1 /* $NetBSD: ldo.c,v 1.4 2015/10/08 13:21:00 mbalmer Exp $ */ 2 3 /* 4 ** Id: ldo.c,v 2.138 2015/05/22 17:48:19 roberto Exp 5 ** Stack and Call structure of Lua 6 ** See Copyright Notice in lua.h 7 */ 8 9 #define ldo_c 10 #define LUA_CORE 11 12 #include "lprefix.h" 13 14 15 #ifndef _KERNEL 16 #include <setjmp.h> 17 #include <stdlib.h> 18 #include <string.h> 19 #endif 20 21 #include "lua.h" 22 23 #include "lapi.h" 24 #include "ldebug.h" 25 #include "ldo.h" 26 #include "lfunc.h" 27 #include "lgc.h" 28 #include "lmem.h" 29 #include "lobject.h" 30 #include "lopcodes.h" 31 #include "lparser.h" 32 #include "lstate.h" 33 #include "lstring.h" 34 #include "ltable.h" 35 #include "ltm.h" 36 #include "lundump.h" 37 #include "lvm.h" 38 #include "lzio.h" 39 40 41 42 #define errorstatus(s) ((s) > LUA_YIELD) 43 44 45 /* 46 ** {====================================================== 47 ** Error-recovery functions 48 ** ======================================================= 49 */ 50 51 /* 52 ** LUAI_THROW/LUAI_TRY define how Lua does exception handling. By 53 ** default, Lua handles errors with exceptions when compiling as 54 ** C++ code, with _longjmp/_setjmp when asked to use them, and with 55 ** longjmp/setjmp otherwise. 56 */ 57 #if !defined(LUAI_THROW) /* { */ 58 59 #if defined(__cplusplus) && !defined(LUA_USE_LONGJMP) /* { */ 60 61 /* C++ exceptions */ 62 #define LUAI_THROW(L,c) throw(c) 63 #define LUAI_TRY(L,c,a) \ 64 try { a } catch(...) { if ((c)->status == 0) (c)->status = -1; } 65 #define luai_jmpbuf int /* dummy variable */ 66 67 #elif defined(LUA_USE_POSIX) /* }{ */ 68 69 /* in POSIX, try _longjmp/_setjmp (more efficient) */ 70 #define LUAI_THROW(L,c) _longjmp((c)->b, 1) 71 #define LUAI_TRY(L,c,a) if (_setjmp((c)->b) == 0) { a } 72 #define luai_jmpbuf jmp_buf 73 74 #else /* }{ */ 75 76 /* ISO C handling with long jumps */ 77 #define LUAI_THROW(L,c) longjmp((c)->b, 1) 78 #define LUAI_TRY(L,c,a) if (setjmp((c)->b) == 0) { a } 79 #define luai_jmpbuf jmp_buf 80 81 #endif /* } */ 82 83 #endif /* } */ 84 85 86 87 /* chain list of long jump buffers */ 88 struct lua_longjmp { 89 struct lua_longjmp *previous; 90 luai_jmpbuf b; 91 volatile int status; /* error code */ 92 }; 93 94 95 static void seterrorobj (lua_State *L, int errcode, StkId oldtop) { 96 switch (errcode) { 97 case LUA_ERRMEM: { /* memory error? */ 98 setsvalue2s(L, oldtop, G(L)->memerrmsg); /* reuse preregistered msg. */ 99 break; 100 } 101 case LUA_ERRERR: { 102 setsvalue2s(L, oldtop, luaS_newliteral(L, "error in error handling")); 103 break; 104 } 105 default: { 106 setobjs2s(L, oldtop, L->top - 1); /* error message on current top */ 107 break; 108 } 109 } 110 L->top = oldtop + 1; 111 } 112 113 114 l_noret luaD_throw (lua_State *L, int errcode) { 115 if (L->errorJmp) { /* thread has an error handler? */ 116 L->errorJmp->status = errcode; /* set status */ 117 LUAI_THROW(L, L->errorJmp); /* jump to it */ 118 } 119 else { /* thread has no error handler */ 120 global_State *g = G(L); 121 L->status = cast_byte(errcode); /* mark it as dead */ 122 if (g->mainthread->errorJmp) { /* main thread has a handler? */ 123 setobjs2s(L, g->mainthread->top++, L->top - 1); /* copy error obj. */ 124 luaD_throw(g->mainthread, errcode); /* re-throw in main thread */ 125 } 126 else { /* no handler at all; abort */ 127 if (g->panic) { /* panic function? */ 128 