ldo.c

   1 /*
   2 ** $Id: ldo.c,v 2.38.1.3 2008/01/18 22:31:22 roberto Exp $
   3 ** Stack and Call structure of Lua
   4 ** See Copyright Notice in lua.h
   5 */
   6
   7 #if 0
   8 #include <setjmp.h>
   9 #include <stdlib.h>
  10 #include <string.h>
  11 #endif
  12
  13 #define ldo_c
  14 #define LUA_CORE
  15
  16 #include "lua.h"
  17
  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 /* chain list of long jump buffers */
  45 struct lua_longjmp {
  46   struct lua_longjmp *previous;
  47   luai_jmpbuf b;
  48   volatile int status;  /* error code */
  49 };
  50
  51
  52 void luaD_seterrorobj (lua_State *L, int errcode, StkId oldtop) {
  53   switch (errcode) {
  54     case LUA_ERRMEM: {
  55       setsvalue2s(L, oldtop, luaS_newliteral(L, MEMERRMSG));
  56       break;
  57     }
  58     case LUA_ERRERR: {
  59       setsvalue2s(L, oldtop, luaS_newliteral(L, "error in error handling"));
  60       break;
  61     }
  62     case LUA_ERRSYNTAX:
  63     case LUA_ERRRUN: {
  64       setobjs2s(L, oldtop, L->top - 1);  /* error message on current top */
  65       break;
  66     }
  67   }
  68   L->top = oldtop + 1;
  69 }
  70
  71
  72 static void restore_stack_limit (lua_State *L) {
  73   lua_assert(L->stack_last - L->stack == L->stacksize - EXTRA_STACK - 1);
  74   if (L->size_ci > LUAI_MAXCALLS) {  /* there was an overflow? */
  75     int inuse = cast_int(L->ci - L->base_ci);
  76     if (inuse + 1 < LUAI_MAXCALLS)  /* can `undo' overflow? */
  77       luaD_reallocCI(L, LUAI_MAXCALLS);
  78   }
  79 }
  80
  81
  82 static void resetstack (lua_State *L, int status) {
  83   L->ci = L->base_ci;
  84   L->base = L->ci->base;
  85   luaF_close(L, L->base);  /* close eventual pending closures */
  86   luaD_seterrorobj(L, status, L->base);
  87   L->nCcalls = L->baseCcalls;
  88   L->allowhook = 1;
  89   restore_stack_limit(L);
  90   L->errfunc = 0;
  91   L->errorJmp = NULL;
  92 }
  93
  94
  95 void luaD_throw (lua_State *L, int errcode) {
  96   if (L->errorJmp) {
  97     L->errorJmp->status = errcode;
  98     LUAI_THROW(L, L->errorJmp);
  99   }
 100   else {
 101     L->status = cast_byte(errcode);
 102     if (G(L)->panic) {
 103       resetstack(L, errcode);
 104       lua_unlock(L);
 105       G(L)->panic(L);
 106     }
 107     exit(EXIT_FAILURE);
 108   }
 109 }
 110
 111
 112 int luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud) {
 113   struct lua_longjmp lj;
 114   lj.status = 0;
 115   lj.previous = L->errorJmp;  /* chain new error handler */
 116   L->errorJmp = &lj;
 117   LUAI_TRY(L, &lj,
 118     (*f)(L, ud);
 119   );
 120   L->errorJmp = lj.previous;  /* restore old error handler */
 121   return lj.status;
 122 }
 123
 124 /* }====================================================== */
 125
 126
 127 static void correctstack (lua_State *L, TValue *oldstack) {
 128   CallInfo *ci;
 129   GCObject *up;
 130   L->top = (L->top - oldstack) + L->stack;
 131   for (up = L->openupval; up != NULL; up = up->gch.next)
 132     gco2uv(up)->v = (gco2uv(up)->v - oldstack) + L->stack;
 133   for (ci = L->base_ci; ci <= L->ci; ci++) {
 134     ci->top = (ci->top - oldstack) + L->stack;
 135     ci->base = (ci->base - oldstack) + L->stack;
 136     ci->func = (ci->func - oldstack) + L->stack;
 137   }
 138   L->base = (L->base - oldstack) + L->stack;
 139 }
 140
 141
