1 /* $NetBSD: ldo.c,v 1.9 2018/08/04 17:30:01 alnsn Exp $ */ 2 3 /* 4 ** Id: ldo.c,v 2.157.1.1 2017/04/19 17:20:42 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 /* _KERNEL */ 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 /* 158 ** {================================================================== 159 ** Stack reallocation 160 ** =================================================================== 161 */ 162 static void correctstack (lua_State *L, TValue *oldstack) { 163 CallInfo *ci; 164 UpVal *up; 165 L->top = (L->top - oldstack) + L->stack; 166 for (up = L->openupval; up != NULL; up = up->u.open.next) 167 up->v = (up->v - oldstack) + L->stack; 168 for (ci = L->ci; ci != NULL; ci = ci->previous) { 169 ci->top = (ci->top - oldstack) + L->stack; 170 ci->func = (ci->func - oldstack) + L->stack; 171 if (isLua(ci)) 172 ci->u.l.base = (ci->u.l.base - oldstack) + L->stack; 173 } 174 } 175 176 177 /* some space for error handling */ 178 #define ERRORSTACKSIZE (LUAI_MAXSTACK + 200) 179 180 181 void luaD_reallocstack (lua_State *L, int newsize) { 182 TValue *oldstack = L->stack; 183 int lim = L->stacksize; 184 lua_assert(newsize <= LUAI_MAXSTACK || newsize == ERRORSTACKSIZE); 185 lua_assert(L->stack_last - L->stack == L->stacksize - EXTRA_STACK); 186 luaM_reallocvector(L, L->stack, L->stacksize, newsize, TValue); 187 for (; lim < newsize; lim++) 188 setnilvalue(L->stack + lim); /* erase new segment */ 189 L->stacksize = newsize; 190 L->stack_last = L->stack + newsize - EXTRA_STACK; 191 correctstack(L, oldstack); 192 } 193 194 195 void luaD_growstack (lua_State *L, int n) { 196 int size = L->stacksize; 197 if (size > LUAI_MAXSTACK) /* error after extra size? */ 198 luaD_throw(L, LUA_ERRERR); 199 else { 200 int needed = cast_int(L->top - L->stack) + n + EXTRA_STACK; 201 int newsize = 2 * size; 202 if (newsize > LUAI_MAXSTACK) newsize = LUAI_MAXSTACK; 203 if (newsize < needed) newsize = needed; 204 if (newsize > LUAI_MAXSTACK) { /* stack overflow? */ 205 luaD_reallocstack(L, ERRORSTACKSIZE); 206 luaG_runerror(L, "stack overflow"); 207 } 208 else 209 luaD_reallocstack(L, newsize); 210 } 211 } 212 213 214 static int stackinuse (lua_State *L) { 215 CallInfo *ci; 216 StkId lim = L->top; 217 for (ci = L->ci; ci != NULL; ci = ci->previous) { 218 if (lim < ci->top) lim = ci->top; 219 } 220 lua_assert(lim <= L->stack_last); 221 return cast_int(lim - L->stack) + 1; /* part of stack in use */ 222 } 223 224 225 void luaD_shrinkstack (lua_State *L) { 226 int inuse = stackinuse(L); 227 int goodsize = inuse + (inuse / 8) + 2*EXTRA_STACK; 228 if (goodsize > LUAI_MAXSTACK) 229 goodsize = LUAI_MAXSTACK; /* respect stack limit */ 230 if (L->stacksize > LUAI_MAXSTACK) /* had been handling stack overflow? */ 231 luaE_freeCI(L); /* free all CIs (list grew because of an error) */ 232 else 233 luaE_shrinkCI(L); /* shrink list */ 234 /* if thread is currently not handling a stack overflow and its 235 good size is smaller than current size, shrink its stack */ 236 if (inuse <= (LUAI_MAXSTACK - EXTRA_STACK) && 237 goodsize < L->stacksize) 238 luaD_reallocstack(L, goodsize); 239 else /* don't change stack */ 240 condmovestack(L,{},{}); /* (change only for debugging) */ 241 } 242 243 244 void luaD_inctop (lua_State *L) { 245 luaD_checkstack(L, 1); 246 L->top++; 247 } 248 249 /* }================================================================== */ 250 251 252 /* 253 ** Call a hook for the given event. Make sure there is a hook to be 254 ** called. (Both 'L->hook' and 'L->hookmask', which triggers this 255 ** function, can be changed asynchronously by signals.) 