerpc__)
77 #define JMP_BUF_CNT 26
78 #elif defined(__aarch64__)
79 #define JMP_BUF_CNT 64
80 #elif defined(__arm__)
81 #define JMP_BUF_CNT 65
82 #elif defined(__mips__)
83 #define JMP_BUF_CNT 12
84 #elif defined(__s390x__)
85 #define JMP_BUF_CNT 18
86 #elif defined(__riscv)
87 #define JMP_BUF_CNT 64
88 #else
89 #define JMP_BUF_CNT 1
90 #endif
91
92 typedef struct _label_t { long long unsigned val[JMP_BUF_CNT]; } label_t;
93
94 int setjmp(label_t *) __attribute__ ((__nothrow__));
95 extern void longjmp(label_t *) __attribute__((__noreturn__));
96
97 #define LUAI_THROW(L,c) longjmp(&(c)->b)
98 #define LUAI_TRY(L,c,a) if (setjmp(&(c)->b) == 0) { a }
99 #define luai_jmpbuf label_t
100
101 /* unsupported arches will build but not be able to run lua programs */
102 #if JMP_BUF_CNT == 1
setjmp(label_t * buf)103 int setjmp (label_t *buf) {
104 return 1;
105 }
106
longjmp(label_t * buf)107 void longjmp (label_t * buf) {
108 for (;;);
109 }
110 #endif
111 #else
112 #define LUAI_THROW(L,c) longjmp((c)->b, 1)
113 #define LUAI_TRY(L,c,a) if (setjmp((c)->b) == 0) { a }
114 #define luai_jmpbuf jmp_buf
115 #endif
116
117 #else /* _KERNEL */
118
119 #if defined(__cplusplus) && !defined(LUA_USE_LONGJMP)
120 /* C++ exceptions */
121 #define LUAI_THROW(L,c) throw(c)
122 #define LUAI_TRY(L,c,a) \
123 try { a } catch(...) { if ((c)->status == 0) (c)->status = -1; }
124 #define luai_jmpbuf int /* dummy variable */
125
126 #elif defined(LUA_USE_ULONGJMP)
127 /* in Unix, try _longjmp/_setjmp (more efficient) */
128 #define LUAI_THROW(L,c) _longjmp((c)->b, 1)
129 #define LUAI_TRY(L,c,a) if (_setjmp((c)->b) == 0) { a }
130 #define luai_jmpbuf jmp_buf
131
132 #else
133 /* default handling with long jumps */
134 #define LUAI_THROW(L,c) longjmp((c)->b, 1)
135 #define LUAI_TRY(L,c,a) if (setjmp((c)->b) == 0) { a }
136 #define luai_jmpbuf jmp_buf
137
138 #endif
139
140 #endif /* _KERNEL */
141
142 #endif /* LUAI_THROW */
143
144
145 /* chain list of long jump buffers */
146 struct lua_longjmp {
147 struct lua_longjmp *previous;
148 luai_jmpbuf b;
149 volatile int status; /* error code */
150 };
151
152
seterrorobj(lua_State * L,int errcode,StkId oldtop)153 static void seterrorobj (lua_State *L, int errcode, StkId oldtop) {
154 switch (errcode) {
155 case LUA_ERRMEM: { /* memory error? */
156 setsvalue2s(L, oldtop, G(L)->memerrmsg); /* reuse preregistered msg. */
157 break;
158 }
159 case LUA_ERRERR: {
160 setsvalue2s(L, oldtop, luaS_newliteral(L, "error in error handling"));
161 break;
162 }
163 default: {
164 setobjs2s(L, oldtop, L->top - 1); /* error message on current top */
165 break;
166 }
167 }
168 L->top = oldtop + 1;
169 }
170
171 /*
172 * Silence infinite recursion warning which was added to -Wall in gcc 12.1
173 */
174 #if defined(__GNUC__) && !defined(__clang__) && \
175 defined(HAVE_KERNEL_INFINITE_RECURSION)
176 #pragma GCC diagnostic push
177 #pragma GCC diagnostic ignored "-Winfinite-recursion"
178 #endif
179
luaD_throw(lua_State * L,int errcode)180 l_noret luaD_throw (lua_State *L, int errcode) {
181 if (L->errorJmp) { /* thread has an error handler? */
182 L->errorJmp->status = errcode; /* set status */
183 LUAI_THROW(L, L->errorJmp); /* jump to it */
184 }
185 else { /* thread has no error handler */
186 L->status = cast_byte(errcode); /* mark it as dead */
