1 // SPDX-License-Identifier: MIT
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 #include <sys/asm_linkage.h>
14
15 #include "lapi.h"
16 #include "ldebug.h"
17 #include "ldo.h"
18 #include "lfunc.h"
19 #include "lgc.h"
20 #include "lmem.h"
21 #include "lobject.h"
22 #include "lopcodes.h"
23 #include "lparser.h"
24 #include "lstate.h"
25 #include "lstring.h"
26 #include "ltable.h"
27 #include "ltm.h"
28 #include "lvm.h"
29 #include "lzio.h"
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 #elif defined(__loongarch_lp64)
89 #define JMP_BUF_CNT 64
90 #else
91 #define JMP_BUF_CNT 1
92 #endif
93
94 typedef struct _label_t { long long unsigned val[JMP_BUF_CNT]; } label_t;
95
96 int ASMABI setjmp(label_t *) __attribute__ ((__nothrow__));
97 extern __attribute__((noreturn)) void ASMABI longjmp(label_t *);
98
99 #define LUAI_THROW(L,c) longjmp(&(c)->b)
100 #define LUAI_TRY(L,c,a) if (setjmp(&(c)->b) == 0) { a }
101 #define luai_jmpbuf label_t
102
103 /* unsupported arches will build but not be able to run lua programs */
104 #if JMP_BUF_CNT == 1
setjmp(label_t * buf)105 int setjmp (label_t *buf) {
106 return 1;
107 }
108
longjmp(label_t * buf)109 void longjmp (label_t * buf) {
110 for (;;);
111 }
112 #endif
113 #else
114 #define LUAI_THROW(L,c) longjmp((c)->b, 1)
115 #define LUAI_TRY(L,c,a) if (setjmp((c)->b) == 0) { a }
116 #define luai_jmpbuf jmp_buf
117 #endif
118
119 #else /* _KERNEL */
120
121 #if defined(__cplusplus) && !defined(LUA_USE_LONGJMP)
122 /* C++ exceptions */
123 #define LUAI_THROW(L,c) throw(c)
124 #define LUAI_TRY(L,c,a) \
125 try { a } catch(...) { if ((c)->status == 0) (c)->status = -1; }
126 #define luai_jmpbuf int /* dummy variable */
127
128 #elif defined(LUA_USE_ULONGJMP)
129 /* in Unix, try _longjmp/_setjmp (more efficient) */
130 #define LUAI_THROW(L,c) _longjmp((c)->b, 1)
131 #define LUAI_TRY(L,c,a) if (_setjmp((c)->b) == 0) { a }
132 #define luai_jmpbuf jmp_buf
133
134 #else
135 /* default handling with long jumps */
136 #define LUAI_THROW(L,c) longjmp((c)->b, 1)
137 #define LUAI_TRY(L,c,a) if (setjmp((c)->b) == 0) { a }
138 #define luai_jmpbuf jmp_buf
139
140 #endif
141
142 #endif /* _KERNEL */
143
144 #endif /* LUAI_THROW */
145
146
147 /* chain list of long jump buffers */
148 struct lua_longjmp {
149 struct lua_longjmp *previous;
150 luai_jmpbuf b;
151 volatile int status; /* error code */
152 };
153
154
seterrorobj(lua_State * L,int errcode,StkId oldtop)155 static void seterrorobj (lua_State *L, int errcode, StkId oldtop) {
156 switch (errcode) {
157 case LUA_ERRMEM: { /* memory error? */
158 setsvalue2s(L, oldtop, G(L)->memerrmsg); /* reuse preregistered msg. */
159 break;
160 }
161 case LUA_ERRERR: {
162 setsvalue2s(L, oldtop, luaS_newliteral(L, "error in error handling"));
163 break;
164 }
165 default: {
166 setobjs2s(L, oldtop, L->top - 1); /* error message on current top */
167 break;
168 }
169 }
170 L->top = oldtop + 1;
171 }
172
173 /*
174 * Silence infinite recursion warning which was added to -Wall in gcc 12.1
175 */
176 #if defined(__GNUC__) && !defined(__clang__) && \
177 defined(HAVE_KERNEL_INFINITE_RECURSION)
178 #pragma GCC diagnostic push
179 #pragma GCC diagnostic ignored "-Winfinite-recursion"
180 #endif
181
luaD_throw(lua_State * L,int errcode)182 l_noret luaD_throw (lua_State *L, int errcode) {
183 if (L->errorJmp) { /* thread has an error handler? */
