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 #include <setjmp.h>
9 #include <stdlib.h>
10 #include <string.h>
11 
12 #define ldo_c
13 #define LUA_CORE
14 
15 #include "lua.h"
16 
17 #include "lapi.h"
18 #include "ldebug.h"
19 #include "ldo.h"
20 #include "lfunc.h"
21 #include "lgc.h"
22 #include "lmem.h"
23 #include "lobject.h"
24 #include "lopcodes.h"
25 #include "lparser.h"
26 #include "lstate.h"
27 #include "lstring.h"
28 #include "ltable.h"
29 #include "ltm.h"
30 #include "lundump.h"
31 #include "lvm.h"
32 #include "lzio.h"
33 
34 
35 
36 
37 /*
38 ** {======================================================
39 ** Error-recovery functions
40 ** =======================================================
41 */
42 
43 /*
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.
48 */
49 #if !defined(LUAI_THROW)
50 
51 #if defined(__cplusplus) && !defined(LUA_USE_LONGJMP)
52 /* C++ exceptions */
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 */
57 
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
63 
64 #else
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
69 
70 #endif
71 
72 #endif
73 
74 
75 
76 /* chain list of long jump buffers */
77 struct lua_longjmp {
78   struct lua_longjmp *previous;
79   luai_jmpbuf b;
80   volatile int status;  /* error code */
81 };
82 
83 
seterrorobj(lua_State * L,int errcode,StkId oldtop)84 static void seterrorobj (lua_State *L, int errcode, StkId oldtop) {
85   switch (errcode) {
86     case LUA_ERRMEM: {  /* memory error? */
87       setsvalue2s(L, oldtop, G(L)->memerrmsg); /* reuse preregistered msg. */
88       break;
89     }
90     case LUA_ERRERR: {
91       setsvalue2s(L, oldtop, luaS_newliteral(L, "error in error handling"));
92       break;
93     }
94     default: {
95       setobjs2s(L, oldtop, L->top - 1);  /* error message on current top */
96       break;
97     }
98   }
99   L->top = oldtop + 1;
100 }
101 
102 
luaD_throw(lua_State * L,int errcode)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 */
107   }
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 */
113     }
114     else {  /* no handler at all; abort */
115       if (G(L)->panic) {  /* panic function? */
116         lua_unlock(L);
117         G(L)->panic(L);  /* call it (last chance to jump out) */
118       }
119       abort();
120     }
121   }
122 }
123 
124 
luaD_rawrunprotected(lua_State * L,Pfunc f,void * ud)125 int luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud) {
126   unsigned short oldnCcalls = L->nCcalls;
127   struct lua_longjmp lj;
128   lj.status = LUA_OK;
129   lj.previous = L->errorJmp;  /* chain new error handler */
130   L->errorJmp = &lj;
131   LUAI_TRY(L, &lj,
132     (*f)(L, ud);
133   );
134   L->errorJmp = lj.previous;  /* restore old error handler */
135   L->nCcalls = oldnCcalls;
136   return lj.status;
137 }
138 
139 /* }====================================================== */
140 
141 
correctstack(lua_State * L,TValue * oldstack)142 static void correctstack (lua_State *L, TValue *oldstack) {
143   CallInfo *ci;
144   GCObject *up;
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;
151     if (isLua(ci))
152       ci->u.l.base = (ci->u.l.base - oldstack) + L->stack;
153   }
154 }
155 
156 
157 /* some space for error handling */
158 #define ERRORSTACKSIZE  (LUAI_MAXSTACK + 200)
159 
160 
luaD_reallocstack(lua_State * L,int newsize)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);
172 }
173 
174 
luaD_growstack(lua_State * L,int n)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);
179   else {
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");
187     }
188     else
189       luaD_reallocstack(L, newsize);
190   }
191 }
192 
193 
stackinuse(lua_State * L)194 static int stackinuse (lua_State *L) {
195   CallInfo *ci;
196   StkId lim = L->top;
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;
200   }
201   return cast_int(lim - L->stack) + 1;  /* part of stack in use */
202 }
203 
204 
luaD_shrinkstack(lua_State * L)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) */
212   else
213     luaD_reallocstack(L, goodsize);  /* shrink it */
214 }
215 
216 
luaD_hook(lua_State * L,int event,int line)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);
223     lua_Debug ar;
224     ar.event = event;
225     ar.currentline = line;
226     ar.i_ci = ci;
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;
232     lua_unlock(L);
233     (*hook)(L, &ar);
234     lua_lock(L);
235     lua_assert(!L->allowhook);
236     L->allowhook = 1;
237     ci->top = restorestack(L, ci_top);
238     L->top = restorestack(L, top);
239     ci->callstatus &= ~CIST_HOOKED;
240   }
241 }
242 
243 
callhook(lua_State * L,CallInfo * ci)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;
251   }
252   luaD_hook(L, hook, -1);
253   ci->u.l.savedpc--;  /* correct 'pc' */
254 }
255 
256 
adjust_varargs(lua_State * L,Proto * p,int actual)257 static StkId adjust_varargs (lua_State *L, Proto *p, int actual) {
258   int i;
259   int nfixargs = p->numparams;
260   StkId base, fixed;
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);
269   }
270   return base;
271 }
272 
273 
tryfuncTM(lua_State * L,StkId func)274 static StkId tryfuncTM (lua_State *L, StkId func) {
