client/deps/liblua/ldo.c

   1 /*
   2 ** $Id: ldo.c,v 2.108 2012/10/01 14:05:04 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
  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
 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     } else { /* thread has no error handler */
 108         L->status = cast_byte(errcode);  /* mark it as dead */
 109         if (G(L)->mainthread->errorJmp) {  /* main thread has a handler? */
 110             setobjs2s(L, G(L)->mainthread->top++, L->top - 1);  /* copy error obj. */
 111             luaD_throw(G(L)->mainthread, errcode);  /* re-throw in main thread */
 112         } else { /* no handler at all; abort */
 113             if (G(L)->panic) {  /* panic function? */
 114                 lua_unlock(L);
 115                 G(L)->panic(L);  /* call it (last chance to jump out) */
 116             }
 117             abort();
 118         }
 119     }
 120 }
 121
 122
 123 int luaD_rawrunprotected(lua_State *L, Pfunc f, void *ud) {
 124     unsigned short oldnCcalls = L->nCcalls;
 125     struct lua_longjmp lj;
 126     lj.status = LUA_OK;
 127     lj.previous = L->errorJmp;  /* chain new error handler */
 128     L->errorJmp = &lj;
 129     LUAI_TRY(L, &lj,
 130              (*f)(L, ud);
 131             );
 132     L->errorJmp = lj.previous;  /* restore old error handler */
 133     L->nCcalls = oldnCcalls;
 134     return lj.status;
 135 }
 136
 137 /* }====================================================== */
 138
 139
 140 static void correctstack(lua_State *L, TValue *oldstack) {
 141     CallInfo *ci;
 142     GCObject *up;
 143     L->top = (L->top - oldstack) + L->stack;
 144     for (up = L->openupval; up != NULL; up = up->gch.next)
 145         gco2uv(up)->v = (gco2uv(up)->v - oldstack) + L->stack;
 146     for (ci = L->ci; ci != NULL; ci = ci->previous) {
 147         ci->top = (ci->top - oldstack) + L->stack;
 148         ci->func = (ci->func - oldstack) + L->stack;
 149         if (isLua(ci))
 150             ci->u.l.base = (ci->u.l.base - oldstack) + L->stack;
 151     }
 152 }
 153
 154
 155 /* some space for error handling */
 156 #define ERRORSTACKSIZE (LUAI_MAXSTACK + 200)
 157
 158
 159 void luaD_reallocstack(lua_State *L, int newsize) {
 160     TValue *oldstack = L->stack;
 161     int lim = L->stacksize;
 162     lua_assert(newsize <= LUAI_MAXSTACK || newsize == ERRORSTACKSIZE);
 163     lua_assert(L->stack_last - L->stack == L->stacksize - EXTRA_STACK);
 164     luaM_reallocvector(L, L->stack, L->stacksize, newsize, TValue);
 165     for (; lim < newsize; lim++)
 166         setnilvalue(L->stack + lim); /* erase new segment */
 167     L->stacksize = newsize;
 168     L->stack_last = L->stack + newsize - EXTRA_STACK;
 169     correctstack(L, oldstack);
 170 }
 171
 172
 173 void luaD_growstack(lua_State *L, int n) {
 174     int size = L->stacksize;
 175     if (size > LUAI_MAXSTACK)  /* error after extra size? */
 176         luaD_throw(L, LUA_ERRERR);
 177     else {
 178         int needed = cast_int(L->top - L->stack) + n + EXTRA_STACK;
 179         int newsize = 2 * size;
 180         if (newsize > LUAI_MAXSTACK) newsize = LUAI_MAXSTACK;
 181         if (newsize < needed) newsize = needed;
 182         if (newsize > LUAI_MAXSTACK) {  /* stack overflow? */
 183             luaD_reallocstack(L, ERRORSTACKSIZE);
 184             luaG_runerror(L, "stack overflow");
 185         } else
 186             luaD_reallocstack(L, newsize);
 187     }
 188 }
 189
 190
 191 static int stackinuse(lua_State *L) {
 192     CallInfo *ci;
 193     StkId lim = L->top;
 194     for (ci = L->ci; ci != NULL; ci = ci->previous) {
 195         lua_assert(ci->top <= L->stack_last);