184 L->errorJmp->status = errcode; /* set status */
185 LUAI_THROW(L, L->errorJmp); /* jump to it */
186 }
187 else { /* thread has no error handler */
188 L->status = cast_byte(errcode); /* mark it as dead */
189 if (G(L)->mainthread->errorJmp) { /* main thread has a handler? */
190 setobjs2s(L, G(L)->mainthread->top++, L->top - 1); /* copy error obj. */
191 luaD_throw(G(L)->mainthread, errcode); /* re-throw in main thread */
192 }
193 else { /* no handler at all; abort */
194 if (G(L)->panic) { /* panic function? */
195 lua_unlock(L);
196 G(L)->panic(L); /* call it (last chance to jump out) */
197 }
198 panic("no error handler");
199 }
200 }
201 }
202
203 #if defined(__GNUC__) && !defined(__clang__) && \
204 defined(HAVE_INFINITE_RECURSION)
205 #pragma GCC diagnostic pop
206 #endif
207
208
luaD_rawrunprotected(lua_State * L,Pfunc f,void * ud)209 int luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud) {
210 unsigned short oldnCcalls = L->nCcalls;
211 struct lua_longjmp lj;
212 lj.status = LUA_OK;
213 lj.previous = L->errorJmp; /* chain new error handler */
214 L->errorJmp = &lj;
215 LUAI_TRY(L, &lj,
216 (*f)(L, ud);
217 );
218 L->errorJmp = lj.previous; /* restore old error handler */
219 L->nCcalls = oldnCcalls;
220 return lj.status;
221 }
222
223 /* }====================================================== */
224
225
correctstack(lua_State * L,TValue * oldstack)226 static void correctstack (lua_State *L, TValue *oldstack) {
227 CallInfo *ci;
228 GCObject *up;
229 L->top = (L->top - oldstack) + L->stack;
230 for (up = L->openupval; up != NULL; up = up->gch.next)
231 gco2uv(up)->v = (gco2uv(up)->v - oldstack) + L->stack;
232 for (ci = L->ci; ci != NULL; ci = ci->previous) {
233 ci->top = (ci->top - oldstack) + L->stack;
234 ci->func = (ci->func - oldstack) + L->stack;
235 if (isLua(ci))
236 ci->u.l.base = (ci->u.l.base - oldstack) + L->stack;
237 }
238 }
239
240
241 /* some space for error handling */
242 #define ERRORSTACKSIZE (LUAI_MAXSTACK + 200)
243
244
luaD_reallocstack(lua_State * L,int newsize)245 void luaD_reallocstack (lua_State *L, int newsize) {
246 TValue *oldstack = L->stack;
247 int lim = L->stacksize;
248 lua_assert(newsize <= LUAI_MAXSTACK || newsize == ERRORSTACKSIZE);
249 lua_assert(L->stack_last - L->stack == L->stacksize - EXTRA_STACK);
250 luaM_reallocvector(L, L->stack, L->stacksize, newsize, TValue);
251 for (; lim < newsize; lim++)
252 setnilvalue(L->stack + lim); /* erase new segment */
253 L->stacksize = newsize;
254 L->stack_last = L->stack + newsize - EXTRA_STACK;
255 correctstack(L, oldstack);
256 }
257
258
luaD_growstack(lua_State * L,int n)259 void luaD_growstack (lua_State *L, int n) {
260 int size = L->stacksize;
261 if (size > LUAI_MAXSTACK) /* error after extra size? */
262 luaD_throw(L, LUA_ERRERR);
263 else {
264 int needed = cast_int(L->top - L->stack) + n + EXTRA_STACK;
265 int newsize = 2 * size;
266 if (newsize > LUAI_MAXSTACK) newsize = LUAI_MAXSTACK;
267 if (newsize < needed) newsize = needed;
268 if (newsize > LUAI_MAXSTACK) { /* stack overflow? */
269 luaD_reallocstack(L, ERRORSTACKSIZE);
270 luaG_runerror(L, "stack overflow");
271 }
272 else
273 luaD_reallocstack(L, newsize);
274 }
275 }
276
277
stackinuse(lua_State * L)278 static int stackinuse (lua_State *L) {
279 CallInfo *ci;
280 StkId lim = L->top;
