external/mit/lua/dist/src/ldo.c

   1 /*      $NetBSD: ldo.c,v 1.1.1.2 2012/03/15 00:08:09 alnsn Exp $        */
   2
   3 /*
   4 ** $Id: ldo.c,v 1.1.1.2 2012/03/15 00:08:09 alnsn Exp $
   5 ** Stack and Call structure of Lua
   6 ** See Copyright Notice in lua.h
   7 */
   8
   9
  10 #include <setjmp.h>
  11 #include <stdlib.h>
  12 #include <string.h>
  13
  14 #define ldo_c
  15 #define LUA_CORE
  16
  17 #include "lua.h"
  18
  19 #include "ldebug.h"
  20 #include "ldo.h"
  21 #include "lfunc.h"
  22 #include "lgc.h"
  23 #include "lmem.h"
  24 #include "lobject.h"
  25 #include "lopcodes.h"
  26 #include "lparser.h"
  27 #include "lstate.h"
  28 #include "lstring.h"
  29 #include "ltable.h"
  30 #include "ltm.h"
  31 #include "lundump.h"
  32 #include "lvm.h"
  33 #include "lzio.h"
  34
  35
  36
  37
  38 /*
  39 ** {======================================================
  40 ** Error-recovery functions
  41 ** =======================================================
  42 */
  43
  44
  45 /* chain list of long jump buffers */
  46 struct lua_longjmp {
  47   struct lua_longjmp *previous;
  48   luai_jmpbuf b;
  49   volatile int status;  /* error code */
  50 };
  51
  52
  53 void luaD_seterrorobj (lua_State *L, int errcode, StkId oldtop) {
  54   switch (errcode) {
  55     case LUA_ERRMEM: {
  56       setsvalue2s(L, oldtop, luaS_newliteral(L, MEMERRMSG));
  57       break;
  58     }
  59     case LUA_ERRERR: {
  60       setsvalue2s(L, oldtop, luaS_newliteral(L, "error in error handling"));
  61       break;
  62     }
  63     case LUA_ERRSYNTAX:
  64     case LUA_ERRRUN: {
  65       setobjs2s(L, oldtop, L->top - 1);  /* error message on current top */
  66       break;
  67     }
  68   }
  69   L->top = oldtop + 1;
  70 }
  71
  72
  73 static void restore_stack_limit (lua_State *L) {
  74   lua_assert(L->stack_last - L->stack == L->stacksize - EXTRA_STACK - 1);
  75   if (L->size_ci > LUAI_MAXCALLS) {  /* there was an overflow? */
  76     int inuse = cast_int(L->ci - L->base_ci);
  77     if (inuse + 1 < LUAI_MAXCALLS)  /* can `undo' overflow? */
  78       luaD_reallocCI(L, LUAI_MAXCALLS);
  79   }
  80 }
  81
  82
  83 static void resetstack (lua_State *L, int status) {
  84   L->ci = L->base_ci;
  85   L->base = L->ci->base;
  86   luaF_close(L, L->base);  /* close eventual pending closures */
  87   luaD_seterrorobj(L, status, L->base);
  88   L->nCcalls = L->baseCcalls;
  89   L->allowhook = 1;
  90   restore_stack_limit(L);
  91   L->errfunc = 0;
  92   L->errorJmp = NULL;
  93 }
  94
  95
  96 void luaD_throw (lua_State *L, int errcode) {
  97   if (L->errorJmp) {
  98     L->errorJmp->status = errcode;
  99     LUAI_THROW(L, L->errorJmp);
 100   }
 101   else {
 102     L->status = cast_byte(errcode);
 103     if (G(L)->panic) {
 104       resetstack(L, errcode);
 105       lua_unlock(L);
 106       G(L)->panic(L);
 107     }
 108     exit(EXIT_FAILURE);
 109   }
 110 }
 111
 112
 113 int luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud) {
 114   struct lua_longjmp lj;
 115   lj.status = 0;
 116   lj.previous = L->errorJmp;  /* chain new error handler */
 117   L->errorJmp = &lj;
 118   LUAI_TRY(L, &lj,
 119     (*f)(L, ud);
 120   );
 121   L->errorJmp = lj.previous;  /* restore old error handler */
 122   return lj.status;
 123 }
 124
 125 /* }====================================================== */
 126
 127
 128 static void correctstack (lua_State *L, TValue *oldstack) {
 129   CallInfo *ci;
 130   GCObject *up;
