1 /*
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
5 */
6
7
8 #define ldo_c
9 #define LUA_CORE
10
11 #include <sys/lua/lua.h>
12 #include <sys/asm_linkage.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 /* Return the number of bytes available on the stack. */
32 #if defined (_KERNEL) && defined(__linux__)
33 #include <asm/current.h>
stack_remaining(void)34 static intptr_t stack_remaining(void) {
35 intptr_t local;
36 local = (intptr_t)&local - (intptr_t)current->stack;
37 return local;
38 }
39 #elif defined (_KERNEL) && defined(__FreeBSD__)
40 #include <sys/pcpu.h>
stack_remaining(void)41 static intptr_t stack_remaining(void) {
42 intptr_t local;
43 local = (intptr_t)&local - (intptr_t)curthread->td_kstack;
44 return local;
45 }
46 #else
stack_remaining(void)47 static intptr_t stack_remaining(void) {
48 return INTPTR_MAX;
49 }
50 #endif
51
52 /*
53 ** {======================================================
54 ** Error-recovery functions
55 ** =======================================================
56 */
57
58 /*
59 ** LUAI_THROW/LUAI_TRY define how Lua does exception handling. By
60 ** default, Lua handles errors with exceptions when compiling as
61 ** C++ code, with _longjmp/_setjmp when asked to use them, and with
62 ** longjmp/setjmp otherwise.
63 */
64 #if !defined(LUAI_THROW)
65
66 #ifdef _KERNEL
67
68 #ifdef __linux__
69 #if defined(__i386__)
70 #define JMP_BUF_CNT 6
71 #elif defined(__x86_64__)
72 #define JMP_BUF_CNT 8
73 #elif defined(__sparc__) && defined(__arch64__)
74 #define JMP_BUF_CNT 6
75 #elif defined(__powerpc__)
76 #define JMP_BUF_CNT 26
77 #elif defined(__aarch64__)
78 #define JMP_BUF_CNT 64
79 #elif defined(__arm__)
80 #define JMP_BUF_CNT 65
81 #elif defined(__mips__)
82 #define JMP_BUF_CNT 12
83 #elif defined(__s390x__)
84 #define JMP_BUF_CNT 18
85 #elif defined(__riscv)
86 #define JMP_BUF_CNT 64
87 #elif defined(__loongarch_lp64)
88 #define JMP_BUF_CNT 64
89 #else
90 #define JMP_BUF_CNT 1
91 #endif
92
93 typedef struct _label_t { long long unsigned val[JMP_BUF_CNT]; } label_t;
94
95 int ASMABI setjmp(label_t *) __attribute__ ((__nothrow__));
96 extern __attribute__((noreturn)) void ASMABI longjmp(label_t *);
97
98 #define LUAI_THROW(L,c) longjmp(&(c)->b)
99 #define LUAI_TRY(L,c,a) if (setjmp(&(c)->b) == 0) { a }
100 #define luai_jmpbuf label_t
101
102 /* unsupported arches will build but not be able to run lua programs */
103 #if JMP_BUF_CNT == 1
setjmp(label_t * buf)104 int setjmp (label_t *buf) {
105 return 1;
106 }
107
longjmp(label_t * buf)108 void longjmp (label_t * buf) {
109 for (;;);
110 }
111 #endif
112 #else
113 #define LUAI_THROW(L,c) longjmp((c)->b, 1)
114 #define LUAI_TRY(L,c,a) if (setjmp((c)->b) == 0) { a }
115 #define luai_jmpbuf jmp_buf
116 #endif
117
118 #else /* _KERNEL */
119
120 #if defined(__cplusplus) && !defined(LUA_USE_LONGJMP)
121 /* C++ exceptions */
122 #define LUAI_THROW(L,c) throw(c)
123 #define LUAI_TRY(L,c,a) \
124 try { a } catch(...) { if ((c)->status == 0) (c)->status = -1; }
125 #define luai_jmpbuf int /* dummy variable */