281 for (ci = L->ci; ci != NULL; ci = ci->previous) {
282 lua_assert(ci->top <= L->stack_last);
283 if (lim < ci->top) lim = ci->top;
284 }
285 return cast_int(lim - L->stack) + 1; /* part of stack in use */
286 }
287
288
luaD_shrinkstack(lua_State * L)289 void luaD_shrinkstack (lua_State *L) {
290 int inuse = stackinuse(L);
291 int goodsize = inuse + (inuse / 8) + 2*EXTRA_STACK;
292 if (goodsize > LUAI_MAXSTACK) goodsize = LUAI_MAXSTACK;
293 if (inuse > LUAI_MAXSTACK || /* handling stack overflow? */
294 goodsize >= L->stacksize) /* would grow instead of shrink? */
295 condmovestack(L); /* don't change stack (change only for debugging) */
296 else
297 luaD_reallocstack(L, goodsize); /* shrink it */
298 }
299
300
luaD_hook(lua_State * L,int event,int line)301 void luaD_hook (lua_State *L, int event, int line) {
302 lua_Hook hook = L->hook;
303 if (hook && L->allowhook) {
304 CallInfo *ci = L->ci;
305 ptrdiff_t top = savestack(L, L->top);
306 ptrdiff_t ci_top = savestack(L, ci->top);
307 lua_Debug ar;
308 ar.event = event;
309 ar.currentline = line;
310 ar.i_ci = ci;
311 luaD_checkstack(L, LUA_MINSTACK); /* ensure minimum stack size */
312 ci->top = L->top + LUA_MINSTACK;
313 lua_assert(ci->top <= L->stack_last);
314 L->allowhook = 0; /* cannot call hooks inside a hook */
315 ci->callstatus |= CIST_HOOKED;
316 lua_unlock(L);
317 (*hook)(L, &ar);
318 lua_lock(L);
319 lua_assert(!L->allowhook);
320 L->allowhook = 1;
321 ci->top = restorestack(L, ci_top);
322 L->top = restorestack(L, top);
323 ci->callstatus &= ~CIST_HOOKED;
324 }
325 }
326
327
callhook(lua_State * L,CallInfo * ci)328 static void callhook (lua_State *L, CallInfo *ci) {
329 int hook = LUA_HOOKCALL;
330 ci->u.l.savedpc++; /* hooks assume 'pc' is already incremented */
331 if (isLua(ci->previous) &&
332 GET_OPCODE(*(ci->previous->u.l.savedpc - 1)) == OP_TAILCALL) {
333 ci->callstatus |= CIST_TAIL;
334 hook = LUA_HOOKTAILCALL;
335 }
336 luaD_hook(L, hook, -1);
337 ci->u.l.savedpc--; /* correct 'pc' */
338 }
339
340
adjust_varargs(lua_State * L,Proto * p,int actual)341 static StkId adjust_varargs (lua_State *L, Proto *p, int actual) {
342 int i;
343 int nfixargs = p->numparams;
344 StkId base, fixed;
345 lua_assert(actual >= nfixargs);
346 /* move fixed parameters to final position */
347 luaD_checkstack(L, p->maxstacksize); /* check again for new 'base' */
348 fixed = L->top - actual; /* first fixed argument */
349 base = L->top; /* final position of first argument */
350 for (i=0; i<nfixargs; i++) {
351 setobjs2s(L, L->top++, fixed + i);
352 setnilvalue(fixed + i);
353 }
354 return base;
355 }
356
357
tryfuncTM(lua_State * L,StkId func)358 static StkId tryfuncTM (lua_State *L, StkId func) {
359 const TValue *tm = luaT_gettmbyobj(L, func, TM_CALL);
360 StkId p;
361 ptrdiff_t funcr = savestack(L, func);
362 if (!ttisfunction(tm))
363 luaG_typeerror(L, func, "call");
364 /* Open a hole inside the stack at `func' */
365 for (p = L->top; p > func; p--) setobjs2s(L, p, p-1);
366 incr_top(L);
367 func = restorestack(L, funcr); /* previous call may change stack */
368 setobj2s(L, func, tm); /* tag method is the new function to be called */
369 return func;
370 }
371
372
373
374 #define next_ci(L) (L->ci = (L->ci->next ? L->ci->next : luaE_extendCI(L)))
375
376
377 /*
378 ** returns true if function has been executed (C function)
379 */