256 */ 257 void luaD_hook (lua_State *L, int event, int line) { 258 lua_Hook hook = L->hook; 259 if (hook && L->allowhook) { /* make sure there is a hook */ 260 CallInfo *ci = L->ci; 261 ptrdiff_t top = savestack(L, L->top); 262 ptrdiff_t ci_top = savestack(L, ci->top); 263 lua_Debug ar; 264 ar.event = event; 265 ar.currentline = line; 266 ar.i_ci = ci; 267 luaD_checkstack(L, LUA_MINSTACK); /* ensure minimum stack size */ 268 ci->top = L->top + LUA_MINSTACK; 269 lua_assert(ci->top <= L->stack_last); 270 L->allowhook = 0; /* cannot call hooks inside a hook */ 271 ci->callstatus |= CIST_HOOKED; 272 lua_unlock(L); 273 (*hook)(L, &ar); 274 lua_lock(L); 275 lua_assert(!L->allowhook); 276 L->allowhook = 1; 277 ci->top = restorestack(L, ci_top); 278 L->top = restorestack(L, top); 279 ci->callstatus &= ~CIST_HOOKED; 280 } 281 } 282 283 284 static void callhook (lua_State *L, CallInfo *ci) { 285 int hook = LUA_HOOKCALL; 286 ci->u.l.savedpc++; /* hooks assume 'pc' is already incremented */ 287 if (isLua(ci->previous) && 288 GET_OPCODE(*(ci->previous->u.l.savedpc - 1)) == OP_TAILCALL) { 289 ci->callstatus |= CIST_TAIL; 290 hook = LUA_HOOKTAILCALL; 291 } 292 luaD_hook(L, hook, -1); 293 ci->u.l.savedpc--; /* correct 'pc' */ 294 } 295 296 297 static StkId adjust_varargs (lua_State *L, Proto *p, int actual) { 298 int i; 299 int nfixargs = p->numparams; 300 StkId base, fixed; 301 /* move fixed parameters to final position */ 302 fixed = L->top - actual; /* first fixed argument */ 303 base = L->top; /* final position of first argument */ 304 for (i = 0; i < nfixargs && i < actual; i++) { 305 setobjs2s(L, L->top++, fixed + i); 306 setnilvalue(fixed + i); /* erase original copy (for GC) */ 307 } 308 for (; i < nfixargs; i++) 309 setnilvalue(L->top++); /* complete missing arguments */ 310 return base; 311 } 312 313 314 /* 315 ** Check whether __call metafield of 'func' is a function. If so, put 316 ** it in stack below original 'func' so that 'luaD_precall' can call 317 ** it. Raise an error if __call metafield is not a function. 318 */ 319 static void tryfuncTM (lua_State *L, StkId func) { 320 const TValue *tm = luaT_gettmbyobj(L, func, TM_CALL); 321 StkId p; 322 if (!ttisfunction(tm)) 323 luaG_typeerror(L, func, "call"); 324 /* Open a hole inside the stack at 'func' */ 325 for (p = L->top; p > func; p--) 326 setobjs2s(L, p, p-1); 327 L->top++; /* slot ensured by caller */ 328 setobj2s(L, func, tm); /* tag method is the new function to be called */ 329 } 330 331 332 /* 333 ** Given 'nres' results at 'firstResult', move 'wanted' of them to 'res'. 334 ** Handle most typical cases (zero results for commands, one result for 335 ** expressions, multiple results for tail calls/single parameters) 336 ** separated. 