seterrorobj(L, errcode, L->top); /* assume EXTRA_STACK */ 129 if (L->ci->top < L->top) 130 L->ci->top = L->top; /* pushing msg. can break this invariant */ 131 lua_unlock(L); 132 g->panic(L); /* call panic function (last chance to jump out) */ 133 } 134 abort(); 135 } 136 } 137 } 138 139 140 int luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud) { 141 unsigned short oldnCcalls = L->nCcalls; 142 struct lua_longjmp lj; 143 lj.status = LUA_OK; 144 lj.previous = L->errorJmp; /* chain new error handler */ 145 L->errorJmp = &lj; 146 LUAI_TRY(L, &lj, 147 (*f)(L, ud); 148 ); 149 L->errorJmp = lj.previous; /* restore old error handler */ 150 L->nCcalls = oldnCcalls; 151 return lj.status; 152 } 153 154 /* }====================================================== */ 155 156 157 static void correctstack (lua_State *L, TValue *oldstack) { 158 CallInfo *ci; 159 UpVal *up; 160 L->top = (L->top - oldstack) + L->stack; 161 for (up = L->openupval; up != NULL; up = up->u.open.next) 162 up->v = (up->v - oldstack) + L->stack; 163 for (ci = L->ci; ci != NULL; ci = ci->previous) { 164 ci->top = (ci->top - oldstack) + L->stack; 165 ci->func = (ci->func - oldstack) + L->stack; 166 if (isLua(ci)) 167 ci->u.l.base = (ci->u.l.base - oldstack) + L->stack; 168 } 169 } 170 171 172 /* some space for error handling */ 173 #define ERRORSTACKSIZE (LUAI_MAXSTACK + 200) 174 175 176 void luaD_reallocstack (lua_State *L, int newsize) { 177 TValue *oldstack = L->stack; 178 int lim = L->stacksize; 179 lua_assert(newsize <= LUAI_MAXSTACK || newsize == ERRORSTACKSIZE); 180 lua_assert(L->stack_last - L->stack == L->stacksize - EXTRA_STACK); 181 luaM_reallocvector(L, L->stack, L->stacksize, newsize, TValue); 182 for (; lim < newsize; lim++) 183 setnilvalue(L->stack + lim); /* erase new segment */ 184 L->stacksize = newsize; 185 L->stack_last = L->stack + newsize - EXTRA_STACK; 186 correctstack(L, oldstack); 187 } 188 189 190 void luaD_growstack (lua_State *L, int n) { 191 int size = L->stacksize; 192 if (size > LUAI_MAXSTACK) /* error after extra size? */ 193 luaD_throw(L, LUA_ERRERR); 194 else { 195 int needed = cast_int(L->top - L->stack) + n + EXTRA_STACK; 196 int newsize = 2 * size; 197 if (newsize > LUAI_MAXSTACK) newsize = LUAI_MAXSTACK; 198 if (newsize < needed) newsize = needed; 199 if (newsize > LUAI_MAXSTACK) { /* stack overflow? */ 200 luaD_reallocstack(L, ERRORSTACKSIZE); 201 luaG_runerror(L, "stack overflow"); 202 } 203 else 204 luaD_reallocstack(L, newsize); 205 } 206 } 207 208 209 static int stackinuse (lua_State *L) { 210 CallInfo *ci; 211 StkId lim = L->top; 212 for (ci = L->ci; ci != NULL; ci = ci->previous) { 213 lua_assert(ci->top <= L->stack_last); 214 if (lim < ci->top) lim = ci->top; 215 } 216 return cast_int(lim - L->stack) + 1; /* part of stack in use */ 217 } 218 219 220 void luaD_shrinkstack (lua_State *L) { 221 int inuse = stackinuse(L); 222 int goodsize = inuse + (inuse / 8) + 2*EXTRA_STACK; 223 if (goodsize > LUAI_MAXSTACK) goodsize = LUAI_MAXSTACK; 224 if (L->stacksize > LUAI_MAXSTACK) /* was handling stack overflow? */ 225 luaE_freeCI(L); /* free all CIs (list grew because of an error) */ 226 else 227 luaE_shrinkCI(L); /* shrink list */ 228 if (inuse > LUAI_MAXSTACK || /* still handling stack overflow? */ 229 goodsize >= L->stacksize) /* would grow instead of shrink? */ 230 condmovestack(L); /* don't