luaD_precall(lua_State * L,StkId func,int nresults)380 int luaD_precall (lua_State *L, StkId func, int nresults) {
381 lua_CFunction f;
382 CallInfo *ci;
383 int n; /* number of arguments (Lua) or returns (C) */
384 ptrdiff_t funcr = savestack(L, func);
385 switch (ttype(func)) {
386 case LUA_TLCF: /* light C function */
387 f = fvalue(func);
388 goto Cfunc;
389 case LUA_TCCL: { /* C closure */
390 f = clCvalue(func)->f;
391 Cfunc:
392 luaD_checkstack(L, LUA_MINSTACK); /* ensure minimum stack size */
393 ci = next_ci(L); /* now 'enter' new function */
394 ci->nresults = nresults;
395 ci->func = restorestack(L, funcr);
396 ci->top = L->top + LUA_MINSTACK;
397 lua_assert(ci->top <= L->stack_last);
398 ci->callstatus = 0;
399 luaC_checkGC(L); /* stack grow uses memory */
400 if (L->hookmask & LUA_MASKCALL)
401 luaD_hook(L, LUA_HOOKCALL, -1);
402 lua_unlock(L);
403 n = (*f)(L); /* do the actual call */
404 lua_lock(L);
405 api_checknelems(L, n);
406 luaD_poscall(L, L->top - n);
407 return 1;
408 }
409 case LUA_TLCL: { /* Lua function: prepare its call */
410 StkId base;
411 Proto *p = clLvalue(func)->p;
412 n = cast_int(L->top - func) - 1; /* number of real arguments */
413 luaD_checkstack(L, p->maxstacksize + p->numparams);
414 for (; n < p->numparams; n++)
415 setnilvalue(L->top++); /* complete missing arguments */
416 if (!p->is_vararg) {
417 func = restorestack(L, funcr);
418 base = func + 1;
419 }
420 else {
421 base = adjust_varargs(L, p, n);
422 func = restorestack(L, funcr); /* previous call can change stack */
423 }
424 ci = next_ci(L); /* now 'enter' new function */
425 ci->nresults = nresults;
426 ci->func = func;
427 ci->u.l.base = base;
428 ci->top = base + p->maxstacksize;
429 lua_assert(ci->top <= L->stack_last);
430 ci->u.l.savedpc = p->code; /* starting point */
431 ci->callstatus = CIST_LUA;
432 L->top = ci->top;
433 luaC_checkGC(L); /* stack grow uses memory */
434 if (L->hookmask & LUA_MASKCALL)
435 callhook(L, ci);
436 return 0;
437 }
438 default: { /* not a function */
439 func = tryfuncTM(L, func); /* retry with 'function' tag method */
440 return luaD_precall(L, func, nresults); /* now it must be a function */
441 }
442 }
443 }
444
445
luaD_poscall(lua_State * L,StkId firstResult)446 int luaD_poscall (lua_State *L, StkId firstResult) {
447 StkId res;
448 int wanted, i;
449 CallInfo *ci = L->ci;
450 if (L->hookmask & (LUA_MASKRET | LUA_MASKLINE)) {
451 if (L->hookmask & LUA_MASKRET) {
452 ptrdiff_t fr = savestack(L, firstResult); /* hook may change stack */
453 luaD_hook(L, LUA_HOOKRET, -1);
454 firstResult = restorestack(L, fr);
455 }
456 L->oldpc = ci->previous->u.l.savedpc; /* 'oldpc' for caller function */
457 }
458 res = ci->func; /* res == final position of 1st result */
459 wanted = ci->nresults;
460 L->ci = ci->previous; /* back to caller */
461 /* move results to correct place */
462 for (i = wanted; i != 0 && firstResult < L->top; i--)
463 setobjs2s(L, res++, firstResult++);
464 while (i-- > 0)
465 setnilvalue(res++);
466 L->top = res;
467 return (wanted - LUA_MULTRET); /* 0 iff wanted == LUA_MULTRET */
468 }
469
470
471 /*
472 ** Call a function (C or Lua). The function to be called is at *func.
473 ** The arguments are on the stack, right after the function.
474 ** When returns, all the results are on the stack, starting at the original
475 ** function position.