337 */ 338 static int moveresults (lua_State *L, const TValue *firstResult, StkId res, 339 int nres, int wanted) { 340 switch (wanted) { /* handle typical cases separately */ 341 case 0: break; /* nothing to move */ 342 case 1: { /* one result needed */ 343 if (nres == 0) /* no results? */ 344 firstResult = luaO_nilobject; /* adjust with nil */ 345 setobjs2s(L, res, firstResult); /* move it to proper place */ 346 break; 347 } 348 case LUA_MULTRET: { 349 int i; 350 for (i = 0; i < nres; i++) /* move all results to correct place */ 351 setobjs2s(L, res + i, firstResult + i); 352 L->top = res + nres; 353 return 0; /* wanted == LUA_MULTRET */ 354 } 355 default: { 356 int i; 357 if (wanted <= nres) { /* enough results? */ 358 for (i = 0; i < wanted; i++) /* move wanted results to correct place */ 359 setobjs2s(L, res + i, firstResult + i); 360 } 361 else { /* not enough results; use all of them plus nils */ 362 for (i = 0; i < nres; i++) /* move all results to correct place */ 363 setobjs2s(L, res + i, firstResult + i); 364 for (; i < wanted; i++) /* complete wanted number of results */ 365 setnilvalue(res + i); 366 } 367 break; 368 } 369 } 370 L->top = res + wanted; /* top points after the last result */ 371 return 1; 372 } 373 374 375 /* 376 ** Finishes a function call: calls hook if necessary, removes CallInfo, 377 ** moves current number of results to proper place; returns 0 iff call 378 ** wanted multiple (variable number of) results. 379 */ 380 int luaD_poscall (lua_State *L, CallInfo *ci, StkId firstResult, int nres) { 381 StkId res; 382 int wanted = ci->nresults; 383 if (L->hookmask & (LUA_MASKRET | LUA_MASKLINE)) { 384 if (L->hookmask & LUA_MASKRET) { 385 ptrdiff_t fr = savestack(L, firstResult); /* hook may change stack */ 386 luaD_hook(L, LUA_HOOKRET, -1); 387 firstResult = restorestack(L, fr); 388 } 389 L->oldpc = ci->previous->u.l.savedpc; /* 'oldpc' for caller function */ 390 } 391 res = ci->func; /* res == final position of 1st result */ 392 L->ci = ci->previous; /* back to caller */ 393 /* move results to proper place */ 394 return moveresults(L, firstResult, res, nres, wanted); 395 } 396 397 398 399 #define next_ci(L) (L->ci = (L->ci->next ? L->ci->next : luaE_extendCI(L))) 400 401 402 /* macro to check stack size, preserving 'p' */ 403 #define checkstackp(L,n,p) \ 404 luaD_checkstackaux(L, n, \ 405 ptrdiff_t t__ = savestack(L, p); /* save 'p' */ \ 406 luaC_checkGC(L), /* stack grow uses memory */ \ 407 p = restorestack(L, t__)) /* 'pos' part: restore 'p' */ 408 409 410 /* 411 ** Prepares a function call: checks the stack, creates a new CallInfo 412 ** entry, fills in the relevant information, calls hook if needed. 413 ** If function is a C function, does the call, too. (Otherwise, leave 414 ** the execution ('luaV_execute') to the caller, to allow stackless 415 ** calls.) Returns true iff function has been executed (C function). 416 */ 417 int luaD_precall (lua_State *L, StkId func, int nresults) { 418 lua_CFunction f; 419 CallInfo *ci; 420 switch (ttype(func)) { 421 case LUA_TCCL: /* C closure */ 422 f = clCvalue(func)->f; 423 goto Cfunc; 424 case LUA_TLCF: /* light C function */ 425 f = fvalue(func); 426 Cfunc: { 427 int n; /* number of returns */ 428 checkstackp(L, LUA_MINSTACK, func); /* ensure minimum stack size */ 429 ci = next_ci(L); /* now 'enter' new function */ 430 ci->nresults = nresults; 431 ci->func = func; 432 ci->top = L->top + LUA_MINSTACK; 433 lua_assert(ci->top <= L->stack_last); 434 ci->callstatus = 0; 435 if (L->hookmask & LUA_MASKCALL) 436 luaD_hook(L, LUA_HOOKCALL, -1); 437 lua_unlock(L); 438 n = (*f)(L); /* do the actual call */ 439 lua_lock(L); 440 api_checknelems(L, n); 441 luaD_poscall(L, ci, L->top - n, n); 442 return 1; 443 } 444 case LUA_TLCL: { /* Lua function: prepare its call */ 445 StkId base; 446 Proto *p = clLvalue(func)->p; 447 int n = cast_int(L->top - func) - 1; /* number of real arguments */ 448 int fsize = p->maxstacksize; /* frame size */ 449 checkstackp(L, fsize, func); 450 if (p->is_vararg) 451 base = adjust_varargs(L, p, n); 452 else { /* non vararg function */ 453 for (; n < p->numparams; n++) 454 setnilvalue(L->top++); /* complete missing arguments */ 455 base = func + 1; 456 } 457 ci = next_ci(L); /* now 'enter' new function */ 458 ci->nresults = nresults; 459 ci->func = func; 460 ci->u.l.base = base; 461 L->top = ci->top = base + fsize; 462 lua_assert(ci->top <= L->stack_last); 463 ci->u.l.savedpc = p->code; /* starting point */ 464 ci->callstatus = CIST_LUA; 465 if (L->hookmask & LUA_MASKCALL) 466 callhook(L, ci); 467 return 0; 468 } 469 default: { /* not a function */ 470 checkstackp(L, 1, func); /* ensure space for metamethod */ 471 tryfuncTM(L, func); /* try to get '__call' metamethod */ 472 return luaD_precall(L, func, nresults); /* now it must be a function */ 473 } 474 } 475 } 476 477 478 /* 479 ** Check appropriate error for stack overflow ("regular" overflow or 480 ** overflow while handling stack overflow). If 'nCalls' is larger than 481 ** LUAI_MAXCCALLS (which means it is handling a "regular" overflow) but 482 ** smaller than 9/8 of LUAI_MAXCCALLS, does not report an error (to 483 ** allow overflow handling to work) 484 */ 485 static void stackerror (lua_State *L) { 486 if (L->nCcalls == LUAI_MAXCCALLS) 487 luaG_runerror(L, "C stack overflow"); 488 else if (L->nCcalls >= (LUAI_MAXCCALLS + (LUAI_MAXCCALLS>>3))) 489 luaD_throw(L, LUA_ERRERR); /* error while handing stack error */ 490 } 491 492 493 /* 494 ** Call a function (C or Lua). The function to be called is at *func. 495 ** The arguments are on the stack, right after the function. 496 ** When returns, all the results are on the stack, starting at the original 497 ** function position. 498 */ 499 void luaD_call (lua_State *L, StkId func, int nResults) { 500 if (++L->nCcalls >= LUAI_MAXCCALLS) 501 stackerror(L); 502 if (!luaD_precall(L, func, nResults)) /* is a Lua function? */ 503 luaV_execute(L); /* call it */ 504 L->nCcalls--; 505 } 506 507 508 /* 509 ** Similar to 'luaD_call', but does not allow yields during the call 510 */ 511 void luaD_callnoyield (lua_State *L, StkId func, int nResults) { 512 L->nny++; 513 luaD_call(L, func, nResults); 514 L->nny--; 515 } 516 517 518 /* 519 ** Completes the execution of an interrupted C function, calling its 520 ** continuation function. 