change stack (change only for debugging) */ 231 else 232 luaD_reallocstack(L, goodsize); /* shrink it */ 233 } 234 235 236 void luaD_hook (lua_State *L, int event, int line) { 237 lua_Hook hook = L->hook; 238 if (hook && L->allowhook) { 239 CallInfo *ci = L->ci; 240 ptrdiff_t top = savestack(L, L->top); 241 ptrdiff_t ci_top = savestack(L, ci->top); 242 lua_Debug ar; 243 ar.event = event; 244 ar.currentline = line; 245 ar.i_ci = ci; 246 luaD_checkstack(L, LUA_MINSTACK); /* ensure minimum stack size */ 247 ci->top = L->top + LUA_MINSTACK; 248 lua_assert(ci->top <= L->stack_last); 249 L->allowhook = 0; /* cannot call hooks inside a hook */ 250 ci->callstatus |= CIST_HOOKED; 251 lua_unlock(L); 252 (*hook)(L, &ar); 253 lua_lock(L); 254 lua_assert(!L->allowhook); 255 L->allowhook = 1; 256 ci->top = restorestack(L, ci_top); 257 L->top = restorestack(L, top); 258 ci->callstatus &= ~CIST_HOOKED; 259 } 260 } 261 262 263 static void callhook (lua_State *L, CallInfo *ci) { 264 int hook = LUA_HOOKCALL; 265 ci->u.l.savedpc++; /* hooks assume 'pc' is already incremented */ 266 if (isLua(ci->previous) && 267 GET_OPCODE(*(ci->previous->u.l.savedpc - 1)) == OP_TAILCALL) { 268 ci->callstatus |= CIST_TAIL; 269 hook = LUA_HOOKTAILCALL; 270 } 271 luaD_hook(L, hook, -1); 272 ci->u.l.savedpc--; /* correct 'pc' */ 273 } 274 275 276 static StkId adjust_varargs (lua_State *L, Proto *p, int actual) { 277 int i; 278 int nfixargs = p->numparams; 279 StkId base, fixed; 280 lua_assert(actual >= nfixargs); 281 /* move fixed parameters to final position */ 282 luaD_checkstack(L, p->maxstacksize); /* check again for new 'base' */ 283 fixed = L->top - actual; /* first fixed argument */ 284 base = L->top; /* final position of first argument */ 285 for (i=0; i<nfixargs; i++) { 286 setobjs2s(L, L->top++, fixed + i); 287 setnilvalue(fixed + i); 288 } 289 return base; 290 } 291 292 293 /* 294 ** Check whether __call metafield of 'func' is a function. If so, put 295 ** it in stack below original 'func' so that 'luaD_precall' can call 296 ** it. Raise an error if __call metafield is not a function. 297 */ 298 static void tryfuncTM (lua_State *L, StkId func) { 299 const TValue *tm = luaT_gettmbyobj(L, func, TM_CALL); 300 StkId p; 301 if (!ttisfunction(tm)) 302 luaG_typeerror(L, func, "call"); 303 /* Open a hole inside the stack at 'func' */ 304 for (p = L->top; p > func; p--) 305 setobjs2s(L, p, p-1); 306 L->top++; /* slot ensured by caller */ 307 setobj2s(L, func, tm); /* tag method is the new function to be called */ 308 } 309 310 311 312 #define next_ci(L) (L->ci = (L->ci->next ? L->ci->next : luaE_extendCI(L))) 313 314 315 /* 316 ** returns true if function has been executed (C function) 317 */ 318 int luaD_precall (lua_State *L, StkId func, int nresults) { 319 lua_CFunction f; 320 CallInfo *ci; 321 int n; /* number of arguments (Lua) or returns (C) */ 322 ptrdiff_t funcr = savestack(L, func); 323 switch (ttype(func)) { 324 case LUA_TLCF: /* light C function */ 325 f = fvalue(func); 326 goto Cfunc; 327 case LUA_TCCL: { /* C closure */ 328 f = clCvalue(func)->f; 329 Cfunc: 330 luaC_checkGC(L); /* stack grow uses memory */ 331 luaD_checkstack(L, LUA_MINSTACK); /* ensure minimum stack size */ 332 ci = next_ci(L); /* now 'enter' new function */ 333 ci->nresults = nresults; 334 ci->func = restorestack(L, funcr); 335 ci->top = L->top + LUA_MINSTACK; 336 lua_assert(ci->top <= L->stack_last); 337 ci->callstatus = 0; 338 if (L->hookmask & LUA_MASKCALL) 339 luaD_hook(L, LUA_HOOKCALL, -1); 340 lua_unlock(L); 341 n = (*f)(L); /* do the actual call */ 342 lua_lock(L); 343 api_checknelems(L, n); 344 luaD_poscall(L, L->top - n, n); 345 return 1; 346 } 347 case LUA_TLCL: { /* Lua function: prepare its call */ 348 StkId base; 349 Proto *p = clLvalue(func)->p; 350 n = cast_int(L->top - func) - 1; /* number of real arguments */ 351 luaC_checkGC(L); /* stack grow uses memory */ 352 luaD_checkstack(L, p->maxstacksize); 353 for (; n < p->numparams; n++) 354 setnilvalue(L->top++); /* complete missing arguments */ 355 if (!p->is_vararg) { 356 func = restorestack(L, funcr); 357 base = func + 1; 358 } 359 else { 360 base = adjust_varargs(L, p, n); 361 func = restorestack(L, funcr); /* previous call can change stack */ 362 } 363 ci = next_ci(L); /* now 'enter' new function */ 364 ci->nresults = nresults; 365 ci->func = func; 366 ci->u.l.base = base; 367 ci->top = base + p->maxstacksize; 368 lua_assert(ci->top <= L->stack_last); 369 ci->u.l.savedpc = p->code; /* starting point */ 370 ci->callstatus = CIST_LUA; 371 L->top = ci->top; 372 if (L->hookmask & LUA_MASKCALL) 373 callhook(L, ci); 374 return 0; 375 } 376 default: { /* not a function */ 377 luaD_checkstack(L, 1); /* ensure space for metamethod */ 378 func = restorestack(L, funcr); /* previous call may change stack */ 379 tryfuncTM(L, func); /* try to get '__call' metamethod */ 380 return luaD_precall(L, func, nresults); /* now it must be a function */ 381 } 382 } 383 } 384 385 386 int luaD_poscall (lua_State *L, StkId firstResult, int nres) { 387 StkId res; 388 int wanted, i; 389 CallInfo *ci = L->ci; 390 if (L->hookmask & (LUA_MASKRET | LUA_MASKLINE)) { 391 if (L->hookmask & LUA_MASKRET) { 392 ptrdiff_t fr = savestack(L, firstResult); /* hook may change stack */ 393 luaD_hook(L, LUA_HOOKRET, -1); 394 firstResult = restorestack(L, fr); 395 } 396 L->oldpc = ci->previous->u.l.savedpc; /* 'oldpc' for caller function */ 397 } 398 res = ci->func; /* res == final position of 1st result */ 399 wanted = ci->nresults; 400 L->ci = ci->previous; /* back to caller */ 401 /* move results to correct place */ 402 for (i = wanted; i != 0 && nres-- > 0; i--) 403 setobjs2s(L, res++, firstResult++); 404 while (i-- > 0) 405 setnilvalue(res++); 406 L->top = res; 407 return (wanted - LUA_MULTRET); /* 0 iff wanted == LUA_MULTRET */ 408 } 409 410 411 /* 412 ** Call a function (C or Lua). The function to be called is at *func. 413 ** The arguments are on the stack, right after the function. 414 ** When returns, all the results are on the stack, starting at the original 415 ** function position. 416 */ 417 void luaD_call (lua_State *L, StkId func, int nResults, int allowyield) { 418 if (++L->nCcalls >= LUAI_MAXCCALLS) { 419 if (L->nCcalls == LUAI_MAXCCALLS) 420 luaG_runerror(L, "C stack overflow"); 421 else if (L->nCcalls >= (LUAI_MAXCCALLS + (LUAI_MAXCCALLS>>3))) 422 luaD_throw(L, LUA_ERRERR); /* error while handing stack error */ 423 } 424 if (!allowyield) L->nny++; 425 if (!luaD_precall(L, func, nResults)) /* is a Lua function? */ 426 luaV_execute(L); /* call it */ 427 if (!allowyield) L->nny--; 428 L->nCcalls--; 429 } 430 431 432 /* 433 ** Completes the execution of an interrupted C function, calling its 434 ** continuation function. 