 196         if (lim < ci->top) lim = ci->top;
 197     }
 198     return cast_int(lim - L->stack) + 1;  /* part of stack in use */
 199 }
 200
 201
 202 void luaD_shrinkstack(lua_State *L) {
 203     int inuse = stackinuse(L);
 204     int goodsize = inuse + (inuse / 8) + 2 * EXTRA_STACK;
 205     if (goodsize > LUAI_MAXSTACK) goodsize = LUAI_MAXSTACK;
 206     if (inuse > LUAI_MAXSTACK ||  /* handling stack overflow? */
 207             goodsize >= L->stacksize)  /* would grow instead of shrink? */
 208         condmovestack(L);  /* don't change stack (change only for debugging) */
 209     else
 210         luaD_reallocstack(L, goodsize);  /* shrink it */
 211 }
 212
 213
 214 void luaD_hook(lua_State *L, int event, int line) {
 215     lua_Hook hook = L->hook;
 216     if (hook && L->allowhook) {
 217         CallInfo *ci = L->ci;
 218         ptrdiff_t top = savestack(L, L->top);
 219         ptrdiff_t ci_top = savestack(L, ci->top);
 220         lua_Debug ar;
 221         ar.event = event;
 222         ar.currentline = line;
 223         ar.i_ci = ci;
 224         luaD_checkstack(L, LUA_MINSTACK);  /* ensure minimum stack size */
 225         ci->top = L->top + LUA_MINSTACK;
 226         lua_assert(ci->top <= L->stack_last);
 227         L->allowhook = 0;  /* cannot call hooks inside a hook */
 228         ci->callstatus |= CIST_HOOKED;
 229         lua_unlock(L);
 230         (*hook)(L, &ar);
 231         lua_lock(L);
 232         lua_assert(!L->allowhook);
 233         L->allowhook = 1;
 234         ci->top = restorestack(L, ci_top);
 235         L->top = restorestack(L, top);
 236         ci->callstatus &= ~CIST_HOOKED;
 237     }
 238 }
 239
 240
 241 static void callhook(lua_State *L, CallInfo *ci) {
 242     int hook = LUA_HOOKCALL;
 243     ci->u.l.savedpc++;  /* hooks assume 'pc' is already incremented */
 244     if (isLua(ci->previous) &&
 245             GET_OPCODE(*(ci->previous->u.l.savedpc - 1)) == OP_TAILCALL) {
 246         ci->callstatus |= CIST_TAIL;
 247         hook = LUA_HOOKTAILCALL;
 248     }
 249     luaD_hook(L, hook, -1);
 250     ci->u.l.savedpc--;  /* correct 'pc' */
 251 }
 252
 253
 254 static StkId adjust_varargs(lua_State *L, Proto *p, int actual) {
 255     int i;
 256     int nfixargs = p->numparams;
 257     StkId base, fixed;
 258     lua_assert(actual >= nfixargs);
 259     /* move fixed parameters to final position */
 260     fixed = L->top - actual;  /* first fixed argument */
 261     base = L->top;  /* final position of first argument */
 262     for (i = 0; i < nfixargs; i++) {
 263         setobjs2s(L, L->top++, fixed + i);
 264         setnilvalue(fixed + i);
 265     }
 266     return base;
 267 }
 268
 269
 270 static StkId tryfuncTM(lua_State *L, StkId func) {
 271     const TValue *tm = luaT_gettmbyobj(L, func, TM_CALL);
 272     StkId p;
 273     ptrdiff_t funcr = savestack(L, func);
 274     if (!ttisfunction(tm))
 275         luaG_typeerror(L, func, "call");
 276     /* Open a hole inside the stack at `func' */
 277     for (p = L->top; p > func; p--) setobjs2s(L, p, p - 1);
 278     incr_top(L);
 279     func = restorestack(L, funcr);  /* previous call may change stack */
 280     setobj2s(L, func, tm);  /* tag method is the new function to be called */
 281     return func;
 282 }
 283
 284
 285
 286 #define next_ci(L) (L->ci = (L->ci->next ? L->ci->next : luaE_extendCI(L)))
 287
 288
 289 /*
 290 ** returns true if function has been executed (C function)
 291 */
 292 int luaD_precall(lua_State *L, StkId func, int nresults) {
 293     lua_CFunction f;
 294     CallInfo *ci;
 295     int n;  /* number of arguments (Lua) or returns (C) */
 296     ptrdiff_t funcr = savestack(L, func);
 297     switch (ttype(func)) {