187 if (G(L)->mainthread->errorJmp) { /* main thread has a handler? */
188 setobjs2s(L, G(L)->mainthread->top++, L->top - 1); /* copy error obj. */
189 luaD_throw(G(L)->mainthread, errcode); /* re-throw in main thread */
190 }
191 else { /* no handler at all; abort */
192 if (G(L)->panic) { /* panic function? */
193 lua_unlock(L);
194 G(L)->panic(L); /* call it (last chance to jump out) */
195 }
196 panic("no error handler");
197 }
198 }
199 }
200
201 #if defined(__GNUC__) && !defined(__clang__) && \
202 defined(HAVE_INFINITE_RECURSION)
203 #pragma GCC diagnostic pop
204 #endif
205
206
luaD_rawrunprotected(lua_State * L,Pfunc f,void * ud)207 int luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud) {
208 unsigned short oldnCcalls = L->nCcalls;
209 struct lua_longjmp lj;
210 lj.status = LUA_OK;
211 lj.previous = L->errorJmp; /* chain new error handler */
212 L->errorJmp = &lj;
213 LUAI_TRY(L, &lj,
214 (*f)(L, ud);
215 );
216 L->errorJmp = lj.previous; /* restore old error handler */
217 L->nCcalls = oldnCcalls;
218 return lj.status;
219 }
220
221 /* }====================================================== */
222
223
correctstack(lua_State * L,TValue * oldstack)224 static void correctstack (lua_State *L, TValue *oldstack) {
225 CallInfo *ci;
226 GCObject *up;
227 L->top = (L->top - oldstack) + L->stack;
228 for (up = L->openupval; up != NULL; up = up->gch.next)
229 gco2uv(up)->v = (gco2uv(up)->v - oldstack) + L->stack;
230 for (ci = L->ci; ci != NULL; ci = ci->previous) {
231 ci->top = (ci->top - oldstack) + L->stack;
232 ci->func = (ci->func - oldstack) + L->stack;
233 if (isLua(ci))
234 ci->u.l.base = (ci->u.l.base - oldstack) + L->stack;
235 }
236 }
237
238
239 /* some space for error handling */
240 #define ERRORSTACKSIZE (LUAI_MAXSTACK + 200)
241
242
luaD_reallocstack(lua_State * L,int newsize)243 void luaD_reallocstack (lua_State *L, int newsize) {
244 TValue *oldstack = L->stack;
245 int lim = L->stacksize;
246 lua_assert(newsize <= LUAI_MAXSTACK || newsize == ERRORSTACKSIZE);
247 lua_assert(L->stack_last - L->stack == L->stacksize - EXTRA_STACK);
248 luaM_reallocvector(L, L->stack, L->stacksize, newsize, TValue);
249 for (; lim < newsize; lim++)
250 setnilvalue(L->stack + lim); /* erase new segment */
251 L->stacksize = newsize;
252 L->stack_last = L->stack + newsize - EXTRA_STACK;
253 correctstack(L, oldstack);
254 }
255
256
luaD_growstack(lua_State * L,int n)257 void luaD_growstack (lua_State *L, int n) {
258 int size = L->stacksize;
259 if (size > LUAI_MAXSTACK) /* error after extra size? */
260 luaD_throw(L, LUA_ERRERR);
261 else {
262 int needed = cast_int(L->top - L->stack) + n + EXTRA_STACK;
263 int newsize = 2 * size;
264 if (newsize > LUAI_MAXSTACK) newsize = LUAI_MAXSTACK;
265 if (newsize < needed) newsize = needed;
266 if (newsize > LUAI_MAXSTACK) { /* stack overflow? */
267 luaD_reallocstack(L, ERRORSTACKSIZE);
268 luaG_runerror(L, "stack overflow");
269 }
270 else
271 luaD_reallocstack(L, newsize);
272 }
273 }
274
275
stackinuse(lua_State * L)276 static int stackinuse (lua_State *L) {
277 CallInfo *ci;
278 StkId lim = L->top;
279 for (ci = L->ci; ci != NULL; ci = ci->previous) {
280 lua_assert(ci->top <= L->stack_last);
281 if (lim < ci->top) lim = ci->top;
282 }
