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 

     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 "ldebug.h"

    18 #include "ldo.h"

    19 #include "lfunc.h"

    20 #include "lgc.h"

    21 #include "lmem.h"

    22 #include "lobject.h"

    23 #include "lopcodes.h"

    24 #include "lparser.h"

    25 #include "lstate.h"

    26 #include "lstring.h"

    27 #include "ltable.h"

    28 #include "ltm.h"

    29 #include "lundump.h"

    30 #include "lvm.h"

    31 #include "lzio.h"

    32 

    33 

    34 

    35 

    36 /*

    37 ** {======================================================

    38 ** Error-recovery functions

    39 ** =======================================================

    40 */

    41 

    42 

    43 /* chain list of long jump buffers */

    44 struct lua_longjmp {

    45   struct lua_longjmp *previous;

    46   luai_jmpbuf b;

    47   volatile int status;  /* error code */

    48 };

    49 

    50 

    51 void luaD_seterrorobj (lua_State *L, int errcode, StkId oldtop) {

    52   switch (errcode) {

    53     case LUA_ERRMEM: {

    54       setsvalue2s(L, oldtop, luaS_newliteral(L, MEMERRMSG));

    55       break;

    56     }

    57     case LUA_ERRERR: {

    58       setsvalue2s(L, oldtop, luaS_newliteral(L, "error in error handling"));

    59       break;

    60     }

    61     case LUA_ERRSYNTAX:

    62     case LUA_ERRRUN: {

    63       setobjs2s(L, oldtop, L->top - 1);  /* error message on current top */

    64       break;

    65     }

    66   }

    67   L->top = oldtop + 1;

    68 }

    69 

    70 

    71 static void restore_stack_limit (lua_State *L) {

    72   lua_assert(L->stack_last - L->stack == L->stacksize - EXTRA_STACK - 1);

    73   if (L->size_ci > LUAI_MAXCALLS) {  /* there was an overflow? */

    74     int inuse = cast_int(L->ci - L->base_ci);

    75     if (inuse + 1 < LUAI_MAXCALLS)  /* can `undo' overflow? */

    76       luaD_reallocCI(L, LUAI_MAXCALLS);

    77   }

    78 }

    79 

    80 

    81 static void resetstack (lua_State *L, int status) {

    82   L->ci = L->base_ci;

    83   L->base = L->ci->base;

    84   luaF_close(L, L->base);  /* close eventual pending closures */

    85   luaD_seterrorobj(L, status, L->base);

    86   L->nCcalls = L->baseCcalls;

    87   L->allowhook = 1;

    88   restore_stack_limit(L);

    89   L->errfunc = 0;

    90   L->errorJmp = NULL;

    91 }

    92 

    93 

    94 void luaD_throw (lua_State *L, int errcode) {

    95   if (L->errorJmp) {

    96     L->errorJmp->status = errcode;

    97     LUAI_THROW(L, L->errorJmp);

    98   }

    99   else {

   100     L->status = cast_byte(errcode);

   101     if (G(L)->panic) {

   102       resetstack(L, errcode);

   103       lua_unlock(L);

   104       G(L)->panic(L);

   105     }

   106     exit(EXIT_FAILURE);

   107   }

   108 }

   109 

   110 

   111 int luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud) {

   112   struct lua_longjmp lj;

   113   lj.status = 0;

   114   lj.previous = L->errorJmp;  /* chain new error handler */

   115   L->errorJmp = &lj;

   116   LUAI_TRY(L, &lj,

   117     (*f)(L, ud);

   118   );

   119   L->errorJmp = lj.previous;  /* restore old error handler */

   120   return lj.status;

   121 }

   122 

   123 /* }====================================================== */

   124 

   125 

   126 static void correctstack (lua_State *L, TValue *oldstack) {

   127   CallInfo *ci;

   128   GCObject *up;

   129   L->top = (L->top - oldstack) + L->stack;

   130   for (up = L->openupval; up != NULL; up = up->gch.next)

   131     gco2uv(up)->v = (gco2uv(up)->v - oldstack) + L->stack;

   132   for (ci = L->base_ci; ci <= L->ci; ci++) {

   133     ci->top = (ci->top - oldstack) + L->stack;

   134     ci->base = (ci->base - oldstack) + L->stack;