 131   L->top = (L->top - oldstack) + L->stack;
 132   for (up = L->openupval; up != NULL; up = up->gch.next)
 133     gco2uv(up)->v = (gco2uv(up)->v - oldstack) + L->stack;
 134   for (ci = L->base_ci; ci <= L->ci; ci++) {
 135     ci->top = (ci->top - oldstack) + L->stack;
 136     ci->base = (ci->base - oldstack) + L->stack;
 137     ci->func = (ci->func - oldstack) + L->stack;
 138   }
 139   L->base = (L->base - oldstack) + L->stack;
 140 }
 141
 142
 143 void luaD_reallocstack (lua_State *L, int newsize) {
 144   TValue *oldstack = L->stack;
 145   int realsize = newsize + 1 + EXTRA_STACK;
 146   lua_assert(L->stack_last - L->stack == L->stacksize - EXTRA_STACK - 1);
 147   luaM_reallocvector(L, L->stack, L->stacksize, realsize, TValue);
 148   L->stacksize = realsize;
 149   L->stack_last = L->stack+newsize;
 150   correctstack(L, oldstack);
 151 }
 152
 153
 154 void luaD_reallocCI (lua_State *L, int newsize) {
 155   CallInfo *oldci = L->base_ci;
 156   luaM_reallocvector(L, L->base_ci, L->size_ci, newsize, CallInfo);
 157   L->size_ci = newsize;
 158   L->ci = (L->ci - oldci) + L->base_ci;
 159   L->end_ci = L->base_ci + L->size_ci - 1;
 160 }
 161
 162
 163 void luaD_growstack (lua_State *L, int n) {
 164   if (n <= L->stacksize)  /* double size is enough? */
 165     luaD_reallocstack(L, 2*L->stacksize);
 166   else
 167     luaD_reallocstack(L, L->stacksize + n);
 168 }
 169
 170
 171 static CallInfo *growCI (lua_State *L) {
 172   if (L->size_ci > LUAI_MAXCALLS)  /* overflow while handling overflow? */
 173     luaD_throw(L, LUA_ERRERR);
 174   else {
 175     luaD_reallocCI(L, 2*L->size_ci);
 176     if (L->size_ci > LUAI_MAXCALLS)
 177       luaG_runerror(L, "stack overflow");
 178   }
 179   return ++L->ci;
 180 }
 181
 182
 183 void luaD_callhook (lua_State *L, int event, int line) {
 184   lua_Hook hook = L->hook;
 185   if (hook && L->allowhook) {
 186     ptrdiff_t top = savestack(L, L->top);
 187     ptrdiff_t ci_top = savestack(L, L->ci->top);
 188     lua_Debug ar;
 189     ar.event = event;
 190     ar.currentline = line;
 191     if (event == LUA_HOOKTAILRET)
 192       ar.i_ci = 0;  /* tail call; no debug information about it */
 193     else
 194       ar.i_ci = cast_int(L->ci - L->base_ci);
 195     luaD_checkstack(L, LUA_MINSTACK);  /* ensure minimum stack size */
 196     L->ci->top = L->top + LUA_MINSTACK;
 197     lua_assert(L->ci->top <= L->stack_last);
 198     L->allowhook = 0;  /* cannot call hooks inside a hook */
 199     lua_unlock(L);
 200     (*hook)(L, &ar);
 201     lua_lock(L);
 202     lua_assert(!L->allowhook);
 203     L->allowhook = 1;
 204     L->ci->top = restorestack(L, ci_top);
 205     L->top = restorestack(L, top);
 206   }
 207 }
 208
 209
 210 static StkId adjust_varargs (lua_State *L, Proto *p, int actual) {
 211   int i;
 212   int nfixargs = p->numparams;
 213   Table *htab = NULL;
 214   StkId base, fixed;
 215   for (; actual < nfixargs; ++actual)
 216     setnilvalue(L->top++);
 217 #if defined(LUA_COMPAT_VARARG)
 218   if (p->is_vararg & VARARG_NEEDSARG) { /* compat. with old-style vararg? */
 219     int nvar = actual - nfixargs;  /* number of extra arguments */
 220     lua_assert(p->is_vararg & VARARG_HASARG);
 221     luaC_checkGC(L);
 222     luaD_checkstack(L, p->maxstacksize);
 223     htab = luaH_new(L, nvar, 1);  /* create `arg' table */
 224     for (i=0; i<nvar; i++)  /* put extra arguments into `arg' table */
 225       setobj2n(L, luaH_setnum(L, htab, i+1), L->top - nvar + i);