283 return cast_int(lim - L->stack) + 1; /* part of stack in use */
284 }
285
286
luaD_shrinkstack(lua_State * L)287 void luaD_shrinkstack (lua_State *L) {
288 int inuse = stackinuse(L);
289 int goodsize = inuse + (inuse / 8) + 2*EXTRA_STACK;
290 if (goodsize > LUAI_MAXSTACK) goodsize = LUAI_MAXSTACK;
291 if (inuse > LUAI_MAXSTACK || /* handling stack overflow? */
292 goodsize >= L->stacksize) /* would grow instead of shrink? */
293 condmovestack(L); /* don't change stack (change only for debugging) */
294 else
295 luaD_reallocstack(L, goodsize); /* shrink it */
296 }
297
298
luaD_hook(lua_State * L,int event,int line)299 void luaD_hook (lua_State *L, int event, int line) {
300 lua_Hook hook = L->hook;
301 if (hook && L->allowhook) {
302 CallInfo *ci = L->ci;
303 ptrdiff_t top = savestack(L, L->top);
304 ptrdiff_t ci_top = savestack(L, ci->top);
305 lua_Debug ar;
306 ar.event = event;
307 ar.currentline = line;
308 ar.i_ci = ci;
309 luaD_checkstack(L, LUA_MINSTACK); /* ensure minimum stack size */
310 ci->top = L->top + LUA_MINSTACK;
311 lua_assert(ci->top <= L->stack_last);
312 L->allowhook = 0; /* cannot call hooks inside a hook */
313 ci->callstatus |= CIST_HOOKED;
314 lua_unlock(L);
315 (*hook)(L, &ar);
316 lua_lock(L);
317 lua_assert(!L->allowhook);
318 L->allowhook = 1;
319 ci->top = restorestack(L, ci_top);
320 L->top = restorestack(L, top);
321 ci->callstatus &= ~CIST_HOOKED;
322 }
323 }
324
325
callhook(lua_State * L,CallInfo * ci)326 static void callhook (lua_State *L, CallInfo *ci) {
327 int hook = LUA_HOOKCALL;
328 ci->u.l.savedpc++; /* hooks assume 'pc' is already incremented */
329 if (isLua(ci->previous) &&
330 GET_OPCODE(*(ci->previous->u.l.savedpc - 1)) == OP_TAILCALL) {
331 ci->callstatus |= CIST_TAIL;
332 hook = LUA_HOOKTAILCALL;
333 }
334 luaD_hook(L, hook, -1);
335 ci->u.l.savedpc--; /* correct 'pc' */
336 }
337
338
adjust_varargs(lua_State * L,Proto * p,int actual)339 static StkId adjust_varargs (lua_State *L, Proto *p, int actual) {
340 int i;
341 int nfixargs = p->numparams;
342 StkId base, fixed;
343 lua_assert(actual >= nfixargs);
344 /* move fixed parameters to final position */
345 luaD_checkstack(L, p->maxstacksize); /* check again for new 'base' */
346 fixed = L->top - actual; /* first fixed argument */
347 base = L->top; /* final position of first argument */
348 for (i=0; i<nfixargs; i++) {
349 setobjs2s(L, L->top++, fixed + i);
350 setnilvalue(fixed + i);
351 }
352 return base;
353 }
354
355
tryfuncTM(lua_State * L,StkId func)356 static StkId tryfuncTM (lua_State *L, StkId func) {
357 const TValue *tm = luaT_gettmbyobj(L, func, TM_CALL);
358 StkId p;
359 ptrdiff_t funcr = savestack(L, func);
360 if (!ttisfunction(tm))
361 luaG_typeerror(L, func, "call");
362 /* Open a hole inside the stack at `func' */
363 for (p = L->top; p > func; p--) setobjs2s(L, p, p-1);
364 incr_top(L);
365 func = restorestack(L, funcr); /* previous call may change stack */
366 setobj2s(L, func, tm); /* tag method is the new function to be called */
367 return func;
368 }
369
370
371
372 #define next_ci(L) (L->ci = (L->ci->next ? L->ci->next : luaE_extendCI(L)))
373
374
375 /*
376 ** returns true if function has been executed (C function)
377 */
luaD_precall(lua_State * L,StkId func,int nresults)378 int luaD_precall (lua_State *L, StkId func, int nresults) {