 298         case LUA_TLCF:  /* light C function */
 299             f = fvalue(func);
 300             goto Cfunc;
 301         case LUA_TCCL: {  /* C closure */
 302             f = clCvalue(func)->f;
 303 Cfunc:
 304             luaD_checkstack(L, LUA_MINSTACK);  /* ensure minimum stack size */
 305             ci = next_ci(L);  /* now 'enter' new function */
 306             ci->nresults = nresults;
 307             ci->func = restorestack(L, funcr);
 308             ci->top = L->top + LUA_MINSTACK;
 309             lua_assert(ci->top <= L->stack_last);
 310             ci->callstatus = 0;
 311             luaC_checkGC(L);  /* stack grow uses memory */
 312             if (L->hookmask & LUA_MASKCALL)
 313                 luaD_hook(L, LUA_HOOKCALL, -1);
 314             lua_unlock(L);
 315             n = (*f)(L);  /* do the actual call */
 316             lua_lock(L);
 317             api_checknelems(L, n);
 318             luaD_poscall(L, L->top - n);
 319             return 1;
 320         }
 321         case LUA_TLCL: {  /* Lua function: prepare its call */
 322             StkId base;
 323             Proto *p = clLvalue(func)->p;
 324             luaD_checkstack(L, p->maxstacksize);
 325             func = restorestack(L, funcr);
 326             n = cast_int(L->top - func) - 1;  /* number of real arguments */
 327             for (; n < p->numparams; n++)
 328                 setnilvalue(L->top++);  /* complete missing arguments */
 329             base = (!p->is_vararg) ? func + 1 : adjust_varargs(L, p, n);
 330             ci = next_ci(L);  /* now 'enter' new function */
 331             ci->nresults = nresults;
 332             ci->func = func;
 333             ci->u.l.base = base;
 334             ci->top = base + p->maxstacksize;
 335             lua_assert(ci->top <= L->stack_last);
 336             ci->u.l.savedpc = p->code;  /* starting point */
 337             ci->callstatus = CIST_LUA;
 338             L->top = ci->top;
 339             luaC_checkGC(L);  /* stack grow uses memory */
 340             if (L->hookmask & LUA_MASKCALL)
 341                 callhook(L, ci);
 342             return 0;
 343         }
 344         default: {  /* not a function */
 345             func = tryfuncTM(L, func);  /* retry with 'function' tag method */
 346             return luaD_precall(L, func, nresults);  /* now it must be a function */
 347         }
 348     }
 349 }
 350
 351
 352 int luaD_poscall(lua_State *L, StkId firstResult) {
 353     StkId res;
 354     int wanted, i;
 355     CallInfo *ci = L->ci;
 356     if (L->hookmask & (LUA_MASKRET | LUA_MASKLINE)) {
 357         if (L->hookmask & LUA_MASKRET) {
 358             ptrdiff_t fr = savestack(L, firstResult);  /* hook may change stack */
 359             luaD_hook(L, LUA_HOOKRET, -1);
 360             firstResult = restorestack(L, fr);
 361         }
 362         L->oldpc = ci->previous->u.l.savedpc;  /* 'oldpc' for caller function */
 363     }
 364     res = ci->func;  /* res == final position of 1st result */
 365     wanted = ci->nresults;
 366     L->ci = ci = ci->previous;  /* back to caller */
 367     /* move results to correct place */
 368     for (i = wanted; i != 0 && firstResult < L->top; i--)
 369         setobjs2s(L, res++, firstResult++);
 370     while (i-- > 0)
 371         setnilvalue(res++);
 372     L->top = res;
 373     return (wanted - LUA_MULTRET);  /* 0 iff wanted == LUA_MULTRET */
 374 }
 375
 376
 377 /*
 378 ** Call a function (C or Lua). The function to be called is at *func.
 379 ** The arguments are on the stack, right after the function.
 380 ** When returns, all the results are on the stack, starting at the original
 381 ** function position.