275   const TValue *tm = luaT_gettmbyobj(L, func, TM_CALL);
276   StkId p;
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);
282   incr_top(L);
283   func = restorestack(L, funcr);  /* previous call may change stack */
284   setobj2s(L, func, tm);  /* tag method is the new function to be called */
285   return func;
286 }
287 
288 
289 
290 #define next_ci(L) (L->ci = (L->ci->next ? L->ci->next : luaE_extendCI(L)))
291 
292 
293 /*
294 ** returns true if function has been executed (C function)
295 */
luaD_precall(lua_State * L,StkId func,int nresults)296 int luaD_precall (lua_State *L, StkId func, int nresults) {
297   lua_CFunction f;
298   CallInfo *ci;
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 */
303       f = fvalue(func);
304       goto Cfunc;
305     case LUA_TCCL: {  /* C closure */
306       f = clCvalue(func)->f;
307      Cfunc:
308       luaD_checkstack(L, LUA_MINSTACK);  /* ensure minimum stack size */
309       ci = next_ci(L);  /* now 'enter' new function */
310       ci->nresults = (short)nresults;
311       ci->func = restorestack(L, funcr);
312       ci->top = L->top + LUA_MINSTACK;
313       lua_assert(ci->top <= L->stack_last);
314       ci->callstatus = 0;
315       luaC_checkGC(L);  /* stack grow uses memory */
316       if (L->hookmask & LUA_MASKCALL)
317         luaD_hook(L, LUA_HOOKCALL, -1);
318       lua_unlock(L);
319       n = (*f)(L);  /* do the actual call */
320       lua_lock(L);
321       api_checknelems(L, n);
322       luaD_poscall(L, L->top - n);
323       return 1;
324     }
325     case LUA_TLCL: {  /* Lua function: prepare its call */
326       StkId base;
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 */
332       if (!p->is_vararg) {
333         func = restorestack(L, funcr);
334         base = func + 1;
335       }
336       else {
337         base = adjust_varargs(L, p, n);
338         func = restorestack(L, funcr);  /* previous call can change stack */
339       }
340       ci = next_ci(L);  /* now 'enter' new function */
341       ci->nresults = (short)nresults;
342       ci->func = func;
343       ci->u.l.base = base;
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;
348       L->top = ci->top;
349       luaC_checkGC(L);  /* stack grow uses memory */
350       if (L->hookmask & LUA_MASKCALL)
351         callhook(L, ci);
352       return 0;
353     }
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 */
357     }
358   }
359 }
360 
361 
luaD_poscall(lua_State * L,StkId firstResult)362 int luaD_poscall (lua_State *L, StkId firstResult) {
363   StkId res;
364   int wanted, i;
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);
371     }
372     L->oldpc = ci->previous->u.l.savedpc;  /* 'oldpc' for caller function */
373   }
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++);
380   while (i-- > 0)
381     setnilvalue(res++);
382   L->top = res;
383   return (wanted - LUA_MULTRET);  /* 0 iff wanted == LUA_MULTRET */
384 }
385 
386 
387 /*
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.
392 */
luaD_call(lua_State * L,StkId func,int nResults,int allowyield)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 */
399   }
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--;
404   L->nCcalls--;
405 }
406 
407 
finishCcall(lua_State * L)408 static void finishCcall (lua_State *L) {
409   CallInfo *ci = L->ci;
410   int n;
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;
416   }
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;
424   lua_unlock(L);
425   n = (*ci->u.c.k)(L);
426   lua_lock(L);
427   api_checknelems(L, n);
428   /* finish 'luaD_precall' */
429   luaD_poscall(L, L->top - n);
430 }
431 
432 
unroll(lua_State * L,void * ud)433 static void unroll (lua_State *L, void *ud) {
434   UNUSED(ud);
435   for (;;) {
436     if (L->ci == &L->base_ci)  /* stack is empty? */
437       return;  /* coroutine finished normally */
438     if (!isLua(L->ci))  /* C function? */
439       finishCcall(L);
440     else {  /* Lua function */
441       luaV_finishOp(L);  /* finish interrupted instruction */
442       luaV_execute(L);  /* execute down to higher C 'boundary' */
443     }
444   }
445 }
446 
447 
448 /*
449 ** check whether thread has a suspended protected call
450 */
findpcall(lua_State * L)451 static CallInfo *findpcall (lua_State *L) {
452   CallInfo *ci;
453   for (ci = L->ci; ci != NULL; ci = ci->previous) {  /* search for a pcall */
454     if (ci->callstatus & CIST_YPCALL)
455       return ci;
456   }
457   return NULL;  /* no pending pcall */
458 }
459 
460 
recover(lua_State * L,int status)461 static int recover (lua_State *L, int status) {
462   StkId oldtop;
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);
469   L->ci = ci;
470   L->allowhook = ci->u.c.old_allowhook;
471   L->nny = 0;  /* should be zero to be yieldable */
472   luaD_shrinkstack(L);
473   L->errfunc = ci->u.c.old_errfunc;
474   ci->callstatus |= CIST_STAT;  /* call has error status */
475   ci->u.c.status = (lu_byte)status;  /* (here it is) */
476   return 1;  /* continue running the coroutine */
477 }
478 
479 
480 /*
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.)