379 lua_CFunction f;
380 CallInfo *ci;
381 int n; /* number of arguments (Lua) or returns (C) */
382 ptrdiff_t funcr = savestack(L, func);
383 switch (ttype(func)) {
384 case LUA_TLCF: /* light C function */
385 f = fvalue(func);
386 goto Cfunc;
387 case LUA_TCCL: { /* C closure */
388 f = clCvalue(func)->f;
389 Cfunc:
390 luaD_checkstack(L, LUA_MINSTACK); /* ensure minimum stack size */
391 ci = next_ci(L); /* now 'enter' new function */
392 ci->nresults = nresults;
393 ci->func = restorestack(L, funcr);
394 ci->top = L->top + LUA_MINSTACK;
395 lua_assert(ci->top <= L->stack_last);
396 ci->callstatus = 0;
397 luaC_checkGC(L); /* stack grow uses memory */
398 if (L->hookmask & LUA_MASKCALL)
399 luaD_hook(L, LUA_HOOKCALL, -1);
400 lua_unlock(L);
401 n = (*f)(L); /* do the actual call */
402 lua_lock(L);
403 api_checknelems(L, n);
404 luaD_poscall(L, L->top - n);
405 return 1;
406 }
407 case LUA_TLCL: { /* Lua function: prepare its call */
408 StkId base;
409 Proto *p = clLvalue(func)->p;
410 n = cast_int(L->top - func) - 1; /* number of real arguments */
411 luaD_checkstack(L, p->maxstacksize + p->numparams);
412 for (; n < p->numparams; n++)
413 setnilvalue(L->top++); /* complete missing arguments */
414 if (!p->is_vararg) {
415 func = restorestack(L, funcr);
416 base = func + 1;
417 }
418 else {
419 base = adjust_varargs(L, p, n);
420 func = restorestack(L, funcr); /* previous call can change stack */
421 }
422 ci = next_ci(L); /* now 'enter' new function */
423 ci->nresults = nresults;
424 ci->func = func;
425 ci->u.l.base = base;
426 ci->top = base + p->maxstacksize;
427 lua_assert(ci->top <= L->stack_last);
428 ci->u.l.savedpc = p->code; /* starting point */
429 ci->callstatus = CIST_LUA;
430 L->top = ci->top;
431 luaC_checkGC(L); /* stack grow uses memory */
432 if (L->hookmask & LUA_MASKCALL)
433 callhook(L, ci);
434 return 0;
435 }
436 default: { /* not a function */
437 func = tryfuncTM(L, func); /* retry with 'function' tag method */
438 return luaD_precall(L, func, nresults); /* now it must be a function */
439 }
440 }
441 }
442
443
luaD_poscall(lua_State * L,StkId firstResult)444 int luaD_poscall (lua_State *L, StkId firstResult) {
445 StkId res;
446 int wanted, i;
447 CallInfo *ci = L->ci;
448 if (L->hookmask & (LUA_MASKRET | LUA_MASKLINE)) {
449 if (L->hookmask & LUA_MASKRET) {
450 ptrdiff_t fr = savestack(L, firstResult); /* hook may change stack */
451 luaD_hook(L, LUA_HOOKRET, -1);
452 firstResult = restorestack(L, fr);
453 }
454 L->oldpc = ci->previous->u.l.savedpc; /* 'oldpc' for caller function */
455 }
456 res = ci->func; /* res == final position of 1st result */
457 wanted = ci->nresults;
458 L->ci = ci = ci->previous; /* back to caller */
459 /* move results to correct place */
460 for (i = wanted; i != 0 && firstResult < L->top; i--)
461 setobjs2s(L, res++, firstResult++);
462 while (i-- > 0)
463 setnilvalue(res++);
464 L->top = res;
465 return (wanted - LUA_MULTRET); /* 0 iff wanted == LUA_MULTRET */
466 }
467
468
469 /*
470 ** Call a function (C or Lua). The function to be called is at *func.
471 ** The arguments are on the stack, right after the function.
472 ** When returns, all the results are on the stack, starting at the original
473 ** function position.