126
127 #elif defined(LUA_USE_ULONGJMP)
128 /* in Unix, try _longjmp/_setjmp (more efficient) */
129 #define LUAI_THROW(L,c) _longjmp((c)->b, 1)
130 #define LUAI_TRY(L,c,a) if (_setjmp((c)->b) == 0) { a }
131 #define luai_jmpbuf jmp_buf
132
133 #else
134 /* default handling with long jumps */
135 #define LUAI_THROW(L,c) longjmp((c)->b, 1)
136 #define LUAI_TRY(L,c,a) if (setjmp((c)->b) == 0) { a }
137 #define luai_jmpbuf jmp_buf
138
139 #endif
140
141 #endif /* _KERNEL */
142
143 #endif /* LUAI_THROW */
144
145
146 /* chain list of long jump buffers */
147 struct lua_longjmp {
148 struct lua_longjmp *previous;
149 luai_jmpbuf b;
150 volatile int status; /* error code */
151 };
152
153
seterrorobj(lua_State * L,int errcode,StkId oldtop)154 static void seterrorobj (lua_State *L, int errcode, StkId oldtop) {
155 switch (errcode) {
156 case LUA_ERRMEM: { /* memory error? */
157 setsvalue2s(L, oldtop, G(L)->memerrmsg); /* reuse preregistered msg. */
158 break;
159 }
160 case LUA_ERRERR: {
161 setsvalue2s(L, oldtop, luaS_newliteral(L, "error in error handling"));
162 break;
163 }
164 default: {
165 setobjs2s(L, oldtop, L->top - 1); /* error message on current top */
166 break;
167 }
168 }
169 L->top = oldtop + 1;
170 }
171
172 /*
173 * Silence infinite recursion warning which was added to -Wall in gcc 12.1
174 */
175 #if defined(__GNUC__) && !defined(__clang__) && \
176 defined(HAVE_KERNEL_INFINITE_RECURSION)
177 #pragma GCC diagnostic push
178 #pragma GCC diagnostic ignored "-Winfinite-recursion"
179 #endif
180
luaD_throw(lua_State * L,int errcode)181 l_noret luaD_throw (lua_State *L, int errcode) {
182 if (L->errorJmp) { /* thread has an error handler? */
183 L->errorJmp->status = errcode; /* set status */
184 LUAI_THROW(L, L->errorJmp); /* jump to it */
185 }
186 else { /* thread has no error handler */
187 L->status = cast_byte(errcode); /* mark it as dead */
188 if (G(L)->mainthread->errorJmp) { /* main thread has a handler? */
189 setobjs2s(L, G(L)->mainthread->top++, L->top - 1); /* copy error obj. */
190 luaD_throw(G(L)->mainthread, errcode); /* re-throw in main thread */
191 }
192 else { /* no handler at all; abort */
193 if (G(L)->panic) { /* panic function? */
194 lua_unlock(L);
195 G(L)->panic(L); /* call it (last chance to jump out) */
196 }
197 panic("no error handler");
198 }
199 }
200 }
201
202 #if defined(__GNUC__) && !defined(__clang__) && \
203 defined(HAVE_INFINITE_RECURSION)
204 #pragma GCC diagnostic pop
205 #endif
206
207
luaD_rawrunprotected(lua_State * L,Pfunc f,void * ud)208 int luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud) {
209 unsigned short oldnCcalls = L->nCcalls;
210 struct lua_longjmp lj;
211 lj.status = LUA_OK;
212 lj.previous = L->errorJmp; /* chain new error handler */
213 L->errorJmp = &lj;
214 LUAI_TRY(L, &lj,
215 (*f)(L, ud);
216 );
217 L->errorJmp = lj.previous; /* restore old error handler */
218 L->nCcalls = oldnCcalls;
219 return lj.status;
220 }
221
222 /* }====================================================== */
223