   135     ci->func = (ci->func - oldstack) + L->stack;

   136   }

   137   L->base = (L->base - oldstack) + L->stack;

   138 }

   139 

   140 

   141 void luaD_reallocstack (lua_State *L, int newsize) {

   142   TValue *oldstack = L->stack;

   143   int realsize = newsize + 1 + EXTRA_STACK;

   144   lua_assert(L->stack_last - L->stack == L->stacksize - EXTRA_STACK - 1);

   145   luaM_reallocvector(L, L->stack, L->stacksize, realsize, TValue);

   146   L->stacksize = realsize;

   147   L->stack_last = L->stack+newsize;

   148   correctstack(L, oldstack);

   149 }

   150 

   151 

   152 void luaD_reallocCI (lua_State *L, int newsize) {

   153   CallInfo *oldci = L->base_ci;

   154   luaM_reallocvector(L, L->base_ci, L->size_ci, newsize, CallInfo);

   155   L->size_ci = newsize;

   156   L->ci = (L->ci - oldci) + L->base_ci;

   157   L->end_ci = L->base_ci + L->size_ci - 1;

   158 }

   159 

   160 

   161 void luaD_growstack (lua_State *L, int n) {

   162   if (n <= L->stacksize)  /* double size is enough? */

   163     luaD_reallocstack(L, 2*L->stacksize);

   164   else

   165     luaD_reallocstack(L, L->stacksize + n);

   166 }

   167 

   168 

   169 static CallInfo *growCI (lua_State *L) {

   170   if (L->size_ci > LUAI_MAXCALLS)  /* overflow while handling overflow? */

   171     luaD_throw(L, LUA_ERRERR);

   172   else {

   173     luaD_reallocCI(L, 2*L->size_ci);

   174     if (L->size_ci > LUAI_MAXCALLS)

   175       luaG_runerror(L, "stack overflow");

   176   }

   177   return ++L->ci;

   178 }

   179 

   180 

   181 void luaD_callhook (lua_State *L, int event, int line) {

   182   lua_Hook hook = L->hook;

   183   if (hook && L->allowhook) {

   184     ptrdiff_t top = savestack(L, L->top);

   185     ptrdiff_t ci_top = savestack(L, L->ci->top);

   186     lua_Debug ar;

   187     ar.event = event;

   188     ar.currentline = line;

   189     if (event == LUA_HOOKTAILRET)

   190       ar.i_ci = 0;  /* tail call; no debug information about it */

   191     else

   192       ar.i_ci = cast_int(L->ci - L->base_ci);

   193     luaD_checkstack(L, LUA_MINSTACK);  /* ensure minimum stack size */

   194     L->ci->top = L->top + LUA_MINSTACK;

   195     lua_assert(L->ci->top <= L->stack_last);

   196     L->allowhook = 0;  /* cannot call hooks inside a hook */

   197     lua_unlock(L);

   198     (*hook)(L, &ar);

   199     lua_lock(L);

   200     lua_assert(!L->allowhook);

   201     L->allowhook = 1;

   202     L->ci->top = restorestack(L, ci_top);

   203     L->top = restorestack(L, top);

   204   }

   205 }

   206 

   207 

   208 static StkId adjust_varargs (lua_State *L, Proto *p, int actual) {

   209   int i;

   210   int nfixargs = p->numparams;

   211   Table *htab = NULL;

   212   StkId base, fixed;

   213   for (; actual < nfixargs; ++actual)

   214     setnilvalue(L->top++);

   215 #if defined(LUA_COMPAT_VARARG)

   216   if (p->is_vararg & VARARG_NEEDSARG) { /* compat. with old-style vararg? */

   217     int nvar = actual - nfixargs;  /* number of extra arguments */

   218     lua_assert(p->is_vararg & VARARG_HASARG);

   219     luaC_checkGC(L);

   220     htab = luaH_new(L, nvar, 1);  /* create `arg' table */

   221     for (i=0; i<nvar; i++)  /* put extra arguments into `arg' table */

   222       setobj2n(L, luaH_setnum(L, htab, i+1), L->top - nvar + i);

   223     /* store counter in field `n' */

   224     setnvalue(luaH_setstr(L, htab, luaS_newliteral(L, "n")), cast_num(nvar));