435 */ 436 static void finishCcall (lua_State *L, int status) { 437 CallInfo *ci = L->ci; 438 int n; 439 /* must have a continuation and must be able to call it */ 440 lua_assert(ci->u.c.k != NULL && L->nny == 0); 441 /* error status can only happen in a protected call */ 442 lua_assert((ci->callstatus & CIST_YPCALL) || status == LUA_YIELD); 443 if (ci->callstatus & CIST_YPCALL) { /* was inside a pcall? */ 444 ci->callstatus &= ~CIST_YPCALL; /* finish 'lua_pcall' */ 445 L->errfunc = ci->u.c.old_errfunc; 446 } 447 /* finish 'lua_callk'/'lua_pcall'; CIST_YPCALL and 'errfunc' already 448 handled */ 449 adjustresults(L, ci->nresults); 450 /* call continuation function */ 451 lua_unlock(L); 452 n = (*ci->u.c.k)(L, status, ci->u.c.ctx); 453 lua_lock(L); 454 api_checknelems(L, n); 455 /* finish 'luaD_precall' */ 456 luaD_poscall(L, L->top - n, n); 457 } 458 459 460 /* 461 ** Executes "full continuation" (everything in the stack) of a 462 ** previously interrupted coroutine until the stack is empty (or another 463 ** interruption long-jumps out of the loop). If the coroutine is 464 ** recovering from an error, 'ud' points to the error status, which must 465 ** be passed to the first continuation function (otherwise the default 466 ** status is LUA_YIELD). 467 */ 468 static void unroll (lua_State *L, void *ud) { 469 if (ud != NULL) /* error status? */ 470 finishCcall(L, *(int *)ud); /* finish 'lua_pcallk' callee */ 471 while (L->ci != &L->base_ci) { /* something in the stack */ 472 if (!isLua(L->ci)) /* C function? */ 473 finishCcall(L, LUA_YIELD); /* complete its execution */ 474 else { /* Lua function */ 475 luaV_finishOp(L); /* finish interrupted instruction */ 476 luaV_execute(L); /* execute down to higher C 'boundary' */ 477 } 478 } 479 } 480 481 482 /* 483 ** Try to find a suspended protected call (a "recover point") for the 484 ** given thread. 485 */ 486 static CallInfo *findpcall (lua_State *L) { 487 CallInfo *ci; 488 for (ci = L->ci; ci != NULL; ci = ci->previous) { /* search for a pcall */ 489 if (ci->callstatus & CIST_YPCALL) 490 return ci; 491 } 492 return NULL; /* no pending pcall */ 493 } 494 495 496 /* 497 ** Recovers from an error in a coroutine. Finds a recover point (if 498 ** there is one) and completes the execution of the interrupted 499 ** 'luaD_pcall'. If there is no recover point, returns zero. 500 */ 501 static int recover (lua_State *L, int status) { 502 StkId oldtop; 503 CallInfo *ci = findpcall(L); 504 if (ci == NULL) return 0; /* no recovery point */ 505 /* "finish" luaD_pcall */ 506 oldtop = restorestack(L, ci->extra); 507 luaF_close(L, oldtop); 508 seterrorobj(L, status, oldtop); 509 L->ci = ci; 510 L->allowhook = getoah(ci->callstatus); /* restore original 'allowhook' */ 511 L->nny = 0; /* should be zero to be yieldable */ 512 luaD_shrinkstack(L); 513 L->errfunc = ci->u.c.old_errfunc; 514 return 1; /* continue running the coroutine */ 515 } 516 517 518 /* 519 ** signal an error in the call to 'resume', not in the execution of the 520 ** coroutine itself. (Such errors should not be handled by any coroutine 521 ** error handler and should not kill the coroutine.) 