 226     /* store counter in field `n' */
 227     setnvalue(luaH_setstr(L, htab, luaS_newliteral(L, "n")), cast_num(nvar));
 228   }
 229 #endif
 230   /* move fixed parameters to final position */
 231   fixed = L->top - actual;  /* first fixed argument */
 232   base = L->top;  /* final position of first argument */
 233   for (i=0; i<nfixargs; i++) {
 234     setobjs2s(L, L->top++, fixed+i);
 235     setnilvalue(fixed+i);
 236   }
 237   /* add `arg' parameter */
 238   if (htab) {
 239     sethvalue(L, L->top++, htab);
 240     lua_assert(iswhite(obj2gco(htab)));
 241   }
 242   return base;
 243 }
 244
 245
 246 static StkId tryfuncTM (lua_State *L, StkId func) {
 247   const TValue *tm = luaT_gettmbyobj(L, func, TM_CALL);
 248   StkId p;
 249   ptrdiff_t funcr = savestack(L, func);
 250   if (!ttisfunction(tm))
 251     luaG_typeerror(L, func, "call");
 252   /* Open a hole inside the stack at `func' */
 253   for (p = L->top; p > func; p--) setobjs2s(L, p, p-1);
 254   incr_top(L);
 255   func = restorestack(L, funcr);  /* previous call may change stack */
 256   setobj2s(L, func, tm);  /* tag method is the new function to be called */
 257   return func;
 258 }
 259
 260
 261
 262 #define inc_ci(L) \
 263   ((L->ci == L->end_ci) ? growCI(L) : \
 264    (condhardstacktests(luaD_reallocCI(L, L->size_ci)), ++L->ci))
 265
 266
 267 int luaD_precall (lua_State *L, StkId func, int nresults) {
 268   LClosure *cl;
 269   ptrdiff_t funcr;
 270   if (!ttisfunction(func)) /* `func' is not a function? */
 271     func = tryfuncTM(L, func);  /* check the `function' tag method */
 272   funcr = savestack(L, func);
 273   cl = &clvalue(func)->l;
 274   L->ci->savedpc = L->savedpc;
 275   if (!cl->isC) {  /* Lua function? prepare its call */
 276     CallInfo *ci;
 277     StkId st, base;
 278     Proto *p = cl->p;
 279     luaD_checkstack(L, p->maxstacksize);
 280     func = restorestack(L, funcr);
 281     if (!p->is_vararg) {  /* no varargs? */
 282       base = func + 1;
 283       if (L->top > base + p->numparams)
 284         L->top = base + p->numparams;
 285     }
 286     else {  /* vararg function */
 287       int nargs = cast_int(L->top - func) - 1;
 288       base = adjust_varargs(L, p, nargs);
 289       func = restorestack(L, funcr);  /* previous call may change the stack */
 290     }
 291     ci = inc_ci(L);  /* now `enter' new function */
 292     ci->func = func;
 293     L->base = ci->base = base;
 294     ci->top = L->base + p->maxstacksize;
 295     lua_assert(ci->top <= L->stack_last);
 296     L->savedpc = p->code;  /* starting point */
 297     ci->tailcalls = 0;
 298     ci->nresults = nresults;
 299     for (st = L->top; st < ci->top; st++)
 300       setnilvalue(st);
 301     L->top = ci->top;
 302     if (L->hookmask & LUA_MASKCALL) {
 303       L->savedpc++;  /* hooks assume 'pc' is already incremented */
 304       luaD_callhook(L, LUA_HOOKCALL, -1);
 305       L->savedpc--;  /* correct 'pc' */
 306     }
 307     return PCRLUA;
 308   }
 309   else {  /* if is a C function, call it */
 310     CallInfo *ci;
 311     int n;
 312     luaD_checkstack(L, LUA_MINSTACK);  /* ensure minimum stack size */
 313     ci = inc_ci(L);  /* now `enter' new function */
 314     ci->func = restorestack(L, funcr);
 315     L->base = ci->base = ci->func + 1;
 316     ci->top = L->top + LUA_MINSTACK;
 317     lua_assert(ci->top <= L->stack_last);
 318     ci->nresults = nresults;
 319     if (L->hookmask & LUA_MASKCALL)