   225   }

   226 #endif

   227   /* move fixed parameters to final position */

   228   fixed = L->top - actual;  /* first fixed argument */

   229   base = L->top;  /* final position of first argument */

   230   for (i=0; i<nfixargs; i++) {

   231     setobjs2s(L, L->top++, fixed+i);

   232     setnilvalue(fixed+i);

   233   }

   234   /* add `arg' parameter */

   235   if (htab) {

   236     sethvalue(L, L->top++, htab);

   237     lua_assert(iswhite(obj2gco(htab)));

   238   }

   239   return base;

   240 }

   241 

   242 

   243 static StkId tryfuncTM (lua_State *L, StkId func) {

   244   const TValue *tm = luaT_gettmbyobj(L, func, TM_CALL);

   245   StkId p;

   246   ptrdiff_t funcr = savestack(L, func);

   247   if (!ttisfunction(tm))

   248     luaG_typeerror(L, func, "call");

   249   /* Open a hole inside the stack at `func' */

   250   for (p = L->top; p > func; p--) setobjs2s(L, p, p-1);

   251   incr_top(L);

   252   func = restorestack(L, funcr);  /* previous call may change stack */

   253   setobj2s(L, func, tm);  /* tag method is the new function to be called */

   254   return func;

   255 }

   256 

   257 

   258 

   259 #define inc_ci(L) \

   260   ((L->ci == L->end_ci) ? growCI(L) : \

   261    (condhardstacktests(luaD_reallocCI(L, L->size_ci)), ++L->ci))

   262 

   263 

   264 int luaD_precall (lua_State *L, StkId func, int nresults) {

   265   LClosure *cl;

   266   ptrdiff_t funcr;

   267   if (!ttisfunction(func)) /* `func' is not a function? */

   268     func = tryfuncTM(L, func);  /* check the `function' tag method */

   269   funcr = savestack(L, func);

   270   cl = &clvalue(func)->l;

   271   L->ci->savedpc = L->savedpc;

   272   if (!cl->isC) {  /* Lua function? prepare its call */

   273     CallInfo *ci;

   274     StkId st, base;

   275     Proto *p = cl->p;

   276     luaD_checkstack(L, p->maxstacksize);

   277     func = restorestack(L, funcr);

   278     if (!p->is_vararg) {  /* no varargs? */

   279       base = func + 1;

   280       if (L->top > base + p->numparams)

   281         L->top = base + p->numparams;

   282     }

   283     else {  /* vararg function */

   284       int nargs = cast_int(L->top - func) - 1;

   285       base = adjust_varargs(L, p, nargs);

   286       func = restorestack(L, funcr);  /* previous call may change the stack */

   287     }

   288     ci = inc_ci(L);  /* now `enter' new function */

   289     ci->func = func;

   290     L->base = ci->base = base;

   291     ci->top = L->base + p->maxstacksize;

   292     lua_assert(ci->top <= L->stack_last);

   293     L->savedpc = p->code;  /* starting point */

   294     ci->tailcalls = 0;

   295     ci->nresults = nresults;

   296     for (st = L->top; st < ci->top; st++)

   297       setnilvalue(st);

   298     L->top = ci->top;

   299     if (L->hookmask & LUA_MASKCALL) {

   300       L->savedpc++;  /* hooks assume 'pc' is already incremented */

   301       luaD_callhook(L, LUA_HOOKCALL, -1);

   302       L->savedpc--;  /* correct 'pc' */

   303     }

   304     return PCRLUA;

   305   }

   306   else {  /* if is a C function, call it */

   307     CallInfo *ci;

   308     int n;

   309     luaD_checkstack(L, LUA_MINSTACK);  /* ensure minimum stack size */

   310     ci = inc_ci(L);  /* now `enter' new function */

   311     ci->func = restorestack(L, funcr);

   312     L->base = ci->base = ci->func + 1;

   313     ci->top = L->top + LUA_MINSTACK;

   314     lua_assert(ci->top <= L->stack_last);

   315     ci->nresults = nresults;

   316     if (L->hookmask & LUA_MASKCALL)

   317       luaD_callhook(L, LUA_HOOKCALL, -1);

   318     lua_unlock(L);

   319     n = (*curr_func(L)->c.f)(L);  /* do the actual call */

   320     lua_lock(L);

   321     if (n < 0)  /* yielding? */

   322       return PCRYIELD;