521 */ 522 static void finishCcall (lua_State *L, int status) { 523 CallInfo *ci = L->ci; 524 int n; 525 /* must have a continuation and must be able to call it */ 526 lua_assert(ci->u.c.k != NULL && L->nny == 0); 527 /* error status can only happen in a protected call */ 528 lua_assert((ci->callstatus & CIST_YPCALL) || status == LUA_YIELD); 529 if (ci->callstatus & CIST_YPCALL) { /* was inside a pcall? */ 530 ci->callstatus &= ~CIST_YPCALL; /* continuation is also inside it */ 531 L->errfunc = ci->u.c.old_errfunc; /* with the same error function */ 532 } 533 /* finish 'lua_callk'/'lua_pcall'; CIST_YPCALL and 'errfunc' already 534 handled */ 535 adjustresults(L, ci->nresults); 536 lua_unlock(L); 537 n = (*ci->u.c.k)(L, status, ci->u.c.ctx); /* call continuation function */ 538 lua_lock(L); 539 api_checknelems(L, n); 540 luaD_poscall(L, ci, L->top - n, n); /* finish 'luaD_precall' */ 541 } 542 543 544 /* 545 ** Executes "full continuation" (everything in the stack) of a 546 ** previously interrupted coroutine until the stack is empty (or another 547 ** interruption long-jumps out of the loop). If the coroutine is 548 ** recovering from an error, 'ud' points to the error status, which must 549 ** be passed to the first continuation function (otherwise the default 550 ** status is LUA_YIELD). 551 */ 552 static void unroll (lua_State *L, void *ud) { 553 if (ud != NULL) /* error status? */ 554 finishCcall(L, *(int *)ud); /* finish 'lua_pcallk' callee */ 555 while (L->ci != &L->base_ci) { /* something in the stack */ 556 if (!isLua(L->ci)) /* C function? */ 557 finishCcall(L, LUA_YIELD); /* complete its execution */ 558 else { /* Lua function */ 559 luaV_finishOp(L); /* finish interrupted instruction */ 560 luaV_execute(L); /* execute down to higher C 'boundary' */ 561 } 562 } 563 } 564 565 566 /* 567 ** Try to find a suspended protected call (a "recover point") for the 568 ** given thread. 569 */ 570 static CallInfo *findpcall (lua_State *L) { 571 CallInfo *ci; 572 for (ci = L->ci; ci != NULL; ci = ci->previous) { /* search for a pcall */ 573 if (ci->callstatus & CIST_YPCALL) 574 return ci; 575 } 576 return NULL; /* no pending pcall */ 577 } 578 579 580 /* 581 ** Recovers from an error in a coroutine. Finds a recover point (if 582 ** there is one) and completes the execution of the interrupted 583 ** 'luaD_pcall'. If there is no recover point, returns zero. 584 */ 585 static int recover (lua_State *L, int status) { 586 StkId oldtop; 587 CallInfo *ci = findpcall(L); 588 if (ci == NULL) return 0; /* no recovery point */ 589 /* "finish" luaD_pcall */ 590 oldtop = restorestack(L, ci->extra); 591 luaF_close(L, oldtop); 592 seterrorobj(L, status, oldtop); 593 L->ci = ci; 594 L->allowhook = getoah(ci->callstatus); /* restore original 'allowhook' */ 595 L->nny = 0; /* should be zero to be yieldable */ 596 luaD_shrinkstack(L); 597 L->errfunc = ci->u.c.old_errfunc; 598 return 1; /* continue running the coroutine */ 599 } 600 601 602 /* 603 ** Signal an error in the call to 'lua_resume', not in the execution 604 ** of the coroutine itself. (Such errors should not be handled by any 605 ** coroutine error handler and should not kill the coroutine.) 606 */ 607 static int resume_error (lua_State *L, const char *msg, int narg) { 608 L->top -= narg; /* remove args from the stack */ 609 setsvalue2s(L, L->top, luaS_new(L, msg)); /* push error message */ 610 api_incr_top(L); 611 lua_unlock(L); 612 return LUA_ERRRUN; 613 } 614 615 616 /* 617 ** Do the work for 'lua_resume' in protected mode. Most of the work 618 ** depends on the status of the coroutine: initial state, suspended 619 ** inside a hook, or regularly suspended (optionally with a continuation 620 ** function), plus erroneous cases: non-suspended coroutine or dead 621 ** coroutine. 