224
correctstack(lua_State * L,TValue * oldstack)225 static void correctstack (lua_State *L, TValue *oldstack) {
226 CallInfo *ci;
227 GCObject *up;
228 L->top = (L->top - oldstack) + L->stack;
229 for (up = L->openupval; up != NULL; up = up->gch.next)
230 gco2uv(up)->v = (gco2uv(up)->v - oldstack) + L->stack;
231 for (ci = L->ci; ci != NULL; ci = ci->previous) {
232 ci->top = (ci->top - oldstack) + L->stack;
233 ci->func = (ci->func - oldstack) + L->stack;
234 if (isLua(ci))
235 ci->u.l.base = (ci->u.l.base - oldstack) + L->stack;
236 }
237 }
238
239
240 /* some space for error handling */
241 #define ERRORSTACKSIZE (LUAI_MAXSTACK + 200)
242
243
luaD_reallocstack(lua_State * L,int newsize)244 void luaD_reallocstack (lua_State *L, int newsize) {
245 TValue *oldstack = L->stack;
246 int lim = L->stacksize;
247 lua_assert(newsize <= LUAI_MAXSTACK || newsize == ERRORSTACKSIZE);
248 lua_assert(L->stack_last - L->stack == L->stacksize - EXTRA_STACK);
249 luaM_reallocvector(L, L->stack, L->stacksize, newsize, TValue);
250 for (; lim < newsize; lim++)
251 setnilvalue(L->stack + lim); /* erase new segment */
252 L->stacksize = newsize;
253 L->stack_last = L->stack + newsize - EXTRA_STACK;
254 correctstack(L, oldstack);
255 }
256
257
luaD_growstack(lua_State * L,int n)258 void luaD_growstack (lua_State *L, int n) {
259 int size = L->stacksize;
260 if (size > LUAI_MAXSTACK) /* error after extra size? */
261 luaD_throw(L, LUA_ERRERR);
262 else {
263 int needed = cast_int(L->top - L->stack) + n + EXTRA_STACK;
264 int newsize = 2 * size;
265 if (newsize > LUAI_MAXSTACK) newsize = LUAI_MAXSTACK;
266 if (newsize < needed) newsize = needed;
267 if (newsize > LUAI_MAXSTACK) { /* stack overflow? */
268 luaD_reallocstack(L, ERRORSTACKSIZE);
269 luaG_runerror(L, "stack overflow");
270 }
271 else
272 luaD_reallocstack(L, newsize);
273 }
274 }
275
276
stackinuse(lua_State * L)277 static int stackinuse (lua_State *L) {
278 CallInfo *ci;
279 StkId lim = L->top;
280 for (ci = L->ci; ci != NULL; ci = ci->previous) {
281 lua_assert(ci->top <= L->stack_last);
282 if (lim < ci->top) lim = ci->top;
283 }
284 return cast_int(lim - L->stack) + 1; /* part of stack in use */
285 }
286
287
luaD_shrinkstack(lua_State * L)288 void luaD_shrinkstack (lua_State *L) {
289 int inuse = stackinuse(L);
290 int goodsize = inuse + (inuse / 8) + 2*EXTRA_STACK;
291 if (goodsize > LUAI_MAXSTACK) goodsize = LUAI_MAXSTACK;
292 if (inuse > LUAI_MAXSTACK || /* handling stack overflow? */
293 goodsize >= L->stacksize) /* would grow instead of shrink? */
294 condmovestack(L); /* don't change stack (change only for debugging) */
295 else
296 luaD_reallocstack(L, goodsize); /* shrink it */
297 }
298
299
luaD_hook(lua_State * L,int event,int line)300 void luaD_hook (lua_State *L, int event, int line) {
301 lua_Hook hook = L->hook;
302 if (hook && L->allowhook) {
303 CallInfo *ci = L->ci;
304 ptrdiff_t top = savestack(L, L->top);
305 ptrdiff_t ci_top = savestack(L, ci->top);
306 lua_Debug ar;
307 ar.event = event;
308 ar.currentline = line;