476 */
luaD_call(lua_State * L,StkId func,int nResults,int allowyield)477 void luaD_call (lua_State *L, StkId func, int nResults, int allowyield) {
478 if (++L->nCcalls >= LUAI_MAXCCALLS) {
479 if (L->nCcalls == LUAI_MAXCCALLS)
480 luaG_runerror(L, "C stack overflow");
481 else if (L->nCcalls >= (LUAI_MAXCCALLS + (LUAI_MAXCCALLS>>3)))
482 luaD_throw(L, LUA_ERRERR); /* error while handling stack error */
483 }
484 intptr_t remaining = stack_remaining();
485 if (L->runerror == 0 && remaining < LUAI_MINCSTACK)
486 luaG_runerror(L, "C stack overflow");
487 if (L->runerror != 0 && remaining < LUAI_MINCSTACK / 2)
488 luaD_throw(L, LUA_ERRERR); /* error while handling stack error */
489 if (!allowyield) L->nny++;
490 if (!luaD_precall(L, func, nResults)) /* is a Lua function? */
491 luaV_execute(L); /* call it */
492 if (!allowyield) L->nny--;
493 L->nCcalls--;
494 }
495
496
finishCcall(lua_State * L)497 static void finishCcall (lua_State *L) {
498 CallInfo *ci = L->ci;
499 int n;
500 lua_assert(ci->u.c.k != NULL); /* must have a continuation */
501 lua_assert(L->nny == 0);
502 if (ci->callstatus & CIST_YPCALL) { /* was inside a pcall? */
503 ci->callstatus &= ~CIST_YPCALL; /* finish 'lua_pcall' */
504 L->errfunc = ci->u.c.old_errfunc;
505 }
506 /* finish 'lua_callk'/'lua_pcall' */
507 adjustresults(L, ci->nresults);
508 /* call continuation function */
509 if (!(ci->callstatus & CIST_STAT)) /* no call status? */
510 ci->u.c.status = LUA_YIELD; /* 'default' status */
511 lua_assert(ci->u.c.status != LUA_OK);
512 ci->callstatus = (ci->callstatus & ~(CIST_YPCALL | CIST_STAT)) | CIST_YIELDED;
513 lua_unlock(L);
514 n = (*ci->u.c.k)(L);
515 lua_lock(L);
516 api_checknelems(L, n);
517 /* finish 'luaD_precall' */
518 luaD_poscall(L, L->top - n);
519 }
520
521
unroll(lua_State * L,void * ud)522 static void unroll (lua_State *L, void *ud) {
523 UNUSED(ud);
524 for (;;) {
525 if (L->ci == &L->base_ci) /* stack is empty? */
526 return; /* coroutine finished normally */
527 if (!isLua(L->ci)) /* C function? */
528 finishCcall(L);
529 else { /* Lua function */
530 luaV_finishOp(L); /* finish interrupted instruction */
531 luaV_execute(L); /* execute down to higher C 'boundary' */
532 }
533 }
534 }
535
536
537 /*
538 ** check whether thread has a suspended protected call
539 */
findpcall(lua_State * L)540 static CallInfo *findpcall (lua_State *L) {
541 CallInfo *ci;
542 for (ci = L->ci; ci != NULL; ci = ci->previous) { /* search for a pcall */
543 if (ci->callstatus & CIST_YPCALL)
544 return ci;
545 }
546 return NULL; /* no pending pcall */
547 }
548
549
recover(lua_State * L,int status)550 static int recover (lua_State *L, int status) {
551 StkId oldtop;
552 CallInfo *ci = findpcall(L);
553 if (ci == NULL) return 0; /* no recovery point */
554 /* "finish" luaD_pcall */
555 oldtop = restorestack(L, ci->extra);
556 luaF_close(L, oldtop);
557 seterrorobj(L, status, oldtop);
558 L->ci = ci;
559 L->allowhook = ci->u.c.old_allowhook;
560 L->nny = 0; /* should be zero to be yieldable */
561 luaD_shrinkstack(L);
562 L->errfunc = ci->u.c.old_errfunc;
563 ci->callstatus |= CIST_STAT; /* call has error status */
564 ci->u.c.status = status; /* (here it is) */
565 return 1; /* continue running the coroutine */
566 }
567
568
569 /*
570 ** signal an error in the call to 'resume', not in the execution of the
571 ** coroutine itself. (Such errors should not be handled by any coroutine
572 ** error handler and should not kill the coroutine.)