   323     else {

   324       luaD_poscall(L, L->top - n);

   325       return PCRC;

   326     }

   327   }

   328 }

   329 

   330 

   331 static StkId callrethooks (lua_State *L, StkId firstResult) {

   332   ptrdiff_t fr = savestack(L, firstResult);  /* next call may change stack */

   333   luaD_callhook(L, LUA_HOOKRET, -1);

   334   if (f_isLua(L->ci)) {  /* Lua function? */

   335     while ((L->hookmask & LUA_MASKRET) && L->ci->tailcalls--) /* tail calls */

   336       luaD_callhook(L, LUA_HOOKTAILRET, -1);

   337   }

   338   return restorestack(L, fr);

   339 }

   340 

   341 

   342 int luaD_poscall (lua_State *L, StkId firstResult) {

   343   StkId res;

   344   int wanted, i;

   345   CallInfo *ci;

   346   if (L->hookmask & LUA_MASKRET)

   347     firstResult = callrethooks(L, firstResult);

   348   ci = L->ci--;

   349   res = ci->func;  /* res == final position of 1st result */

   350   wanted = ci->nresults;

   351   L->base = (ci - 1)->base;  /* restore base */

   352   L->savedpc = (ci - 1)->savedpc;  /* restore savedpc */

   353   /* move results to correct place */

   354   for (i = wanted; i != 0 && firstResult < L->top; i--)

   355     setobjs2s(L, res++, firstResult++);

   356   while (i-- > 0)

   357     setnilvalue(res++);

   358   L->top = res;

   359   return (wanted - LUA_MULTRET);  /* 0 iff wanted == LUA_MULTRET */

   360 }

   361 

   362 

   363 /*

   364 ** Call a function (C or Lua). The function to be called is at *func.

   365 ** The arguments are on the stack, right after the function.

   366 ** When returns, all the results are on the stack, starting at the original

   367 ** function position.

   368 */ 

   369 void luaD_call (lua_State *L, StkId func, int nResults) {

   370   if (++L->nCcalls >= LUAI_MAXCCALLS) {

   371     if (L->nCcalls == LUAI_MAXCCALLS)

   372       luaG_runerror(L, "C stack overflow");

   373     else if (L->nCcalls >= (LUAI_MAXCCALLS + (LUAI_MAXCCALLS>>3)))

   374       luaD_throw(L, LUA_ERRERR);  /* error while handing stack error */

   375   }

   376   if (luaD_precall(L, func, nResults) == PCRLUA)  /* is a Lua function? */

   377     luaV_execute(L, 1);  /* call it */

   378   L->nCcalls--;

   379   luaC_checkGC(L);

   380 }

   381 

   382 

   383 static void resume (lua_State *L, void *ud) {

   384   StkId firstArg = cast(StkId, ud);

   385   CallInfo *ci = L->ci;

   386   if (L->status == 0) {  /* start coroutine? */

   387     lua_assert(ci == L->base_ci && firstArg > L->base);

   388     if (luaD_precall(L, firstArg - 1, LUA_MULTRET) != PCRLUA)

   389       return;

   390   }

   391   else {  /* resuming from previous yield */

   392     lua_assert(L->status == LUA_YIELD);

   393     L->status = 0;

   394     if (!f_isLua(ci)) {  /* `common' yield? */

   395       /* finish interrupted execution of `OP_CALL' */

   396       lua_assert(GET_OPCODE(*((ci-1)->savedpc - 1)) == OP_CALL ||

   397                  GET_OPCODE(*((ci-1)->savedpc - 1)) == OP_TAILCALL);

   398       if (luaD_poscall(L, firstArg))  /* complete it... */

   399         L->top = L->ci->top;  /* and correct top if not multiple results */

   400     }

   401     else  /* yielded inside a hook: just continue its execution */

   402       L->base = L->ci->base;

   403   }

   404   luaV_execute(L, cast_int(L->ci - L->base_ci));

   405 }

   406 

   407 

   408 static int resume_error (lua_State *L, const char *msg) {

   409   L->top = L->ci->base;

   410   setsvalue2s(L, L->top, luaS_new(L, msg));

   411   incr_top(L);

   412   lua_unlock(L);

   413   return LUA_ERRRUN;