 142 void luaD_reallocstack (lua_State *L, int newsize) {
 143   TValue *oldstack = L->stack;
 144   int realsize = newsize + 1 + EXTRA_STACK;
 145   lua_assert(L->stack_last - L->stack == L->stacksize - EXTRA_STACK - 1);
 146   luaM_reallocvector(L, L->stack, L->stacksize, realsize, TValue);
 147   L->stacksize = realsize;
 148   L->stack_last = L->stack+newsize;
 149   correctstack(L, oldstack);
 150 }
 151
 152
 153 void luaD_reallocCI (lua_State *L, int newsize) {
 154   CallInfo *oldci = L->base_ci;
 155   luaM_reallocvector(L, L->base_ci, L->size_ci, newsize, CallInfo);
 156   L->size_ci = newsize;
 157   L->ci = (L->ci - oldci) + L->base_ci;
 158   L->end_ci = L->base_ci + L->size_ci - 1;
 159 }
 160
 161
 162 void luaD_growstack (lua_State *L, int n) {
 163   if (n <= L->stacksize)  /* double size is enough? */
 164     luaD_reallocstack(L, 2*L->stacksize);
 165   else
 166     luaD_reallocstack(L, L->stacksize + n);
 167 }
 168
 169
 170 static CallInfo *growCI (lua_State *L) {
 171   if (L->size_ci > LUAI_MAXCALLS)  /* overflow while handling overflow? */
 172     luaD_throw(L, LUA_ERRERR);
 173   else {
 174     luaD_reallocCI(L, 2*L->size_ci);
 175     if (L->size_ci > LUAI_MAXCALLS)
 176       luaG_runerror(L, "stack overflow");
 177   }
 178   return ++L->ci;
 179 }
 180
 181
 182 void luaD_callhook (lua_State *L, int event, int line) {
 183   lua_Hook hook = L->hook;
 184   if (hook && L->allowhook) {
 185     ptrdiff_t top = savestack(L, L->top);
 186     ptrdiff_t ci_top = savestack(L, L->ci->top);
 187     lua_Debug ar;
 188     ar.event = event;
 189     ar.currentline = line;
 190     if (event == LUA_HOOKTAILRET)
 191       ar.i_ci = 0;  /* tail call; no debug information about it */
 192     else
 193       ar.i_ci = cast_int(L->ci - L->base_ci);
 194     luaD_checkstack(L, LUA_MINSTACK);  /* ensure minimum stack size */
 195     L->ci->top = L->top + LUA_MINSTACK;
 196     lua_assert(L->ci->top <= L->stack_last);
 197     L->allowhook = 0;  /* cannot call hooks inside a hook */
 198     lua_unlock(L);
 199     (*hook)(L, &ar);
 200     lua_lock(L);
 201     lua_assert(!L->allowhook);
 202     L->allowhook = 1;
 203     L->ci->top = restorestack(L, ci_top);
 204     L->top = restorestack(L, top);
 205   }
 206 }
 207
 208
 209 static StkId adjust_varargs (lua_State *L, Proto *p, int actual) {
 210   int i;
 211   int nfixargs = p->numparams;
 212   Table *htab = NULL;
 213   StkId base, fixed;
 214   for (; actual < nfixargs; ++actual)
 215     setnilvalue(L->top++);
 216 #if defined(LUA_COMPAT_VARARG)
 217   if (p->is_vararg & VARARG_NEEDSARG) { /* compat. with old-style vararg? */
 218     int nvar = actual - nfixargs;  /* number of extra arguments */
 219     lua_assert(p->is_vararg & VARARG_HASARG);
 220     luaC_checkGC(L);
 221     htab = luaH_new(L, nvar, 1);  /* create `arg' table */
 222     for (i=0; i<nvar; i++)  /* put extra arguments into `arg' table */
 223       setobj2n(L, luaH_setnum(L, htab, i+1), L->top - nvar + i);
 224     /* store counter in field `n' */
 225     setnvalue(luaH_setstr(L, htab, luaS_newliteral(L, "n")), cast_num(nvar));
 226   }
 227 #endif
 228   /* move fixed parameters to final position */
 229   fixed = L->top - actual;  /* first fixed argument */
 230   base = L->top;  /* final position of first argument */
 231   for (i=0; i<nfixargs; i++) {