474 */
luaD_call(lua_State * L,StkId func,int nResults,int allowyield)475 void luaD_call (lua_State *L, StkId func, int nResults, int allowyield) {
476 if (++L->nCcalls >= LUAI_MAXCCALLS) {
477 if (L->nCcalls == LUAI_MAXCCALLS)
478 luaG_runerror(L, "C stack overflow");
479 else if (L->nCcalls >= (LUAI_MAXCCALLS + (LUAI_MAXCCALLS>>3)))
480 luaD_throw(L, LUA_ERRERR); /* error while handling stack error */
481 }
482 intptr_t remaining = stack_remaining();
483 if (L->runerror == 0 && remaining < LUAI_MINCSTACK)
484 luaG_runerror(L, "C stack overflow");
485 if (L->runerror != 0 && remaining < LUAI_MINCSTACK / 2)
486 luaD_throw(L, LUA_ERRERR); /* error while handling stack error */
487 if (!allowyield) L->nny++;
488 if (!luaD_precall(L, func, nResults)) /* is a Lua function? */
489 luaV_execute(L); /* call it */
490 if (!allowyield) L->nny--;
491 L->nCcalls--;
492 }
493
494
finishCcall(lua_State * L)495 static void finishCcall (lua_State *L) {
496 CallInfo *ci = L->ci;
497 int n;
498 lua_assert(ci->u.c.k != NULL); /* must have a continuation */
499 lua_assert(L->nny == 0);
500 if (ci->callstatus & CIST_YPCALL) { /* was inside a pcall? */
501 ci->callstatus &= ~CIST_YPCALL; /* finish 'lua_pcall' */
502 L->errfunc = ci->u.c.old_errfunc;
503 }
504 /* finish 'lua_callk'/'lua_pcall' */
505 adjustresults(L, ci->nresults);
506 /* call continuation function */
507 if (!(ci->callstatus & CIST_STAT)) /* no call status? */
508 ci->u.c.status = LUA_YIELD; /* 'default' status */
509 lua_assert(ci->u.c.status != LUA_OK);
510 ci->callstatus = (ci->callstatus & ~(CIST_YPCALL | CIST_STAT)) | CIST_YIELDED;
511 lua_unlock(L);
512 n = (*ci->u.c.k)(L);
513 lua_lock(L);
514 api_checknelems(L, n);
515 /* finish 'luaD_precall' */
516 luaD_poscall(L, L->top - n);
517 }
518
519
unroll(lua_State * L,void * ud)520 static void unroll (lua_State *L, void *ud) {
521 UNUSED(ud);
522 for (;;) {
523 if (L->ci == &L->base_ci) /* stack is empty? */
524 return; /* coroutine finished normally */
525 if (!isLua(L->ci)) /* C function? */
526 finishCcall(L);
527 else { /* Lua function */
528 luaV_finishOp(L); /* finish interrupted instruction */
529 luaV_execute(L); /* execute down to higher C 'boundary' */
530 }
531 }
532 }
533
534
535 /*
536 ** check whether thread has a suspended protected call
537 */
findpcall(lua_State * L)538 static CallInfo *findpcall (lua_State *L) {
539 CallInfo *ci;
540 for (ci = L->ci; ci != NULL; ci = ci->previous) { /* search for a pcall */
541 if (ci->callstatus & CIST_YPCALL)
542 return ci;
543 }
544 return NULL; /* no pending pcall */
545 }
546
547
recover(lua_State * L,int status)548 static int recover (lua_State *L, int status) {
549 StkId oldtop;
550 CallInfo *ci = findpcall(L);
551 if (ci == NULL) return 0; /* no recovery point */
552 /* "finish" luaD_pcall */
553 oldtop = restorestack(L, ci->extra);
554 luaF_close(L, oldtop);
555 seterrorobj(L, status, oldtop);
556 L->ci = ci;
557 L->allowhook = ci->u.c.old_allowhook;
558 L->nny = 0; /* should be zero to be yieldable */
559 luaD_shrinkstack(L);
560 L->errfunc = ci->u.c.old_errfunc;
561 ci->callstatus |= CIST_STAT; /* call has error status */
562 ci->u.c.status = status; /* (here it is) */
563 return 1; /* continue running the coroutine */
564 }
565
566
567 /*
568 ** signal an error in the call to 'resume', not in the execution of the
569 ** coroutine itself. (Such errors should not be handled by any coroutine
570 ** error handler and should not kill the coroutine.)