 320       luaD_callhook(L, LUA_HOOKCALL, -1);
 321     lua_unlock(L);
 322     n = (*curr_func(L)->c.f)(L);  /* do the actual call */
 323     lua_lock(L);
 324     if (n < 0)  /* yielding? */
 325       return PCRYIELD;
 326     else {
 327       luaD_poscall(L, L->top - n);
 328       return PCRC;
 329     }
 330   }
 331 }
 332
 333
 334 static StkId callrethooks (lua_State *L, StkId firstResult) {
 335   ptrdiff_t fr = savestack(L, firstResult);  /* next call may change stack */
 336   luaD_callhook(L, LUA_HOOKRET, -1);
 337   if (f_isLua(L->ci)) {  /* Lua function? */
 338     while ((L->hookmask & LUA_MASKRET) && L->ci->tailcalls--) /* tail calls */
 339       luaD_callhook(L, LUA_HOOKTAILRET, -1);
 340   }
 341   return restorestack(L, fr);
 342 }
 343
 344
 345 int luaD_poscall (lua_State *L, StkId firstResult) {
 346   StkId res;
 347   int wanted, i;
 348   CallInfo *ci;
 349   if (L->hookmask & LUA_MASKRET)
 350     firstResult = callrethooks(L, firstResult);
 351   ci = L->ci--;
 352   res = ci->func;  /* res == final position of 1st result */
 353   wanted = ci->nresults;
 354   L->base = (ci - 1)->base;  /* restore base */
 355   L->savedpc = (ci - 1)->savedpc;  /* restore savedpc */
 356   /* move results to correct place */
 357   for (i = wanted; i != 0 && firstResult < L->top; i--)
 358     setobjs2s(L, res++, firstResult++);
 359   while (i-- > 0)
 360     setnilvalue(res++);
 361   L->top = res;
 362   return (wanted - LUA_MULTRET);  /* 0 iff wanted == LUA_MULTRET */
 363 }
 364
 365
 366 /*
 367 ** Call a function (C or Lua). The function to be called is at *func.
 368 ** The arguments are on the stack, right after the function.
 369 ** When returns, all the results are on the stack, starting at the original
 370 ** function position.
 371 */
 372 void luaD_call (lua_State *L, StkId func, int nResults) {
 373   if (++L->nCcalls >= LUAI_MAXCCALLS) {
 374     if (L->nCcalls == LUAI_MAXCCALLS)
 375       luaG_runerror(L, "C stack overflow");
 376     else if (L->nCcalls >= (LUAI_MAXCCALLS + (LUAI_MAXCCALLS>>3)))
 377       luaD_throw(L, LUA_ERRERR);  /* error while handing stack error */
 378   }
 379   if (luaD_precall(L, func, nResults) == PCRLUA)  /* is a Lua function? */
 380     luaV_execute(L, 1);  /* call it */
 381   L->nCcalls--;
 382   luaC_checkGC(L);
 383 }
 384
 385
 386 static void resume (lua_State *L, void *ud) {
 387   StkId firstArg = cast(StkId, ud);
 388   CallInfo *ci = L->ci;
 389   if (L->status == 0) {  /* start coroutine? */
 390     lua_assert(ci == L->base_ci && firstArg > L->base);
 391     if (luaD_precall(L, firstArg - 1, LUA_MULTRET) != PCRLUA)
 392       return;
 393   }
 394   else {  /* resuming from previous yield */
 395     lua_assert(L->status == LUA_YIELD);
 396     L->status = 0;
 397     if (!f_isLua(ci)) {  /* `common' yield? */
 398       /* finish interrupted execution of `OP_CALL' */
 399       lua_assert(GET_OPCODE(*((ci-1)->savedpc - 1)) == OP_CALL ||
 400                  GET_OPCODE(*((ci-1)->savedpc - 1)) == OP_TAILCALL);
 401       if (luaD_poscall(L, firstArg))  /* complete it... */
 402         L->top = L->ci->top;  /* and correct top if not multiple results */
 403     }
 404     else  /* yielded inside a hook: just continue its execution */
 405       L->base = L->ci->base;
 406   }
 407   luaV_execute(L, cast_int(L->ci - L->base_ci));
 408 }
 409
 410
 411 static int resume_error (lua_State *L, const char *msg) {
 412   L->top = L->ci->base;
 413   setsvalue2s(L, L->top, luaS_new(L, msg));