 232     setobjs2s(L, L->top++, fixed+i);
 233     setnilvalue(fixed+i);
 234   }
 235   /* add `arg' parameter */
 236   if (htab) {
 237     sethvalue(L, L->top++, htab);
 238     lua_assert(iswhite(obj2gco(htab)));
 239   }
 240   return base;
 241 }
 242
 243
 244 static StkId tryfuncTM (lua_State *L, StkId func) {
 245   const TValue *tm = luaT_gettmbyobj(L, func, TM_CALL);
 246   StkId p;
 247   ptrdiff_t funcr = savestack(L, func);
 248   if (!ttisfunction(tm))
 249     luaG_typeerror(L, func, "call");
 250   /* Open a hole inside the stack at `func' */
 251   for (p = L->top; p > func; p--) setobjs2s(L, p, p-1);
 252   incr_top(L);
 253   func = restorestack(L, funcr);  /* previous call may change stack */
 254   setobj2s(L, func, tm);  /* tag method is the new function to be called */
 255   return func;
 256 }
 257
 258
 259
 260 #define inc_ci(L) \
 261   ((L->ci == L->end_ci) ? growCI(L) : \
 262    (condhardstacktests(luaD_reallocCI(L, L->size_ci)), ++L->ci))
 263
 264
 265 int luaD_precall (lua_State *L, StkId func, int nresults) {
 266   LClosure *cl;
 267   ptrdiff_t funcr;
 268   if (!ttisfunction(func)) /* `func' is not a function? */
 269     func = tryfuncTM(L, func);  /* check the `function' tag method */
 270   funcr = savestack(L, func);
 271   cl = &clvalue(func)->l;
 272   L->ci->savedpc = L->savedpc;
 273   if (!cl->isC) {  /* Lua function? prepare its call */
 274     CallInfo *ci;
 275     StkId st, base;
 276     Proto *p = cl->p;
 277     luaD_checkstack(L, p->maxstacksize);
 278     func = restorestack(L, funcr);
 279     if (!p->is_vararg) {  /* no varargs? */
 280       base = func + 1;
 281       if (L->top > base + p->numparams)
 282         L->top = base + p->numparams;
 283     }
 284     else {  /* vararg function */
 285       int nargs = cast_int(L->top - func) - 1;
 286       base = adjust_varargs(L, p, nargs);
 287       func = restorestack(L, funcr);  /* previous call may change the stack */
 288     }
 289     ci = inc_ci(L);  /* now `enter' new function */
 290     ci->func = func;
 291     L->base = ci->base = base;
 292     ci->top = L->base + p->maxstacksize;
 293     lua_assert(ci->top <= L->stack_last);
 294     L->savedpc = p->code;  /* starting point */
 295     ci->tailcalls = 0;
 296     ci->nresults = nresults;
 297     for (st = L->top; st < ci->top; st++)
 298       setnilvalue(st);
 299     L->top = ci->top;
 300     if (L->hookmask & LUA_MASKCALL) {
 301       L->savedpc++;  /* hooks assume 'pc' is already incremented */
 302       luaD_callhook(L, LUA_HOOKCALL, -1);
 303       L->savedpc--;  /* correct 'pc' */
 304     }
 305     return PCRLUA;
 306   }
 307   else {  /* if is a C function, call it */
 308     CallInfo *ci;
 309     int n;
 310     luaD_checkstack(L, LUA_MINSTACK);  /* ensure minimum stack size */
 311     ci = inc_ci(L);  /* now `enter' new function */
 312     ci->func = restorestack(L, funcr);
 313     L->base = ci->base = ci->func + 1;
 314     ci->top = L->top + LUA_MINSTACK;
 315     lua_assert(ci->top <= L->stack_last);
 316     ci->nresults = nresults;
 317     if (L->hookmask & LUA_MASKCALL)
 318       luaD_callhook(L, LUA_HOOKCALL, -1);
 319     lua_unlock(L);
 320     n = (*curr_func(L)->c.f)(L);  /* do the actual call */
 321     lua_lock(L);
 322     if (n < 0)  /* yielding? */
 323       return PCRYIELD;
 324     else {
 325       luaD_poscall(L, L->top - n);