571 */
resume_error(lua_State * L,const char * msg,StkId firstArg)572 static l_noret resume_error (lua_State *L, const char *msg, StkId firstArg) {
573 L->top = firstArg; /* remove args from the stack */
574 setsvalue2s(L, L->top, luaS_new(L, msg)); /* push error message */
575 api_incr_top(L);
576 luaD_throw(L, -1); /* jump back to 'lua_resume' */
577 }
578
579
580 /*
581 ** do the work for 'lua_resume' in protected mode
582 */
resume_cb(lua_State * L,void * ud)583 static void resume_cb (lua_State *L, void *ud) {
584 int nCcalls = L->nCcalls;
585 StkId firstArg = cast(StkId, ud);
586 CallInfo *ci = L->ci;
587 if (nCcalls >= LUAI_MAXCCALLS)
588 resume_error(L, "C stack overflow", firstArg);
589 if (L->status == LUA_OK) { /* may be starting a coroutine */
590 if (ci != &L->base_ci) /* not in base level? */
591 resume_error(L, "cannot resume non-suspended coroutine", firstArg);
592 /* coroutine is in base level; start running it */
593 if (!luaD_precall(L, firstArg - 1, LUA_MULTRET)) /* Lua function? */
594 luaV_execute(L); /* call it */
595 }
596 else if (L->status != LUA_YIELD)
597 resume_error(L, "cannot resume dead coroutine", firstArg);
598 else { /* resuming from previous yield */
599 L->status = LUA_OK;
600 ci->func = restorestack(L, ci->extra);
601 if (isLua(ci)) /* yielded inside a hook? */
602 luaV_execute(L); /* just continue running Lua code */
603 else { /* 'common' yield */
604 if (ci->u.c.k != NULL) { /* does it have a continuation? */
605 int n;
606 ci->u.c.status = LUA_YIELD; /* 'default' status */
607 ci->callstatus |= CIST_YIELDED;
608 lua_unlock(L);
609 n = (*ci->u.c.k)(L); /* call continuation */
610 lua_lock(L);
611 api_checknelems(L, n);
612 firstArg = L->top - n; /* yield results come from continuation */
613 }
614 luaD_poscall(L, firstArg); /* finish 'luaD_precall' */
615 }
616 unroll(L, NULL);
617 }
618 lua_assert(nCcalls == L->nCcalls);
619 }
620
621
lua_resume(lua_State * L,lua_State * from,int nargs)622 LUA_API int lua_resume (lua_State *L, lua_State *from, int nargs) {
623 int status;
624 int oldnny = L->nny; /* save 'nny' */
625 lua_lock(L);
626 luai_userstateresume(L, nargs);
627 L->nCcalls = (from) ? from->nCcalls + 1 : 1;
628 L->nny = 0; /* allow yields */
629 api_checknelems(L, (L->status == LUA_OK) ? nargs + 1 : nargs);
630 status = luaD_rawrunprotected(L, resume_cb, L->top - nargs);
631 if (status == -1) /* error calling 'lua_resume'? */
632 status = LUA_ERRRUN;
633 else { /* yield or regular error */
634 while (status != LUA_OK && status != LUA_YIELD) { /* error? */
635 if (recover(L, status)) /* recover point? */
636 status = luaD_rawrunprotected(L, unroll, NULL); /* run continuation */
637 else { /* unrecoverable error */
638 L->status = cast_byte(status); /* mark thread as `dead' */
639 seterrorobj(L, status, L->top);
640 L->ci->top = L->top;
641 break;
642 }
643 }
644 lua_assert(status == L->status);
645 }
646 L->nny = oldnny; /* restore 'nny' */
647 L->nCcalls--;
648 lua_assert(L->nCcalls == ((from) ? from->nCcalls : 0));
649 lua_unlock(L);
650 return status;
651 }
652
653
lua_yieldk(lua_State * L,int nresults,int ctx,lua_CFunction k)654 LUA_API int lua_yieldk (lua_State *L, int nresults, int ctx, lua_CFunction k) {
655 CallInfo *ci = L->ci;
656 luai_userstateyield(L, nresults);
657 lua_lock(L);
658 api_checknelems(L, nresults);
659 if (L->nny > 0) {
660 if (L != G(L)->mainthread)
661 luaG_runerror(L, "attempt to yield across a C-call boundary");
662 else