309 ar.i_ci = ci;
310 luaD_checkstack(L, LUA_MINSTACK); /* ensure minimum stack size */
311 ci->top = L->top + LUA_MINSTACK;
312 lua_assert(ci->top <= L->stack_last);
313 L->allowhook = 0; /* cannot call hooks inside a hook */
314 ci->callstatus |= CIST_HOOKED;
315 lua_unlock(L);
316 (*hook)(L, &ar);
317 lua_lock(L);
318 lua_assert(!L->allowhook);
319 L->allowhook = 1;
320 ci->top = restorestack(L, ci_top);
321 L->top = restorestack(L, top);
322 ci->callstatus &= ~CIST_HOOKED;
323 }
324 }
325
326
callhook(lua_State * L,CallInfo * ci)327 static void callhook (lua_State *L, CallInfo *ci) {
328 int hook = LUA_HOOKCALL;
329 ci->u.l.savedpc++; /* hooks assume 'pc' is already incremented */
330 if (isLua(ci->previous) &&
331 GET_OPCODE(*(ci->previous->u.l.savedpc - 1)) == OP_TAILCALL) {
332 ci->callstatus |= CIST_TAIL;
333 hook = LUA_HOOKTAILCALL;
334 }
335 luaD_hook(L, hook, -1);
336 ci->u.l.savedpc--; /* correct 'pc' */
337 }
338
339
adjust_varargs(lua_State * L,Proto * p,int actual)340 static StkId adjust_varargs (lua_State *L, Proto *p, int actual) {
341 int i;
342 int nfixargs = p->numparams;
343 StkId base, fixed;
344 lua_assert(actual >= nfixargs);
345 /* move fixed parameters to final position */
346 luaD_checkstack(L, p->maxstacksize); /* check again for new 'base' */
347 fixed = L->top - actual; /* first fixed argument */
348 base = L->top; /* final position of first argument */
349 for (i=0; i<nfixargs; i++) {
350 setobjs2s(L, L->top++, fixed + i);
351 setnilvalue(fixed + i);
352 }
353 return base;
354 }
355
356
tryfuncTM(lua_State * L,StkId func)357 static StkId tryfuncTM (lua_State *L, StkId func) {
358 const TValue *tm = luaT_gettmbyobj(L, func, TM_CALL);
359 StkId p;
360 ptrdiff_t funcr = savestack(L, func);
361 if (!ttisfunction(tm))
362 luaG_typeerror(L, func, "call");
363 /* Open a hole inside the stack at `func' */
364 for (p = L->top; p > func; p--) setobjs2s(L, p, p-1);
365 incr_top(L);
366 func = restorestack(L, funcr); /* previous call may change stack */
367 setobj2s(L, func, tm); /* tag method is the new function to be called */
368 return func;
369 }
370
371
372
373 #define next_ci(L) (L->ci = (L->ci->next ? L->ci->next : luaE_extendCI(L)))
374
375
376 /*
377 ** returns true if function has been executed (C function)
378 */
luaD_precall(lua_State * L,StkId func,int nresults)379 int luaD_precall (lua_State *L, StkId func, int nresults) {
380 lua_CFunction f;
381 CallInfo *ci;
382 int n; /* number of arguments (Lua) or returns (C) */
383 ptrdiff_t funcr = savestack(L, func);
384 switch (ttype(func)) {
385 case LUA_TLCF: /* light C function */
386 f = fvalue(func);
387 goto Cfunc;
388 case LUA_TCCL: { /* C closure */
389 f = clCvalue(func)->f;
390 Cfunc:
391 luaD_checkstack(L, LUA_MINSTACK); /* ensure minimum stack size */
392 ci = next_ci(L); /* now 'enter' new function */
393 ci->nresults = nresults;
394 ci->func = restorestack(L, funcr);
395 ci->top = L->top + LUA_MINSTACK;
396 lua_assert(ci->top <= L->stack_last);
397 ci->callstatus = 0;