 326       return PCRC;
 327     }
 328   }
 329 }
 330
 331
 332 static StkId callrethooks (lua_State *L, StkId firstResult) {
 333   ptrdiff_t fr = savestack(L, firstResult);  /* next call may change stack */
 334   luaD_callhook(L, LUA_HOOKRET, -1);
 335   if (f_isLua(L->ci)) {  /* Lua function? */
 336     while ((L->hookmask & LUA_MASKRET) && L->ci->tailcalls--) /* tail calls */
 337       luaD_callhook(L, LUA_HOOKTAILRET, -1);
 338   }
 339   return restorestack(L, fr);
 340 }
 341
 342
 343 int luaD_poscall (lua_State *L, StkId firstResult) {
 344   StkId res;
 345   int wanted, i;
 346   CallInfo *ci;
 347   if (L->hookmask & LUA_MASKRET)
 348     firstResult = callrethooks(L, firstResult);
 349   ci = L->ci--;
 350   res = ci->func;  /* res == final position of 1st result */
 351   wanted = ci->nresults;
 352   L->base = (ci - 1)->base;  /* restore base */
 353   L->savedpc = (ci - 1)->savedpc;  /* restore savedpc */
 354   /* move results to correct place */
 355   for (i = wanted; i != 0 && firstResult < L->top; i--)
 356     setobjs2s(L, res++, firstResult++);
 357   while (i-- > 0)
 358     setnilvalue(res++);
 359   L->top = res;
 360   return (wanted - LUA_MULTRET);  /* 0 iff wanted == LUA_MULTRET */
 361 }
 362
 363
 364 /*
 365 ** Call a function (C or Lua). The function to be called is at *func.
 366 ** The arguments are on the stack, right after the function.
 367 ** When returns, all the results are on the stack, starting at the original
 368 ** function position.
 369 */
 370 void luaD_call (lua_State *L, StkId func, int nResults) {
 371   if (++L->nCcalls >= LUAI_MAXCCALLS) {
 372     if (L->nCcalls == LUAI_MAXCCALLS)
 373       luaG_runerror(L, "C stack overflow");
 374     else if (L->nCcalls >= (LUAI_MAXCCALLS + (LUAI_MAXCCALLS>>3)))
 375       luaD_throw(L, LUA_ERRERR);  /* error while handing stack error */
 376   }
 377   if (luaD_precall(L, func, nResults) == PCRLUA)  /* is a Lua function? */
 378     luaV_execute(L, 1);  /* call it */
 379   L->nCcalls--;
 380   luaC_checkGC(L);
 381 }
 382
 383
 384 static void resume (lua_State *L, void *ud) {
 385   StkId firstArg = cast(StkId, ud);
 386   CallInfo *ci = L->ci;
 387   if (L->status == 0) {  /* start coroutine? */
 388     lua_assert(ci == L->base_ci && firstArg > L->base);
 389     if (luaD_precall(L, firstArg - 1, LUA_MULTRET) != PCRLUA)
 390       return;
 391   }
 392   else {  /* resuming from previous yield */
 393     lua_assert(L->status == LUA_YIELD);
 394     L->status = 0;
 395     if (!f_isLua(ci)) {  /* `common' yield? */
 396       /* finish interrupted execution of `OP_CALL' */
 397       lua_assert(GET_OPCODE(*((ci-1)->savedpc - 1)) == OP_CALL ||
 398                  GET_OPCODE(*((ci-1)->savedpc - 1)) == OP_TAILCALL);
 399       if (luaD_poscall(L, firstArg))  /* complete it... */
 400         L->top = L->ci->top;  /* and correct top if not multiple results */
 401     }
 402     else  /* yielded inside a hook: just continue its execution */
 403       L->base = L->ci->base;
 404   }
 405   luaV_execute(L, cast_int(L->ci - L->base_ci));
 406 }
 407
 408
 409 static int resume_error (lua_State *L, const char *msg) {
 410   L->top = L->ci->base;
 411   setsvalue2s(L, L->top, luaS_new(L, msg));
 412   incr_top(L);
 413   lua_unlock(L);
 414   return LUA_ERRRUN;
 415 }
 416
 417