 382 */
 383 void luaD_call(lua_State *L, StkId func, int nResults, int allowyield) {
 384     if (++L->nCcalls >= LUAI_MAXCCALLS) {
 385         if (L->nCcalls == LUAI_MAXCCALLS)
 386             luaG_runerror(L, "C stack overflow");
 387         else if (L->nCcalls >= (LUAI_MAXCCALLS + (LUAI_MAXCCALLS >> 3)))
 388             luaD_throw(L, LUA_ERRERR);  /* error while handing stack error */
 389     }
 390     if (!allowyield) L->nny++;
 391     if (!luaD_precall(L, func, nResults))  /* is a Lua function? */
 392         luaV_execute(L);  /* call it */
 393     if (!allowyield) L->nny--;
 394     L->nCcalls--;
 395 }
 396
 397
 398 static void finishCcall(lua_State *L) {
 399     CallInfo *ci = L->ci;
 400     int n;
 401     lua_assert(ci->u.c.k != NULL);  /* must have a continuation */
 402     lua_assert(L->nny == 0);
 403     if (ci->callstatus & CIST_YPCALL) {  /* was inside a pcall? */
 404         ci->callstatus &= ~CIST_YPCALL;  /* finish 'lua_pcall' */
 405         L->errfunc = ci->u.c.old_errfunc;
 406     }
 407     /* finish 'lua_callk'/'lua_pcall' */
 408     adjustresults(L, ci->nresults);
 409     /* call continuation function */
 410     if (!(ci->callstatus & CIST_STAT))  /* no call status? */
 411         ci->u.c.status = LUA_YIELD;  /* 'default' status */
 412     lua_assert(ci->u.c.status != LUA_OK);
 413     ci->callstatus = (ci->callstatus & ~(CIST_YPCALL | CIST_STAT)) | CIST_YIELDED;
 414     lua_unlock(L);
 415     n = (*ci->u.c.k)(L);
 416     lua_lock(L);
 417     api_checknelems(L, n);
 418     /* finish 'luaD_precall' */
 419     luaD_poscall(L, L->top - n);
 420 }
 421
 422
 423 static void unroll(lua_State *L, void *ud) {
 424     UNUSED(ud);
 425     for (;;) {
 426         if (L->ci == &L->base_ci)  /* stack is empty? */
 427             return;  /* coroutine finished normally */
 428         if (!isLua(L->ci))  /* C function? */
 429             finishCcall(L);
 430         else {  /* Lua function */
 431             luaV_finishOp(L);  /* finish interrupted instruction */
 432             luaV_execute(L);  /* execute down to higher C 'boundary' */
 433         }
 434     }
 435 }
 436
 437
 438 /*
 439 ** check whether thread has a suspended protected call
 440 */
 441 static CallInfo *findpcall(lua_State *L) {
 442     CallInfo *ci;
 443     for (ci = L->ci; ci != NULL; ci = ci->previous) {  /* search for a pcall */
 444         if (ci->callstatus & CIST_YPCALL)
 445             return ci;
 446     }
 447     return NULL;  /* no pending pcall */
 448 }
 449
 450
 451 static int recover(lua_State *L, int status) {
 452     StkId oldtop;
 453     CallInfo *ci = findpcall(L);
 454     if (ci == NULL) return 0;  /* no recovery point */
 455     /* "finish" luaD_pcall */
 456     oldtop = restorestack(L, ci->extra);
 457     luaF_close(L, oldtop);
 458     seterrorobj(L, status, oldtop);
 459     L->ci = ci;
 460     L->allowhook = ci->u.c.old_allowhook;
 461     L->nny = 0;  /* should be zero to be yieldable */
 462     luaD_shrinkstack(L);
 463     L->errfunc = ci->u.c.old_errfunc;
 464     ci->callstatus |= CIST_STAT;  /* call has error status */
 465     ci->u.c.status = status;  /* (here it is) */
 466     return 1;  /* continue running the coroutine */
 467 }
 468
 469
 470 /*
 471 ** signal an error in the call to 'resume', not in the execution of the
 472 ** coroutine itself. (Such errors should not be handled by any coroutine
 473 ** error handler and should not kill the coroutine.)