   414 }

   415 

   416 

   417 LUA_API int lua_resume (lua_State *L, int nargs) {

   418   int status;

   419   lua_lock(L);

   420   if (L->status != LUA_YIELD && (L->status != 0 || L->ci != L->base_ci))

   421       return resume_error(L, "cannot resume non-suspended coroutine");

   422   if (L->nCcalls >= LUAI_MAXCCALLS)

   423     return resume_error(L, "C stack overflow");

   424   luai_userstateresume(L, nargs);

   425   lua_assert(L->errfunc == 0);

   426   L->baseCcalls = ++L->nCcalls;

   427   status = luaD_rawrunprotected(L, resume, L->top - nargs);

   428   if (status != 0) {  /* error? */

   429     L->status = cast_byte(status);  /* mark thread as `dead' */

   430     luaD_seterrorobj(L, status, L->top);

   431     L->ci->top = L->top;

   432   }

   433   else {

   434     lua_assert(L->nCcalls == L->baseCcalls);

   435     status = L->status;

   436   }

   437   --L->nCcalls;

   438   lua_unlock(L);

   439   return status;

   440 }

   441 

   442 

   443 LUA_API int lua_yield (lua_State *L, int nresults) {

   444   luai_userstateyield(L, nresults);

   445   lua_lock(L);

   446   if (L->nCcalls > L->baseCcalls)

   447     luaG_runerror(L, "attempt to yield across metamethod/C-call boundary");

   448   L->base = L->top - nresults;  /* protect stack slots below */

   449   L->status = LUA_YIELD;

   450   lua_unlock(L);

   451   return -1;

   452 }

   453 

   454 

   455 int luaD_pcall (lua_State *L, Pfunc func, void *u,

   456                 ptrdiff_t old_top, ptrdiff_t ef) {

   457   int status;

   458   unsigned short oldnCcalls = L->nCcalls;

   459   ptrdiff_t old_ci = saveci(L, L->ci);

   460   lu_byte old_allowhooks = L->allowhook;

   461   ptrdiff_t old_errfunc = L->errfunc;

   462   L->errfunc = ef;

   463   status = luaD_rawrunprotected(L, func, u);

   464   if (status != 0) {  /* an error occurred? */

   465     StkId oldtop = restorestack(L, old_top);

   466     luaF_close(L, oldtop);  /* close eventual pending closures */

   467     luaD_seterrorobj(L, status, oldtop);

   468     L->nCcalls = oldnCcalls;

   469     L->ci = restoreci(L, old_ci);

   470     L->base = L->ci->base;

   471     L->savedpc = L->ci->savedpc;

   472     L->allowhook = old_allowhooks;

   473     restore_stack_limit(L);

   474   }

   475   L->errfunc = old_errfunc;

   476   return status;

   477 }

   478 

   479 

   480 

   481 /*

   482 ** Execute a protected parser.

   483 */

   484 struct SParser {  /* data to `f_parser' */

   485   ZIO *z;

   486   Mbuffer buff;  /* buffer to be used by the scanner */

   487   const char *name;

   488 };

   489 

   490 static void f_parser (lua_State *L, void *ud) {

   491   int i;

   492   Proto *tf;

   493   Closure *cl;

   494   struct SParser *p = cast(struct SParser *, ud);

   495   int c = luaZ_lookahead(p->z);

   496   luaC_checkGC(L);

   497   tf = ((c == LUA_SIGNATURE[0]) ? luaU_undump : luaY_parser)(L, p->z,

   498                                                              &p->buff, p->name);

   499   cl = luaF_newLclosure(L, tf->nups, hvalue(gt(L)));

   500   cl->l.p = tf;

   501   for (i = 0; i < tf->nups; i++)  /* initialize eventual upvalues */

   502     cl->l.upvals[i] = luaF_newupval(L);

   503   setclvalue(L, L->top, cl);

   504   incr_top(L);

   505 }

   506 

   507 

   508 int luaD_protectedparser (lua_State *L, ZIO *z, const char *name) {

   509   struct SParser p;

   510   int status;

   511   p.z = z; p.name = name;

   512   luaZ_initbuffer(L, &p.buff);

   513   status = luaD_pcall(L, f_parser, &p, savestack(L, L->top), L->errfunc);

   514   luaZ_freebuffer(L, &p.buff);

   515   return status;

   516 }

   517 

   518