 418 LUA_API int lua_resume (lua_State *L, int nargs) {
 419   int status;
 420   lua_lock(L);
 421   if (L->status != LUA_YIELD && (L->status != 0 || L->ci != L->base_ci))
 422       return resume_error(L, "cannot resume non-suspended coroutine");
 423   if (L->nCcalls >= LUAI_MAXCCALLS)
 424     return resume_error(L, "C stack overflow");
 425   luai_userstateresume(L, nargs);
 426   lua_assert(L->errfunc == 0);
 427   L->baseCcalls = ++L->nCcalls;
 428   status = luaD_rawrunprotected(L, resume, L->top - nargs);
 429   if (status != 0) {  /* error? */
 430     L->status = cast_byte(status);  /* mark thread as `dead' */
 431     luaD_seterrorobj(L, status, L->top);
 432     L->ci->top = L->top;
 433   }
 434   else {
 435     lua_assert(L->nCcalls == L->baseCcalls);
 436     status = L->status;
 437   }
 438   --L->nCcalls;
 439   lua_unlock(L);
 440   return status;
 441 }
 442
 443
 444 LUA_API int lua_yield (lua_State *L, int nresults) {
 445   luai_userstateyield(L, nresults);
 446   lua_lock(L);
 447   if (L->nCcalls > L->baseCcalls)
 448     luaG_runerror(L, "attempt to yield across metamethod/C-call boundary");
 449   L->base = L->top - nresults;  /* protect stack slots below */
 450   L->status = LUA_YIELD;
 451   lua_unlock(L);
 452   return -1;
 453 }
 454
 455
 456 int luaD_pcall (lua_State *L, Pfunc func, void *u,
 457                 ptrdiff_t old_top, ptrdiff_t ef) {
 458   int status;
 459   unsigned short oldnCcalls = L->nCcalls;
 460   ptrdiff_t old_ci = saveci(L, L->ci);
 461   lu_byte old_allowhooks = L->allowhook;
 462   ptrdiff_t old_errfunc = L->errfunc;
 463   L->errfunc = ef;
 464   status = luaD_rawrunprotected(L, func, u);
 465   if (status != 0) {  /* an error occurred? */
 466     StkId oldtop = restorestack(L, old_top);
 467     luaF_close(L, oldtop);  /* close eventual pending closures */
 468     luaD_seterrorobj(L, status, oldtop);
 469     L->nCcalls = oldnCcalls;
 470     L->ci = restoreci(L, old_ci);
 471     L->base = L->ci->base;
 472     L->savedpc = L->ci->savedpc;
 473     L->allowhook = old_allowhooks;
 474     restore_stack_limit(L);
 475   }
 476   L->errfunc = old_errfunc;
 477   return status;
 478 }
 479
 480
 481
 482 /*
 483 ** Execute a protected parser.
 484 */
 485 struct SParser {  /* data to `f_parser' */
 486   ZIO *z;
 487   Mbuffer buff;  /* buffer to be used by the scanner */
 488   const char *name;
 489 };
 490
 491 static void f_parser (lua_State *L, void *ud) {
 492   int i;
 493   Proto *tf;
 494   Closure *cl;
 495   struct SParser *p = cast(struct SParser *, ud);
 496   int c = luaZ_lookahead(p->z);
 497   luaC_checkGC(L);
 498   tf = ((c == LUA_SIGNATURE[0]) ? luaU_undump : luaY_parser)(L, p->z,
 499                                                              &p->buff, p->name);
 500   cl = luaF_newLclosure(L, tf->nups, hvalue(gt(L)));
 501   cl->l.p = tf;
 502   for (i = 0; i < tf->nups; i++)  /* initialize eventual upvalues */
 503     cl->l.upvals[i] = luaF_newupval(L);
 504   setclvalue(L, L->top, cl);
 505   incr_top(L);
 506 }
 507
 508
 509 int luaD_protectedparser (lua_State *L, ZIO *z, const char *name) {
 510   struct SParser p;
 511   int status;
 512   p.z = z; p.name = name;
 513   luaZ_initbuffer(L, &p.buff);
 514   status = luaD_pcall(L, f_parser, &p, savestack(L, L->top), L->errfunc);
 515   luaZ_freebuffer(L, &p.buff);
 516   return status;
 517 }
 518
 519