 474 */
 475 static l_noret resume_error(lua_State *L, const char *msg, StkId firstArg) {
 476     L->top = firstArg;  /* remove args from the stack */
 477     setsvalue2s(L, L->top, luaS_new(L, msg));  /* push error message */
 478     api_incr_top(L);
 479     luaD_throw(L, -1);  /* jump back to 'lua_resume' */
 480 }
 481
 482
 483 /*
 484 ** do the work for 'lua_resume' in protected mode
 485 */
 486 static void resume(lua_State *L, void *ud) {
 487     int nCcalls = L->nCcalls;
 488     StkId firstArg = cast(StkId, ud);
 489     CallInfo *ci = L->ci;
 490     if (nCcalls >= LUAI_MAXCCALLS)
 491         resume_error(L, "C stack overflow", firstArg);
 492     if (L->status == LUA_OK) {  /* may be starting a coroutine */
 493         if (ci != &L->base_ci)  /* not in base level? */
 494             resume_error(L, "cannot resume non-suspended coroutine", firstArg);
 495         /* coroutine is in base level; start running it */
 496         if (!luaD_precall(L, firstArg - 1, LUA_MULTRET))  /* Lua function? */
 497             luaV_execute(L);  /* call it */
 498     } else if (L->status != LUA_YIELD)
 499         resume_error(L, "cannot resume dead coroutine", firstArg);
 500     else {  /* resuming from previous yield */
 501         L->status = LUA_OK;
 502         ci->func = restorestack(L, ci->extra);
 503         if (isLua(ci))  /* yielded inside a hook? */
 504             luaV_execute(L);  /* just continue running Lua code */
 505         else {  /* 'common' yield */
 506             if (ci->u.c.k != NULL) {  /* does it have a continuation? */
 507                 int n;
 508                 ci->u.c.status = LUA_YIELD;  /* 'default' status */
 509                 ci->callstatus |= CIST_YIELDED;
 510                 lua_unlock(L);
 511                 n = (*ci->u.c.k)(L);  /* call continuation */
 512                 lua_lock(L);
 513                 api_checknelems(L, n);
 514                 firstArg = L->top - n;  /* yield results come from continuation */
 515             }
 516             luaD_poscall(L, firstArg);  /* finish 'luaD_precall' */
 517         }
 518         unroll(L, NULL);
 519     }
 520     lua_assert(nCcalls == L->nCcalls);
 521 }
 522
 523
 524 LUA_API int lua_resume(lua_State *L, lua_State *from, int nargs) {
 525     int status;
 526     lua_lock(L);
 527     luai_userstateresume(L, nargs);
 528     L->nCcalls = (from) ? from->nCcalls + 1 : 1;
 529     L->nny = 0;  /* allow yields */
 530     api_checknelems(L, (L->status == LUA_OK) ? nargs + 1 : nargs);
 531     status = luaD_rawrunprotected(L, resume, L->top - nargs);
 532     if (status == -1)  /* error calling 'lua_resume'? */
 533         status = LUA_ERRRUN;
 534     else {  /* yield or regular error */
 535         while (status != LUA_OK && status != LUA_YIELD) {  /* error? */
 536             if (recover(L, status))  /* recover point? */
 537                 status = luaD_rawrunprotected(L, unroll, NULL);  /* run continuation */
 538             else {  /* unrecoverable error */
 539                 L->status = cast_byte(status);  /* mark thread as `dead' */
 540                 seterrorobj(L, status, L->top);
 541                 L->ci->top = L->top;
 542                 break;
 543             }
 544         }
 545         lua_assert(status == L->status);
 546     }
 547     L->nny = 1;  /* do not allow yields */
 548     L->nCcalls--;
 549     lua_assert(L->nCcalls == ((from) ? from->nCcalls : 0));
 550     lua_unlock(L);
 551     return status;
 552 }
 553
 554
 555 LUA_API int lua_yieldk(lua_State *L, int nresults, int ctx, lua_CFunction k) {
 556     CallInfo *ci = L->ci;
 557     luai_userstateyield(L, nresults);
 558     lua_lock(L);
 559     api_checknelems(L, nresults);
 560     if (L->nny > 0) {
 561         if (L != G(L)->mainthread)
 562             luaG_runerror(L, "attempt to yield across a C-call boundary");
 563         else