573 */
resume_error(lua_State * L,const char * msg,StkId firstArg)574 static l_noret resume_error (lua_State *L, const char *msg, StkId firstArg) {
575 L->top = firstArg; /* remove args from the stack */
576 setsvalue2s(L, L->top, luaS_new(L, msg)); /* push error message */
577 api_incr_top(L);
578 luaD_throw(L, -1); /* jump back to 'lua_resume' */
579 }
580
581
582 /*
583 ** do the work for 'lua_resume' in protected mode
584 */
resume_cb(lua_State * L,void * ud)585 static void resume_cb (lua_State *L, void *ud) {
586 int nCcalls = L->nCcalls;
587 StkId firstArg = cast(StkId, ud);
588 CallInfo *ci = L->ci;
589 if (nCcalls >= LUAI_MAXCCALLS)
590 resume_error(L, "C stack overflow", firstArg);
591 if (L->status == LUA_OK) { /* may be starting a coroutine */
592 if (ci != &L->base_ci) /* not in base level? */
593 resume_error(L, "cannot resume non-suspended coroutine", firstArg);
594 /* coroutine is in base level; start running it */
595 if (!luaD_precall(L, firstArg - 1, LUA_MULTRET)) /* Lua function? */
596 luaV_execute(L); /* call it */
597 }
598 else if (L->status != LUA_YIELD)
599 resume_error(L, "cannot resume dead coroutine", firstArg);
600 else { /* resuming from previous yield */
601 L->status = LUA_OK;
602 ci->func = restorestack(L, ci->extra);
603 if (isLua(ci)) /* yielded inside a hook? */
604 luaV_execute(L); /* just continue running Lua code */
605 else { /* 'common' yield */
606 if (ci->u.c.k != NULL) { /* does it have a continuation? */
607 int n;
608 ci->u.c.status = LUA_YIELD; /* 'default' status */
609 ci->callstatus |= CIST_YIELDED;
610 lua_unlock(L);
611 n = (*ci->u.c.k)(L); /* call continuation */
612 lua_lock(L);
613 api_checknelems(L, n);
614 firstArg = L->top - n; /* yield results come from continuation */
615 }
616 luaD_poscall(L, firstArg); /* finish 'luaD_precall' */
617 }
618 unroll(L, NULL);
619 }
620 lua_assert(nCcalls == L->nCcalls);
621 }
622
623
lua_resume(lua_State * L,lua_State * from,int nargs)624 LUA_API int lua_resume (lua_State *L, lua_State *from, int nargs) {
625 int status;
626 int oldnny = L->nny; /* save 'nny' */
627 lua_lock(L);
628 luai_userstateresume(L, nargs);
629 L->nCcalls = (from) ? from->nCcalls + 1 : 1;
630 L->nny = 0; /* allow yields */
631 api_checknelems(L, (L->status == LUA_OK) ? nargs + 1 : nargs);
632 status = luaD_rawrunprotected(L, resume_cb, L->top - nargs);
633 if (status == -1) /* error calling 'lua_resume'? */
634 status = LUA_ERRRUN;
635 else { /* yield or regular error */
636 while (status != LUA_OK && status != LUA_YIELD) { /* error? */
637 if (recover(L, status)) /* recover point? */
638 status = luaD_rawrunprotected(L, unroll, NULL); /* run continuation */
639 else { /* unrecoverable error */
640 L->status = cast_byte(status); /* mark thread as `dead' */
641 seterrorobj(L, status, L->top);
642 L->ci->top = L->top;
643 break;
644 }
645 }
646 lua_assert(status == L->status);
647 }
648 L->nny = oldnny; /* restore 'nny' */
649 L->nCcalls--;
650 lua_assert(L->nCcalls == ((from) ? from->nCcalls : 0));
651 lua_unlock(L);
652 return status;
653 }
654
655
lua_yieldk(lua_State * L,int nresults,int ctx,lua_CFunction k)656 LUA_API int lua_yieldk (lua_State *L, int nresults, int ctx, lua_CFunction k) {
657 CallInfo *ci = L->ci;
658 luai_userstateyield(L, nresults);
659 lua_lock(L);
660 api_checknelems(L, nresults);
661 if (L->nny > 0) {
662 if (L != G(L)->mainthread)
663 luaG_runerror(L, "attempt to yield across a C-call boundary");
664 else