622 */ 623 static void resume (lua_State *L, void *ud) { 624 int n = *(cast(int*, ud)); /* number of arguments */ 625 StkId firstArg = L->top - n; /* first argument */ 626 CallInfo *ci = L->ci; 627 if (L->status == LUA_OK) { /* starting a coroutine? */ 628 if (!luaD_precall(L, firstArg - 1, LUA_MULTRET)) /* Lua function? */ 629 luaV_execute(L); /* call it */ 630 } 631 else { /* resuming from previous yield */ 632 lua_assert(L->status == LUA_YIELD); 633 L->status = LUA_OK; /* mark that it is running (again) */ 634 ci->func = restorestack(L, ci->extra); 635 if (isLua(ci)) /* yielded inside a hook? */ 636 luaV_execute(L); /* just continue running Lua code */ 637 else { /* 'common' yield */ 638 if (ci->u.c.k != NULL) { /* does it have a continuation function? */ 639 lua_unlock(L); 640 n = (*ci->u.c.k)(L, LUA_YIELD, ci->u.c.ctx); /* call continuation */ 641 lua_lock(L); 642 api_checknelems(L, n); 643 firstArg = L->top - n; /* yield results come from continuation */ 644 } 645 luaD_poscall(L, ci, firstArg, n); /* finish 'luaD_precall' */ 646 } 647 unroll(L, NULL); /* run continuation */ 648 } 649 } 650 651 652 LUA_API int lua_resume (lua_State *L, lua_State *from, int nargs) { 653 int status; 654 unsigned short oldnny = L->nny; /* save "number of non-yieldable" calls */ 655 lua_lock(L); 656 if (L->status == LUA_OK) { /* may be starting a coroutine */ 657 if (L->ci != &L->base_ci) /* not in base level? */ 658 return resume_error(L, "cannot resume non-suspended coroutine", nargs); 659 } 660 else if (L->status != LUA_YIELD) 661 return resume_error(L, "cannot resume dead coroutine", nargs); 662 L->nCcalls = (from) ? from->nCcalls + 1 : 1; 663 if (L->nCcalls >= LUAI_MAXCCALLS) 664 return resume_error(L, "C stack overflow", nargs); 665 luai_userstateresume(L, nargs); 666 L->nny = 0; /* allow yields */ 667 api_checknelems(L, (L->status == LUA_OK) ? nargs + 1 : nargs); 668 status = luaD_rawrunprotected(L, resume, &nargs); 669 if (status == -1) /* error calling 'lua_resume'? */ 670 status = LUA_ERRRUN; 671 else { /* continue running after recoverable errors */ 672 while (errorstatus(status) && recover(L, status)) { 673 /* unroll continuation */ 674 status = luaD_rawrunprotected(L, unroll, &status); 675 } 676 if (errorstatus(status)) { /* unrecoverable error? */ 677 L->status = cast_byte(status); /* mark thread as 'dead' */ 678 seterrorobj(L, status, L->top); /* push error message */ 679 L->ci->top = L->top; 680 } 681 else lua_assert(status == L->status); /* normal end or yield */ 682 } 683 L->nny = oldnny; /* restore 'nny' */ 684 L->nCcalls--; 685 lua_assert(L->nCcalls == ((from) ? from->nCcalls : 0)); 686 lua_unlock(L); 687 return status; 688 } 689 690 691 LUA_API int lua_isyieldable (lua_State *L) { 692 return (L->nny == 0); 693 } 694 695 696 LUA_API int lua_yieldk (lua_State *L, int nresults, lua_KContext ctx, 697 lua_KFunction k) { 698 CallInfo *ci = L->ci; 699 luai_userstateyield(L, nresults); 700 lua_lock(L); 701 api_checknelems(L, nresults); 702 if (L->nny > 0) { 