484 */
resume_error(lua_State * L,const char * msg,StkId firstArg)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 */
488   api_incr_top(L);
489   luaD_throw(L, -1);  /* jump back to 'lua_resume' */
490 }
491 
492 
493 /*
494 ** do the work for 'lua_resume' in protected mode
495 */
resume(lua_State * L,void * ud)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 */
508   }
509   else if (L->status != LUA_YIELD)
510     resume_error(L, "cannot resume dead coroutine", firstArg);
511   else {  /* resuming from previous yield */
512     L->status = LUA_OK;
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? */
518         int n;
519         ci->u.c.status = LUA_YIELD;  /* 'default' status */
520         ci->callstatus |= CIST_YIELDED;
521         lua_unlock(L);
522         n = (*ci->u.c.k)(L);  /* call continuation */
523         lua_lock(L);
524         api_checknelems(L, n);
525         firstArg = L->top - n;  /* yield results come from continuation */
526       }
527       luaD_poscall(L, firstArg);  /* finish 'luaD_precall' */
528     }
529     unroll(L, NULL);
530   }
531   lua_assert(nCcalls == L->nCcalls);
532 }
533 
534 
lua_resume(lua_State * L,lua_State * from,int nargs)535 LUA_API int lua_resume (lua_State *L, lua_State *from, int nargs) {
536   int status;
537   int oldnny = L->nny;  /* save 'nny' */
538   lua_lock(L);
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'? */
545     status = LUA_ERRRUN;
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);
553         L->ci->top = L->top;
554         break;
555       }
556     }
557     lua_assert(status == L->status);
558   }
559   L->nny = (unsigned short)oldnny;  /* restore 'nny' */
560   L->nCcalls--;
561   lua_assert(L->nCcalls == ((from) ? from->nCcalls : 0));
562   lua_unlock(L);
563   return status;
564 }
565 
566 
lua_yieldk(lua_State * L,int nresults,int ctx,lua_CFunction k)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);
570   lua_lock(L);
571   api_checknelems(L, nresults);
572   if (L->nny > 0) {
573     if (L != G(L)->mainthread)
574       luaG_runerror(L, "attempt to yield across a C-call boundary");
575     else
576       luaG_runerror(L, "attempt to yield from outside a coroutine");
577   }
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");
582   }
583   else {
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);
588   }
589   lua_assert(ci->callstatus & CIST_HOOKED);  /* must be inside a hook */
590   lua_unlock(L);
591   return 0;  /* return to 'luaD_hook' */
592 }
593 
594 
luaD_pcall(lua_State * L,Pfunc func,void * u,ptrdiff_t old_top,ptrdiff_t ef)595 int luaD_pcall (lua_State *L, Pfunc func, void *u,
596                 ptrdiff_t old_top, ptrdiff_t ef) {
597   int status;
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;
602   L->errfunc = ef;
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);
608     L->ci = old_ci;
609     L->allowhook = old_allowhooks;
610     L->nny = old_nny;
611     luaD_shrinkstack(L);
612   }
613   L->errfunc = old_errfunc;
614   return status;
615 }
616 
617 
618 
619 /*
620 ** Execute a protected parser.
621 */
622 struct SParser {  /* data to `f_parser' */
623   ZIO *z;
624   Mbuffer buff;  /* dynamic structure used by the scanner */
625   Dyndata dyd;  /* dynamic structures used by the parser */
626   const char *mode;
627   const char *name;
628 };
629 
630 
checkmode(lua_State * L,const char * mode,const char * x)631 static void checkmode (lua_State *L, const char *mode, const char *x) {
632   if (mode && strchr(mode, x[0]) == NULL) {
633     luaO_pushfstring(L,
634        "attempt to load a %s chunk (mode is " LUA_QS ")", x, mode);
635     luaD_throw(L, LUA_ERRSYNTAX);
636   }
637 }
638 
639 
f_parser(lua_State * L,void * ud)640 static void f_parser (lua_State *L, void *ud) {
641   int i;
642   Closure *cl;
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);
648   }
649   else {
650     checkmode(L, p->mode, "text");
651     cl = luaY_parser(L, p->z, &p->buff, &p->dyd, p->name, c);
652   }
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);
658   }
659 }
660 
661 
luaD_protectedparser(lua_State * L,ZIO * z,const char * name,const char * mode)662 int luaD_protectedparser (lua_State *L, ZIO *z, const char *name,
663                                         const char *mode) {
664   struct SParser p;
665   int status;
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);
677   L->nny--;
678   return status;
679 }
680 
681 
682