398 luaC_checkGC(L); /* stack grow uses memory */
399 if (L->hookmask & LUA_MASKCALL)
400 luaD_hook(L, LUA_HOOKCALL, -1);
401 lua_unlock(L);
402 n = (*f)(L); /* do the actual call */
403 lua_lock(L);
404 api_checknelems(L, n);
405 luaD_poscall(L, L->top - n);
406 return 1;
407 }
408 case LUA_TLCL: { /* Lua function: prepare its call */
409 StkId base;
410 Proto *p = clLvalue(func)->p;
411 n = cast_int(L->top - func) - 1; /* number of real arguments */
412 luaD_checkstack(L, p->maxstacksize + p->numparams);
413 for (; n < p->numparams; n++)
414 setnilvalue(L->top++); /* complete missing arguments */
415 if (!p->is_vararg) {
416 func = restorestack(L, funcr);
417 base = func + 1;
418 }
419 else {
420 base = adjust_varargs(L, p, n);
421 func = restorestack(L, funcr); /* previous call can change stack */
422 }
423 ci = next_ci(L); /* now 'enter' new function */
424 ci->nresults = nresults;
425 ci->func = func;
426 ci->u.l.base = base;
427 ci->top = base + p->maxstacksize;
428 lua_assert(ci->top <= L->stack_last);
429 ci->u.l.savedpc = p->code; /* starting point */
430 ci->callstatus = CIST_LUA;
431 L->top = ci->top;
432 luaC_checkGC(L); /* stack grow uses memory */
433 if (L->hookmask & LUA_MASKCALL)
434 callhook(L, ci);
435 return 0;
436 }
437 default: { /* not a function */
438 func = tryfuncTM(L, func); /* retry with 'function' tag method */
439 return luaD_precall(L, func, nresults); /* now it must be a function */
440 }
441 }
442 }
443
444
luaD_poscall(lua_State * L,StkId firstResult)445 int luaD_poscall (lua_State *L, StkId firstResult) {
446 StkId res;
447 int wanted, i;
448 CallInfo *ci = L->ci;
449 if (L->hookmask & (LUA_MASKRET | LUA_MASKLINE)) {
450 if (L->hookmask & LUA_MASKRET) {
451 ptrdiff_t fr = savestack(L, firstResult); /* hook may change stack */
452 luaD_hook(L, LUA_HOOKRET, -1);
453 firstResult = restorestack(L, fr);
454 }
455 L->oldpc = ci->previous->u.l.savedpc; /* 'oldpc' for caller function */
456 }
457 res = ci->func; /* res == final position of 1st result */
458 wanted = ci->nresults;
459 L->ci = ci->previous; /* back to caller */
460 /* move results to correct place */
461 for (i = wanted; i != 0 && firstResult < L->top; i--)
462 setobjs2s(L, res++, firstResult++);
463 while (i-- > 0)
464 setnilvalue(res++);
465 L->top = res;
466 return (wanted - LUA_MULTRET); /* 0 iff wanted == LUA_MULTRET */
467 }
468
469
470 /*
471 ** Call a function (C or Lua). The function to be called is at *func.
472 ** The arguments are on the stack, right after the function.
473 ** When returns, all the results are on the stack, starting at the original
474 ** function position.
475 */
luaD_call(lua_State * L,StkId func,int nResults,int allowyield)476 void luaD_call (lua_State *L, StkId func, int nResults, int allowyield) {
477 if (++L->nCcalls >= LUAI_MAXCCALLS) {
478 if (L->nCcalls == LUAI_MAXCCALLS)
479 luaG_runerror(L, "C stack overflow");
480 else if (L->nCcalls >= (LUAI_MAXCCALLS + (LUAI_MAXCCALLS>>3)))
481 luaD_throw(L, LUA_ERRERR); /* error while handling stack error */
482 }