522 */ 523 static l_noret resume_error (lua_State *L, const char *msg, StkId firstArg) { 524 L->top = firstArg; /* remove args from the stack */ 525 setsvalue2s(L, L->top, luaS_new(L, msg)); /* push error message */ 526 api_incr_top(L); 527 luaD_throw(L, -1); /* jump back to 'lua_resume' */ 528 } 529 530 531 /* 532 ** Do the work for 'lua_resume' in protected mode. Most of the work 533 ** depends on the status of the coroutine: initial state, suspended 534 ** inside a hook, or regularly suspended (optionally with a continuation 535 ** function), plus erroneous cases: non-suspended coroutine or dead 536 ** coroutine. 537 */ 538 static void resume (lua_State *L, void *ud) { 539 int nCcalls = L->nCcalls; 540 int n = *(cast(int*, ud)); /* number of arguments */ 541 StkId firstArg = L->top - n; /* first argument */ 542 CallInfo *ci = L->ci; 543 if (nCcalls >= LUAI_MAXCCALLS) 544 resume_error(L, "C stack overflow", firstArg); 545 if (L->status == LUA_OK) { /* may be starting a coroutine */ 546 if (ci != &L->base_ci) /* not in base level? */ 547 resume_error(L, "cannot resume non-suspended coroutine", firstArg); 548 /* coroutine is in base level; start running it */ 549 if (!luaD_precall(L, firstArg - 1, LUA_MULTRET)) /* Lua function? */ 550 luaV_execute(L); /* call it */ 551 } 552 else if (L->status != LUA_YIELD) 553 resume_error(L, "cannot resume dead coroutine", firstArg); 554 else { /* resuming from previous yield */ 555 L->status = LUA_OK; /* mark that it is running (again) */ 556 ci->func = restorestack(L, ci->extra); 557 if (isLua(ci)) /* yielded inside a hook? */ 558 luaV_execute(L); /* just continue running Lua code */ 559 else { /* 'common' yield */ 560 if (ci->u.c.k != NULL) { /* does it have a continuation function? */ 561 lua_unlock(L); 562 n = (*ci->u.c.k)(L, LUA_YIELD, ci->u.c.ctx); /* call continuation */ 563 lua_lock(L); 564 api_checknelems(L, n); 565 firstArg = L->top - n; /* yield results come from continuation */ 566 } 567 luaD_poscall(L, firstArg, n); /* finish 'luaD_precall' */ 568 } 569 unroll(L, NULL); /* run continuation */ 570 } 571 lua_assert(nCcalls == L->nCcalls); 572 } 573 574 575 LUA_API int lua_resume (lua_State *L, lua_State *from, int nargs) { 576 int status; 577 int oldnny = L->nny; /* save "number of non-yieldable" calls */ 578 lua_lock(L); 579 luai_userstateresume(L, nargs); 580 L->nCcalls = (from) ? from->nCcalls + 1 : 1; 581 L->nny = 0; /* allow yields */ 582 api_checknelems(L, (L->status == LUA_OK) ? nargs + 1 : nargs); 583 status = luaD_rawrunprotected(L, resume, &nargs); 584 if (status == -1) /* error calling 'lua_resume'? */ 585 status = LUA_ERRRUN; 586 else { /* continue running after recoverable errors */ 587 while (errorstatus(status) && recover(L, status)) { 588 /* unroll continuation */ 589 status = luaD_rawrunprotected(L, unroll, &status); 590 } 591 if (errorstatus(status)) { /* unrecoverable error? */ 592 L->status = cast_byte(status); /* mark thread as 'dead' */ 593 seterrorobj(L, status, L->top); /* push error message */ 594 L->ci->top = L->top; 595 } 596 else lua_assert(status == L->status); /* normal end or yield */ 597 } 598 L->nny = oldnny; /* restore 'nny' */ 599 L->nCcalls--; 600 lua_assert(L->nCcalls == ((from) ? from->nCcalls : 0)); 601 lua_unlock(L); 602 return status; 603 } 604 605 606 LUA_API int lua_isyieldable (lua_State *L) { 607 return (L->nny == 0); 608 } 609 610 611 LUA_API int lua_yieldk (lua_State *L, int nresults, lua_KContext ctx, 612 lua_KFunction k) { 613 CallInfo *ci = L->ci; 614 