703 if (L != G(L)->mainthread) 704 luaG_runerror(L, "attempt to yield across a C-call boundary"); 705 else 706 luaG_runerror(L, "attempt to yield from outside a coroutine"); 707 } 708 L->status = LUA_YIELD; 709 ci->extra = savestack(L, ci->func); /* save current 'func' */ 710 if (isLua(ci)) { /* inside a hook? */ 711 api_check(L, k == NULL, "hooks cannot continue after yielding"); 712 } 713 else { 714 if ((ci->u.c.k = k) != NULL) /* is there a continuation? */ 715 ci->u.c.ctx = ctx; /* save context */ 716 ci->func = L->top - nresults - 1; /* protect stack below results */ 717 luaD_throw(L, LUA_YIELD); 718 } 719 lua_assert(ci->callstatus & CIST_HOOKED); /* must be inside a hook */ 720 lua_unlock(L); 721 return 0; /* return to 'luaD_hook' */ 722 } 723 724 725 int luaD_pcall (lua_State *L, Pfunc func, void *u, 726 ptrdiff_t old_top, ptrdiff_t ef) { 727 int status; 728 CallInfo *old_ci = L->ci; 729 lu_byte old_allowhooks = L->allowhook; 730 unsigned short old_nny = L->nny; 731 ptrdiff_t old_errfunc = L->errfunc; 732 L->errfunc = ef; 733 status = luaD_rawrunprotected(L, func, u); 734 if (status != LUA_OK) { /* an error occurred? */ 735 StkId oldtop = restorestack(L, old_top); 736 luaF_close(L, oldtop); /* close possible pending closures */ 737 seterrorobj(L, status, oldtop); 738 L->ci = old_ci; 739 L->allowhook = old_allowhooks; 740 L->nny = old_nny; 741 luaD_shrinkstack(L); 742 } 743 L->errfunc = old_errfunc; 744 return status; 745 } 746 747 748 749 /* 750 ** Execute a protected parser. 751 */ 752 struct SParser { /* data to 'f_parser' */ 753 ZIO *z; 754 Mbuffer buff; /* dynamic structure used by the scanner */ 755 Dyndata dyd; /* dynamic structures used by the parser */ 756 const char *mode; 757 const char *name; 758 }; 759 760 761 static void checkmode (lua_State *L, const char *mode, const char *x) { 762 if (mode && strchr(mode, x[0]) == NULL) { 763 luaO_pushfstring(L, 764 "attempt to load a %s chunk (mode is '%s')", x, mode); 765 luaD_throw(L, LUA_ERRSYNTAX); 766 } 767 } 768 769 770 static void f_parser (lua_State *L, void *ud) { 771 LClosure *cl; 772 struct SParser *p = cast(struct SParser *, ud); 773 int c = zgetc(p->z); /* read first character */ 774 if (c == LUA_SIGNATURE[0]) { 775 checkmode(L, p->mode, "binary"); 776 cl = luaU_undump(L, p->z, p->name); 777 } 778 else { 779 checkmode(L, p->mode, "text"); 780 cl = luaY_parser(L, p->z, &p->buff, &p->dyd, p->name, c); 781 } 782 lua_assert(cl->nupvalues == cl->p->sizeupvalues); 783 luaF_initupvals(L, cl); 784 } 785 786 787 int luaD_protectedparser (lua_State *L, ZIO *z, const char *name, 788 const char *mode) { 789 struct SParser p; 790 int status; 791 L->nny++; /* cannot yield during parsing */ 792 p.z = z; p.name = name; p.mode = mode; 793 p.dyd.actvar.arr = NULL; p.dyd.actvar.size = 0; 794 p.dyd.gt.arr = NULL; p.dyd.gt.size = 0; 795 p.dyd.label.arr = NULL; p.dyd.label.size = 0; 796 luaZ_initbuffer(L, &p.buff); 797 status = luaD_pcall(L, f_parser, &p, savestack(L, L->top), L->errfunc); 798 luaZ_freebuffer(L, &p.buff); 799 luaM_freearray(L, p.dyd.actvar.arr, p.dyd.actvar.size); 800 luaM_freearray(L, p.dyd.gt.arr, p.dyd.gt.size); 801 luaM_freearray(L, p.dyd.label.arr, p.dyd.label.size); 802 L->nny--; 803 return status; 804 } 805 806 807