483 intptr_t remaining = stack_remaining();
484 if (L->runerror == 0 && remaining < LUAI_MINCSTACK)
485 luaG_runerror(L, "C stack overflow");
486 if (L->runerror != 0 && remaining < LUAI_MINCSTACK / 2)
487 luaD_throw(L, LUA_ERRERR); /* error while handling stack error */
488 if (!allowyield) L->nny++;
489 if (!luaD_precall(L, func, nResults)) /* is a Lua function? */
490 luaV_execute(L); /* call it */
491 if (!allowyield) L->nny--;
492 L->nCcalls--;
493 }
494
495
finishCcall(lua_State * L)496 static void finishCcall (lua_State *L) {
497 CallInfo *ci = L->ci;
498 int n;
499 lua_assert(ci->u.c.k != NULL); /* must have a continuation */
500 lua_assert(L->nny == 0);
501 if (ci->callstatus & CIST_YPCALL) { /* was inside a pcall? */
502 ci->callstatus &= ~CIST_YPCALL; /* finish 'lua_pcall' */
503 L->errfunc = ci->u.c.old_errfunc;
504 }
505 /* finish 'lua_callk'/'lua_pcall' */
506 adjustresults(L, ci->nresults);
507 /* call continuation function */
508 if (!(ci->callstatus & CIST_STAT)) /* no call status? */
509 ci->u.c.status = LUA_YIELD; /* 'default' status */
510 lua_assert(ci->u.c.status != LUA_OK);
511 ci->callstatus = (ci->callstatus & ~(CIST_YPCALL | CIST_STAT)) | CIST_YIELDED;
512 lua_unlock(L);
513 n = (*ci->u.c.k)(L);
514 lua_lock(L);
515 api_checknelems(L, n);
516 /* finish 'luaD_precall' */
517 luaD_poscall(L, L->top - n);
518 }
519
520
unroll(lua_State * L,void * ud)521 static void unroll (lua_State *L, void *ud) {
522 UNUSED(ud);
523 for (;;) {
524 if (L->ci == &L->base_ci) /* stack is empty? */
525 return; /* coroutine finished normally */
526 if (!isLua(L->ci)) /* C function? */
527 finishCcall(L);
528 else { /* Lua function */
529 luaV_finishOp(L); /* finish interrupted instruction */
530 luaV_execute(L); /* execute down to higher C 'boundary' */
531 }
532 }
533 }
534
535
536 /*
537 ** check whether thread has a suspended protected call
538 */
findpcall(lua_State * L)539 static CallInfo *findpcall (lua_State *L) {
540 CallInfo *ci;
541 for (ci = L->ci; ci != NULL; ci = ci->previous) { /* search for a pcall */
542 if (ci->callstatus & CIST_YPCALL)
543 return ci;
544 }
545 return NULL; /* no pending pcall */
546 }
547
548
recover(lua_State * L,int status)549 static int recover (lua_State *L, int status) {
550 StkId oldtop;
551 CallInfo *ci = findpcall(L);
552 if (ci == NULL) return 0; /* no recovery point */
553 /* "finish" luaD_pcall */
554 oldtop = restorestack(L, ci->extra);
555 luaF_close(L, oldtop);
556 seterrorobj(L, status, oldtop);
557 L->ci = ci;
558 L->allowhook = ci->u.c.old_allowhook;
559 L->nny = 0; /* should be zero to be yieldable */
560 luaD_shrinkstack(L);
561 L->errfunc = ci->u.c.old_errfunc;
562 ci->callstatus |= CIST_STAT; /* call has error status */
563 ci->u.c.status = status; /* (here it is) */
564 return 1; /* continue running the coroutine */
565 }
566
567
568 /*
569 ** signal an error in the call to 'resume', not in the execution of the
570 ** coroutine itself. (Such errors should not be handled by any coroutine
571 ** error handler and should not kill the coroutine.)