luai_userstateyield(L, nresults); 615 lua_lock(L); 616 api_checknelems(L, nresults); 617 if (L->nny > 0) { 618 if (L != G(L)->mainthread) 619 luaG_runerror(L, "attempt to yield across a C-call boundary"); 620 else 621 luaG_runerror(L, "attempt to yield from outside a coroutine"); 622 } 623 L->status = LUA_YIELD; 624 ci->extra = savestack(L, ci->func); /* save current 'func' */ 625 if (isLua(ci)) { /* inside a hook? */ 626 api_check(L, k == NULL, "hooks cannot continue after yielding"); 627 } 628 else { 629 if ((ci->u.c.k = k) != NULL) /* is there a continuation? */ 630 ci->u.c.ctx = ctx; /* save context */ 631 ci->func = L->top - nresults - 1; /* protect stack below results */ 632 luaD_throw(L, LUA_YIELD); 633 } 634 lua_assert(ci->callstatus & CIST_HOOKED); /* must be inside a hook */ 635 lua_unlock(L); 636 return 0; /* return to 'luaD_hook' */ 637 } 638 639 640 int luaD_pcall (lua_State *L, Pfunc func, void *u, 641 ptrdiff_t old_top, ptrdiff_t ef) { 642 int status; 643 CallInfo *old_ci = L->ci; 644 lu_byte old_allowhooks = L->allowhook; 645 unsigned short old_nny = L->nny; 646 ptrdiff_t old_errfunc = L->errfunc; 647 L->errfunc = ef; 648 status = luaD_rawrunprotected(L, func, u); 649 if (status != LUA_OK) { /* an error occurred? */ 650 StkId oldtop = restorestack(L, old_top); 651 luaF_close(L, oldtop); /* close possible pending closures */ 652 seterrorobj(L, status, oldtop); 653 L->ci = old_ci; 654 L->allowhook = old_allowhooks; 655 L->nny = old_nny; 656 luaD_shrinkstack(L); 657 } 658 L->errfunc = old_errfunc; 659 return status; 660 } 661 662 663 664 /* 665 ** Execute a protected parser. 666 */ 667 struct SParser { /* data to 'f_parser' */ 668 ZIO *z; 669 Mbuffer buff; /* dynamic structure used by the scanner */ 670 Dyndata dyd; /* dynamic structures used by the parser */ 671 const char *mode; 672 const char *name; 673 }; 674 675 676 static void checkmode (lua_State *L, const char *mode, const char *x) { 677 if (mode && strchr(mode, x[0]) == NULL) { 678 luaO_pushfstring(L, 679 "attempt to load a %s chunk (mode is '%s')", x, mode); 680 luaD_throw(L, LUA_ERRSYNTAX); 681 } 682 } 683 684 685 static void f_parser (lua_State *L, void *ud) { 686 LClosure *cl; 687 struct SParser *p = cast(struct SParser *, ud); 688 int c = zgetc(p->z); /* read first character */ 689 if (c == LUA_SIGNATURE[0]) { 690 checkmode(L, p->mode, "binary"); 691 cl = luaU_undump(L, p->z, &p->buff, p->name); 692 } 693 else { 694 checkmode(L, p->mode, "text"); 695 cl = luaY_parser(L, p->z, &p->buff, &p->dyd, p->name, c); 696 } 697 lua_assert(cl->nupvalues == cl->p->sizeupvalues); 698 luaF_initupvals(L, cl); 699 } 700 701 702 int luaD_protectedparser (lua_State *L, ZIO *z, const char *name, 703 const char *mode) { 704 struct SParser p; 705 int status; 706 L->nny++; /* cannot yield during parsing */ 707 p.z = z; p.name = name; p.mode = mode; 708 p.dyd.actvar.arr = NULL; p.dyd.actvar.size = 0; 709 p.dyd.gt.arr = NULL; p.dyd.gt.size = 0; 710 p.dyd.label.arr = NULL; p.dyd.label.size = 0; 711 luaZ_initbuffer(L, &p.buff); 712 status = luaD_pcall(L, f_parser, &p, savestack(L, L->top), L->errfunc); 713 luaZ_freebuffer(L, &p.buff); 714 luaM_freearray(L, p.dyd.actvar.arr, p.dyd.actvar.size); 715 luaM_freearray(L, p.dyd.gt.arr, p.dyd.gt.size); 716 luaM_freearray(L, p.dyd.label.arr, p.dyd.label.size); 717 L->nny--; 718 return status; 719 } 720 721 722