 414   incr_top(L);
 415   lua_unlock(L);
 416   return LUA_ERRRUN;
 417 }
 418
 419
 420 LUA_API int lua_resume (lua_State *L, int nargs) {
 421   int status;
 422   lua_lock(L);
 423   if (L->status != LUA_YIELD && (L->status != 0 || L->ci != L->base_ci))
 424       return resume_error(L, "cannot resume non-suspended coroutine");
 425   if (L->nCcalls >= LUAI_MAXCCALLS)
 426     return resume_error(L, "C stack overflow");
 427   luai_userstateresume(L, nargs);
 428   lua_assert(L->errfunc == 0);
 429   L->baseCcalls = ++L->nCcalls;
 430   status = luaD_rawrunprotected(L, resume, L->top - nargs);
 431   if (status != 0) {  /* error? */
 432     L->status = cast_byte(status);  /* mark thread as `dead' */
 433     luaD_seterrorobj(L, status, L->top);
 434     L->ci->top = L->top;
 435   }
 436   else {
 437     lua_assert(L->nCcalls == L->baseCcalls);
 438     status = L->status;
 439   }
 440   --L->nCcalls;
 441   lua_unlock(L);
 442   return status;
 443 }
 444
 445
 446 LUA_API int lua_yield (lua_State *L, int nresults) {
 447   luai_userstateyield(L, nresults);
 448   lua_lock(L);
 449   if (L->nCcalls > L->baseCcalls)
 450     luaG_runerror(L, "attempt to yield across metamethod/C-call boundary");
 451   L->base = L->top - nresults;  /* protect stack slots below */
 452   L->status = LUA_YIELD;
 453   lua_unlock(L);
 454   return -1;
 455 }
 456
 457
 458 int luaD_pcall (lua_State *L, Pfunc func, void *u,
 459                 ptrdiff_t old_top, ptrdiff_t ef) {
 460   int status;
 461   unsigned short oldnCcalls = L->nCcalls;
 462   ptrdiff_t old_ci = saveci(L, L->ci);
 463   lu_byte old_allowhooks = L->allowhook;
 464   ptrdiff_t old_errfunc = L->errfunc;
 465   L->errfunc = ef;
 466   status = luaD_rawrunprotected(L, func, u);
 467   if (status != 0) {  /* an error occurred? */
 468     StkId oldtop = restorestack(L, old_top);
 469     luaF_close(L, oldtop);  /* close eventual pending closures */
 470     luaD_seterrorobj(L, status, oldtop);
 471     L->nCcalls = oldnCcalls;
 472     L->ci = restoreci(L, old_ci);
 473     L->base = L->ci->base;
 474     L->savedpc = L->ci->savedpc;
 475     L->allowhook = old_allowhooks;
 476     restore_stack_limit(L);
 477   }
 478   L->errfunc = old_errfunc;
 479   return status;
 480 }
 481
 482
 483
 484 /*
 485 ** Execute a protected parser.
 486 */
 487 struct SParser {  /* data to `f_parser' */
 488   ZIO *z;
 489   Mbuffer buff;  /* buffer to be used by the scanner */
 490   const char *name;
 491 };
 492
 493 static void f_parser (lua_State *L, void *ud) {
 494   int i;
 495   Proto *tf;
 496   Closure *cl;
 497   struct SParser *p = cast(struct SParser *, ud);
 498   int c = luaZ_lookahead(p->z);
 499   luaC_checkGC(L);
 500   tf = ((c == LUA_SIGNATURE[0]) ? luaU_undump : luaY_parser)(L, p->z,
 501                                                              &p->buff, p->name);
 502   cl = luaF_newLclosure(L, tf->nups, hvalue(gt(L)));
 503   cl->l.p = tf;
 504   for (i = 0; i < tf->nups; i++)  /* initialize eventual upvalues */
 505     cl->l.upvals[i] = luaF_newupval(L);
 506   setclvalue(L, L->top, cl);
 507   incr_top(L);
 508 }
 509
 510
 511 int luaD_protectedparser (lua_State *L, ZIO *z, const char *name) {
 512   struct SParser p;
 513   int status;
 514   p.z = z; p.name = name;
 515   luaZ_initbuffer(L, &p.buff);
 516   status = luaD_pcall(L, f_parser, &p, savestack(L, L->top), L->errfunc);
 517   luaZ_freebuffer(L, &p.buff);
 518   return status;
 519 }
 520
 521