572 */
resume_error(lua_State * L,const char * msg,StkId firstArg)573 static l_noret resume_error (lua_State *L, const char *msg, StkId firstArg) {
574 L->top = firstArg; /* remove args from the stack */
575 setsvalue2s(L, L->top, luaS_new(L, msg)); /* push error message */
576 api_incr_top(L);
577 luaD_throw(L, -1); /* jump back to 'lua_resume' */
578 }
579
580
581 /*
582 ** do the work for 'lua_resume' in protected mode
583 */
resume_cb(lua_State * L,void * ud)584 static void resume_cb (lua_State *L, void *ud) {
585 int nCcalls = L->nCcalls;
586 StkId firstArg = cast(StkId, ud);
587 CallInfo *ci = L->ci;
588 if (nCcalls >= LUAI_MAXCCALLS)
589 resume_error(L, "C stack overflow", firstArg);
590 if (L->status == LUA_OK) { /* may be starting a coroutine */
591 if (ci != &L->base_ci) /* not in base level? */
592 resume_error(L, "cannot resume non-suspended coroutine", firstArg);
593 /* coroutine is in base level; start running it */
594 if (!luaD_precall(L, firstArg - 1, LUA_MULTRET)) /* Lua function? */
595 luaV_execute(L); /* call it */
596 }
597 else if (L->status != LUA_YIELD)
598 resume_error(L, "cannot resume dead coroutine", firstArg);
599 else { /* resuming from previous yield */
600 L->status = LUA_OK;
601 ci->func = restorestack(L, ci->extra);
602 if (isLua(ci)) /* yielded inside a hook? */
603 luaV_execute(L); /* just continue running Lua code */
604 else { /* 'common' yield */
605 if (ci->u.c.k != NULL) { /* does it have a continuation? */
606 int n;
607 ci->u.c.status = LUA_YIELD; /* 'default' status */
608 ci->callstatus |= CIST_YIELDED;
609 lua_unlock(L);
610 n = (*ci->u.c.k)(L); /* call continuation */
611 lua_lock(L);
612 api_checknelems(L, n);
613 firstArg = L->top - n; /* yield results come from continuation */
614 }
615 luaD_poscall(L, firstArg); /* finish 'luaD_precall' */
616 }
617 unroll(L, NULL);
618 }
619 lua_assert(nCcalls == L->nCcalls);
620 }
621
622
lua_resume(lua_State * L,lua_State * from,int nargs)623 LUA_API int lua_resume (lua_State *L, lua_State *from, int nargs) {
624 int status;
625 int oldnny = L->nny; /* save 'nny' */
626 lua_lock(L);
627 luai_userstateresume(L, nargs);
628 L->nCcalls = (from) ? from->nCcalls + 1 : 1;
629 L->nny = 0; /* allow yields */
630 api_checknelems(L, (L->status == LUA_OK) ? nargs + 1 : nargs);
631 status = luaD_rawrunprotected(L, resume_cb, L->top - nargs);
632 if (status == -1) /* error calling 'lua_resume'? */
633 status = LUA_ERRRUN;
634 else { /* yield or regular error */
635 while (status != LUA_OK && status != LUA_YIELD) { /* error? */
636 if (recover(L, status)) /* recover point? */
637 status = luaD_rawrunprotected(L, unroll, NULL); /* run continuation */
638 else { /* unrecoverable error */
639 L->status = cast_byte(status); /* mark thread as `dead' */
640 seterrorobj(L, status, L->top);
641 L->ci->top = L->top;
642 break;
643 }
644 }
645 lua_assert(status == L->status);
646 }
647 L->nny = oldnny; /* restore 'nny' */
648 L->nCcalls--;
649 lua_assert(L->nCcalls == ((from) ? from->nCcalls : 0));
650 lua_unlock(L);
651 return status;
652 }
653
654
lua_yieldk(lua_State * L,int nresults,int ctx,lua_CFunction k)655 LUA_API int lua_yieldk (lua_State *L, int nresults, int ctx, lua_CFunction k) {
656 CallInfo *ci = L->ci;
657 luai_userstateyield(L, nresults);
658 lua_lock(L);
659 api_checknelems(L, nresults);
660 if (L->nny > 0) {
661 if (L != G(L)->mainthread)
662 luaG_runerror(L, "attempt to yield across a C-call boundary");
663 else