 564             luaG_runerror(L, "attempt to yield from outside a coroutine");
 565     }
 566     L->status = LUA_YIELD;
 567     ci->extra = savestack(L, ci->func);  /* save current 'func' */
 568     if (isLua(ci)) {  /* inside a hook? */
 569         api_check(L, k == NULL, "hooks cannot continue after yielding");
 570     } else {
 571         if ((ci->u.c.k = k) != NULL)  /* is there a continuation? */
 572             ci->u.c.ctx = ctx;  /* save context */
 573         ci->func = L->top - nresults - 1;  /* protect stack below results */
 574         luaD_throw(L, LUA_YIELD);
 575     }
 576     lua_assert(ci->callstatus & CIST_HOOKED);  /* must be inside a hook */
 577     lua_unlock(L);
 578     return 0;  /* return to 'luaD_hook' */
 579 }
 580
 581
 582 int luaD_pcall(lua_State *L, Pfunc func, void *u,
 583                ptrdiff_t old_top, ptrdiff_t ef) {
 584     int status;
 585     CallInfo *old_ci = L->ci;
 586     lu_byte old_allowhooks = L->allowhook;
 587     unsigned short old_nny = L->nny;
 588     ptrdiff_t old_errfunc = L->errfunc;
 589     L->errfunc = ef;
 590     status = luaD_rawrunprotected(L, func, u);
 591     if (status != LUA_OK) {  /* an error occurred? */
 592         StkId oldtop = restorestack(L, old_top);
 593         luaF_close(L, oldtop);  /* close possible pending closures */
 594         seterrorobj(L, status, oldtop);
 595         L->ci = old_ci;
 596         L->allowhook = old_allowhooks;
 597         L->nny = old_nny;
 598         luaD_shrinkstack(L);
 599     }
 600     L->errfunc = old_errfunc;
 601     return status;
 602 }
 603
 604
 605
 606 /*
 607 ** Execute a protected parser.
 608 */
 609 struct SParser {  /* data to `f_parser' */
 610     ZIO *z;
 611     Mbuffer buff;  /* dynamic structure used by the scanner */
 612     Dyndata dyd;  /* dynamic structures used by the parser */
 613     const char *mode;
 614     const char *name;
 615 };
 616
 617
 618 static void checkmode(lua_State *L, const char *mode, const char *x) {
 619     if (mode && strchr(mode, x[0]) == NULL) {
 620         luaO_pushfstring(L,
 621                          "attempt to load a %s chunk (mode is " LUA_QS ")", x, mode);
 622         luaD_throw(L, LUA_ERRSYNTAX);
 623     }
 624 }
 625
 626
 627 static void f_parser(lua_State *L, void *ud) {
 628     int i;
 629     Closure *cl;
 630     struct SParser *p = cast(struct SParser *, ud);
 631     int c = zgetc(p->z);  /* read first character */
 632     if (c == LUA_SIGNATURE[0]) {
 633         checkmode(L, p->mode, "binary");
 634         cl = luaU_undump(L, p->z, &p->buff, p->name);
 635     } else {
 636         checkmode(L, p->mode, "text");
 637         cl = luaY_parser(L, p->z, &p->buff, &p->dyd, p->name, c);
 638     }
 639     lua_assert(cl->l.nupvalues == cl->l.p->sizeupvalues);
 640     for (i = 0; i < cl->l.nupvalues; i++) {  /* initialize upvalues */
 641         UpVal *up = luaF_newupval(L);
 642         cl->l.upvals[i] = up;
 643         luaC_objbarrier(L, cl, up);
 644     }
 645 }
 646
 647
 648 int luaD_protectedparser(lua_State *L, ZIO *z, const char *name,
 649                          const char *mode) {
 650     struct SParser p;
 651     int status;
 652     L->nny++;  /* cannot yield during parsing */
 653     p.z = z;
 654     p.name = name;
 655     p.mode = mode;
 656     p.dyd.actvar.arr = NULL;
 657     p.dyd.actvar.size = 0;
 658     p.dyd.gt.arr = NULL;
 659     p.dyd.gt.size = 0;
 660     p.dyd.label.arr = NULL;
 661     p.dyd.label.size = 0;
 662     luaZ_initbuffer(L, &p.buff);
 663     status = luaD_pcall(L, f_parser, &p, savestack(L, L->top), L->errfunc);
 664     luaZ_freebuffer(L, &p.buff);
 665     luaM_freearray(L, p.dyd.actvar.arr, p.dyd.actvar.size);
 666     luaM_freearray(L, p.dyd.gt.arr, p.dyd.gt.size);
 667     luaM_freearray(L, p.dyd.label.arr, p.dyd.label.size);
 668     L->nny--;
 669     return status;
 670 }
 671
 672