663 luaG_runerror(L, "attempt to yield from outside a coroutine");
664 }
665 L->status = LUA_YIELD;
666 ci->extra = savestack(L, ci->func); /* save current 'func' */
667 if (isLua(ci)) { /* inside a hook? */
668 api_check(L, k == NULL, "hooks cannot continue after yielding");
669 }
670 else {
671 if ((ci->u.c.k = k) != NULL) /* is there a continuation? */
672 ci->u.c.ctx = ctx; /* save context */
673 ci->func = L->top - nresults - 1; /* protect stack below results */
674 luaD_throw(L, LUA_YIELD);
675 }
676 lua_assert(ci->callstatus & CIST_HOOKED); /* must be inside a hook */
677 lua_unlock(L);
678 return 0; /* return to 'luaD_hook' */
679 }
680
681
luaD_pcall(lua_State * L,Pfunc func,void * u,ptrdiff_t old_top,ptrdiff_t ef)682 int luaD_pcall (lua_State *L, Pfunc func, void *u,
683 ptrdiff_t old_top, ptrdiff_t ef) {
684 int status;
685 CallInfo *old_ci = L->ci;
686 lu_byte old_allowhooks = L->allowhook;
687 unsigned short old_nny = L->nny;
688 ptrdiff_t old_errfunc = L->errfunc;
689 L->errfunc = ef;
690 status = luaD_rawrunprotected(L, func, u);
691 if (status != LUA_OK) { /* an error occurred? */
692 StkId oldtop = restorestack(L, old_top);
693 luaF_close(L, oldtop); /* close possible pending closures */
694 seterrorobj(L, status, oldtop);
695 L->ci = old_ci;
696 L->allowhook = old_allowhooks;
697 L->nny = old_nny;
698 luaD_shrinkstack(L);
699 }
700 L->errfunc = old_errfunc;
701 return status;
702 }
703
704
705
706 /*
707 ** Execute a protected parser.
708 */
709 struct SParser { /* data to `f_parser' */
710 ZIO *z;
711 Mbuffer buff; /* dynamic structure used by the scanner */
712 Dyndata dyd; /* dynamic structures used by the parser */
713 const char *mode;
714 const char *name;
715 };
716
717
checkmode(lua_State * L,const char * mode,const char * x)718 static void checkmode (lua_State *L, const char *mode, const char *x) {
719 if (mode && strchr(mode, x[0]) == NULL) {
720 luaO_pushfstring(L,
721 "attempt to load a %s chunk (mode is " LUA_QS ")", x, mode);
722 luaD_throw(L, LUA_ERRSYNTAX);
723 }
724 }
725
726
f_parser(lua_State * L,void * ud)727 static void f_parser (lua_State *L, void *ud) {
728 int i;
729 Closure *cl;
730 struct SParser *p = cast(struct SParser *, ud);
731 int c = zgetc(p->z); /* read first character */
732 lua_assert(c != LUA_SIGNATURE[0]); /* binary not supported */
733 checkmode(L, p->mode, "text");
734 cl = luaY_parser(L, p->z, &p->buff, &p->dyd, p->name, c);
735 lua_assert(cl->l.nupvalues == cl->l.p->sizeupvalues);
736 for (i = 0; i < cl->l.nupvalues; i++) { /* initialize upvalues */
737 UpVal *up = luaF_newupval(L);
738 cl->l.upvals[i] = up;
739 luaC_objbarrier(L, cl, up);
740 }
741 }
742
743
luaD_protectedparser(lua_State * L,ZIO * z,const char * name,const char * mode)744 int luaD_protectedparser (lua_State *L, ZIO *z, const char *name,
745 const char *mode) {
746 struct SParser p;
747 int status;
748 L->nny++; /* cannot yield during parsing */
749 p.z = z; p.name = name; p.mode = mode;
750 p.dyd.actvar.arr = NULL; p.dyd.actvar.size = 0;
751 p.dyd.gt.arr = NULL; p.dyd.gt.size = 0;
752 p.dyd.label.arr = NULL; p.dyd.label.size = 0;
753 luaZ_initbuffer(L, &p.buff);
754 status = luaD_pcall(L, f_parser, &p, savestack(L, L->top), L->errfunc);
755 luaZ_freebuffer(L, &p.buff);
756 luaM_freearray(L, p.dyd.actvar.arr, p.dyd.actvar.size);
757 luaM_freearray(L, p.dyd.gt.arr, p.dyd.gt.size);
758 luaM_freearray(L, p.dyd.label.arr, p.dyd.label.size);
759 L->nny--;
760 return status;
761 }
762 /* END CSTYLED */
763