664 luaG_runerror(L, "attempt to yield from outside a coroutine");
665 }
666 L->status = LUA_YIELD;
667 ci->extra = savestack(L, ci->func); /* save current 'func' */
668 if (isLua(ci)) { /* inside a hook? */
669 api_check(L, k == NULL, "hooks cannot continue after yielding");
670 }
671 else {
672 if ((ci->u.c.k = k) != NULL) /* is there a continuation? */
673 ci->u.c.ctx = ctx; /* save context */
674 ci->func = L->top - nresults - 1; /* protect stack below results */
675 luaD_throw(L, LUA_YIELD);
676 }
677 lua_assert(ci->callstatus & CIST_HOOKED); /* must be inside a hook */
678 lua_unlock(L);
679 return 0; /* return to 'luaD_hook' */
680 }
681
682
luaD_pcall(lua_State * L,Pfunc func,void * u,ptrdiff_t old_top,ptrdiff_t ef)683 int luaD_pcall (lua_State *L, Pfunc func, void *u,
684 ptrdiff_t old_top, ptrdiff_t ef) {
685 int status;
686 CallInfo *old_ci = L->ci;
687 lu_byte old_allowhooks = L->allowhook;
688 unsigned short old_nny = L->nny;
689 ptrdiff_t old_errfunc = L->errfunc;
690 L->errfunc = ef;
691 status = luaD_rawrunprotected(L, func, u);
692 if (status != LUA_OK) { /* an error occurred? */
693 StkId oldtop = restorestack(L, old_top);
694 luaF_close(L, oldtop); /* close possible pending closures */
695 seterrorobj(L, status, oldtop);
696 L->ci = old_ci;
697 L->allowhook = old_allowhooks;
698 L->nny = old_nny;
699 luaD_shrinkstack(L);
700 }
701 L->errfunc = old_errfunc;
702 return status;
703 }
704
705
706
707 /*
708 ** Execute a protected parser.
709 */
710 struct SParser { /* data to `f_parser' */
711 ZIO *z;
712 Mbuffer buff; /* dynamic structure used by the scanner */
713 Dyndata dyd; /* dynamic structures used by the parser */
714 const char *mode;
715 const char *name;
716 };
717
718
checkmode(lua_State * L,const char * mode,const char * x)719 static void checkmode (lua_State *L, const char *mode, const char *x) {
720 if (mode && strchr(mode, x[0]) == NULL) {
721 luaO_pushfstring(L,
722 "attempt to load a %s chunk (mode is " LUA_QS ")", x, mode);
723 luaD_throw(L, LUA_ERRSYNTAX);
724 }
725 }
726
727
f_parser(lua_State * L,void * ud)728 static void f_parser (lua_State *L, void *ud) {
729 int i;
730 Closure *cl;
731 struct SParser *p = cast(struct SParser *, ud);
732 int c = zgetc(p->z); /* read first character */
733 lua_assert(c != LUA_SIGNATURE[0]); /* binary not supported */
734 checkmode(L, p->mode, "text");
735 cl = luaY_parser(L, p->z, &p->buff, &p->dyd, p->name, c);
736 lua_assert(cl->l.nupvalues == cl->l.p->sizeupvalues);
737 for (i = 0; i < cl->l.nupvalues; i++) { /* initialize upvalues */
738 UpVal *up = luaF_newupval(L);
739 cl->l.upvals[i] = up;
740 luaC_objbarrier(L, cl, up);
741 }
742 }
743
744
luaD_protectedparser(lua_State * L,ZIO * z,const char * name,const char * mode)745 int luaD_protectedparser (lua_State *L, ZIO *z, const char *name,
746 const char *mode) {
747 struct SParser p;
748 int status;
749 L->nny++; /* cannot yield during parsing */
750 p.z = z; p.name = name; p.mode = mode;
751 p.dyd.actvar.arr = NULL; p.dyd.actvar.size = 0;
752 p.dyd.gt.arr = NULL; p.dyd.gt.size = 0;
753 p.dyd.label.arr = NULL; p.dyd.label.size = 0;
754 luaZ_initbuffer(L, &p.buff);
755 status = luaD_pcall(L, f_parser, &p, savestack(L, L->top), L->errfunc);
756 luaZ_freebuffer(L, &p.buff);
757 luaM_freearray(L, p.dyd.actvar.arr, p.dyd.actvar.size);
758 luaM_freearray(L, p.dyd.gt.arr, p.dyd.gt.size);
759 luaM_freearray(L, p.dyd.label.arr, p.dyd.label.size);
760 L->nny--;
761 return status;
762 }
763