665 luaG_runerror(L, "attempt to yield from outside a coroutine");
666 }
667 L->status = LUA_YIELD;
668 ci->extra = savestack(L, ci->func); /* save current 'func' */
669 if (isLua(ci)) { /* inside a hook? */
670 api_check(L, k == NULL, "hooks cannot continue after yielding");
671 }
672 else {
673 if ((ci->u.c.k = k) != NULL) /* is there a continuation? */
674 ci->u.c.ctx = ctx; /* save context */
675 ci->func = L->top - nresults - 1; /* protect stack below results */
676 luaD_throw(L, LUA_YIELD);
677 }
678 lua_assert(ci->callstatus & CIST_HOOKED); /* must be inside a hook */
679 lua_unlock(L);
680 return 0; /* return to 'luaD_hook' */
681 }
682
683
luaD_pcall(lua_State * L,Pfunc func,void * u,ptrdiff_t old_top,ptrdiff_t ef)684 int luaD_pcall (lua_State *L, Pfunc func, void *u,
685 ptrdiff_t old_top, ptrdiff_t ef) {
686 int status;
687 CallInfo *old_ci = L->ci;
688 lu_byte old_allowhooks = L->allowhook;
689 unsigned short old_nny = L->nny;
690 ptrdiff_t old_errfunc = L->errfunc;
691 L->errfunc = ef;
692 status = luaD_rawrunprotected(L, func, u);
693 if (status != LUA_OK) { /* an error occurred? */
694 StkId oldtop = restorestack(L, old_top);
695 luaF_close(L, oldtop); /* close possible pending closures */
696 seterrorobj(L, status, oldtop);
697 L->ci = old_ci;
698 L->allowhook = old_allowhooks;
699 L->nny = old_nny;
700 luaD_shrinkstack(L);
701 }
702 L->errfunc = old_errfunc;
703 return status;
704 }
705
706
707
708 /*
709 ** Execute a protected parser.
710 */
711 struct SParser { /* data to `f_parser' */
712 ZIO *z;
713 Mbuffer buff; /* dynamic structure used by the scanner */
714 Dyndata dyd; /* dynamic structures used by the parser */
715 const char *mode;
716 const char *name;
717 };
718
719
checkmode(lua_State * L,const char * mode,const char * x)720 static void checkmode (lua_State *L, const char *mode, const char *x) {
721 if (mode && strchr(mode, x[0]) == NULL) {
722 luaO_pushfstring(L,
723 "attempt to load a %s chunk (mode is " LUA_QS ")", x, mode);
724 luaD_throw(L, LUA_ERRSYNTAX);
725 }
726 }
727
728
f_parser(lua_State * L,void * ud)729 static void f_parser (lua_State *L, void *ud) {
730 int i;
731 Closure *cl;
732 struct SParser *p = cast(struct SParser *, ud);
733 int c = zgetc(p->z); /* read first character */
734 lua_assert(c != LUA_SIGNATURE[0]); /* binary not supported */
735 checkmode(L, p->mode, "text");
736 cl = luaY_parser(L, p->z, &p->buff, &p->dyd, p->name, c);
737 lua_assert(cl->l.nupvalues == cl->l.p->sizeupvalues);
738 for (i = 0; i < cl->l.nupvalues; i++) { /* initialize upvalues */
739 UpVal *up = luaF_newupval(L);
740 cl->l.upvals[i] = up;
741 luaC_objbarrier(L, cl, up);
742 }
743 }
744
745
luaD_protectedparser(lua_State * L,ZIO * z,const char * name,const char * mode)746 int luaD_protectedparser (lua_State *L, ZIO *z, const char *name,
747 const char *mode) {
748 struct SParser p;
749 int status;
750 L->nny++; /* cannot yield during parsing */
751 p.z = z; p.name = name; p.mode = mode;
752 p.dyd.actvar.arr = NULL; p.dyd.actvar.size = 0;
753 p.dyd.gt.arr = NULL; p.dyd.gt.size = 0;
754 p.dyd.label.arr = NULL; p.dyd.label.size = 0;
755 luaZ_initbuffer(L, &p.buff);
756 status = luaD_pcall(L, f_parser, &p, savestack(L, L->top), L->errfunc);
757 luaZ_freebuffer(L, &p.buff);
758 luaM_freearray(L, p.dyd.actvar.arr, p.dyd.actvar.size);
759 luaM_freearray(L, p.dyd.gt.arr, p.dyd.gt.size);
760 luaM_freearray(L, p.dyd.label.arr, p.dyd.label.size);
761 L->nny--;
762 return status;
763 }
764