1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/src/lua/ldebug.c	Sat Mar 03 11:07:39 2012 -0600
     1.3 @@ -0,0 +1,638 @@
     1.4 +/*
     1.5 +** $Id: ldebug.c,v 2.29.1.6 2008/05/08 16:56:26 roberto Exp $
     1.6 +** Debug Interface
     1.7 +** See Copyright Notice in lua.h
     1.8 +*/
     1.9 +
    1.10 +
    1.11 +#include <stdarg.h>
    1.12 +#include <stddef.h>
    1.13 +#include <string.h>
    1.14 +
    1.15 +
    1.16 +#define ldebug_c
    1.17 +#define LUA_CORE
    1.18 +
    1.19 +#include "lua.h"
    1.20 +
    1.21 +#include "lapi.h"
    1.22 +#include "lcode.h"
    1.23 +#include "ldebug.h"
    1.24 +#include "ldo.h"
    1.25 +#include "lfunc.h"
    1.26 +#include "lobject.h"
    1.27 +#include "lopcodes.h"
    1.28 +#include "lstate.h"
    1.29 +#include "lstring.h"
    1.30 +#include "ltable.h"
    1.31 +#include "ltm.h"
    1.32 +#include "lvm.h"
    1.33 +
    1.34 +
    1.35 +
    1.36 +static const char *getfuncname (lua_State *L, CallInfo *ci, const char **name);
    1.37 +
    1.38 +
    1.39 +static int currentpc (lua_State *L, CallInfo *ci) {
    1.40 +  if (!isLua(ci)) return -1;  /* function is not a Lua function? */
    1.41 +  if (ci == L->ci)
    1.42 +    ci->savedpc = L->savedpc;
    1.43 +  return pcRel(ci->savedpc, ci_func(ci)->l.p);
    1.44 +}
    1.45 +
    1.46 +
    1.47 +static int currentline (lua_State *L, CallInfo *ci) {
    1.48 +  int pc = currentpc(L, ci);
    1.49 +  if (pc < 0)
    1.50 +    return -1;  /* only active lua functions have current-line information */
    1.51 +  else
    1.52 +    return getline(ci_func(ci)->l.p, pc);
    1.53 +}
    1.54 +
    1.55 +
    1.56 +/*
    1.57 +** this function can be called asynchronous (e.g. during a signal)
    1.58 +*/
    1.59 +LUA_API int lua_sethook (lua_State *L, lua_Hook func, int mask, int count) {
    1.60 +  if (func == NULL || mask == 0) {  /* turn off hooks? */
    1.61 +    mask = 0;
    1.62 +    func = NULL;
    1.63 +  }
    1.64 +  L->hook = func;
    1.65 +  L->basehookcount = count;
    1.66 +  resethookcount(L);
    1.67 +  L->hookmask = cast_byte(mask);
    1.68 +  return 1;
    1.69 +}
    1.70 +
    1.71 +
    1.72 +LUA_API lua_Hook lua_gethook (lua_State *L) {
    1.73 +  return L->hook;
    1.74 +}
    1.75 +
    1.76 +
    1.77 +LUA_API int lua_gethookmask (lua_State *L) {
    1.78 +  return L->hookmask;
    1.79 +}
    1.80 +
    1.81 +
    1.82 +LUA_API int lua_gethookcount (lua_State *L) {
    1.83 +  return L->basehookcount;
    1.84 +}
    1.85 +
    1.86 +
    1.87 +LUA_API int lua_getstack (lua_State *L, int level, lua_Debug *ar) {
    1.88 +  int status;
    1.89 +  CallInfo *ci;
    1.90 +  lua_lock(L);
    1.91 +  for (ci = L->ci; level > 0 && ci > L->base_ci; ci--) {
    1.92 +    level--;
    1.93 +    if (f_isLua(ci))  /* Lua function? */
    1.94 +      level -= ci->tailcalls;  /* skip lost tail calls */
    1.95 +  }
    1.96 +  if (level == 0 && ci > L->base_ci) {  /* level found? */
    1.97 +    status = 1;
    1.98 +    ar->i_ci = cast_int(ci - L->base_ci);
    1.99 +  }
   1.100 +  else if (level < 0) {  /* level is of a lost tail call? */
   1.101 +    status = 1;
   1.102 +    ar->i_ci = 0;
   1.103 +  }
   1.104 +  else status = 0;  /* no such level */
   1.105 +  lua_unlock(L);
   1.106 +  return status;
   1.107 +}
   1.108 +
   1.109 +
   1.110 +static Proto *getluaproto (CallInfo *ci) {
   1.111 +  return (isLua(ci) ? ci_func(ci)->l.p : NULL);
   1.112 +}
   1.113 +
   1.114 +
   1.115 +static const char *findlocal (lua_State *L, CallInfo *ci, int n) {
   1.116 +  const char *name;
   1.117 +  Proto *fp = getluaproto(ci);
   1.118 +  if (fp && (name = luaF_getlocalname(fp, n, currentpc(L, ci))) != NULL)
   1.119 +    return name;  /* is a local variable in a Lua function */
   1.120 +  else {
   1.121 +    StkId limit = (ci == L->ci) ? L->top : (ci+1)->func;
   1.122 +    if (limit - ci->base >= n && n > 0)  /* is 'n' inside 'ci' stack? */
   1.123 +      return "(*temporary)";
   1.124 +    else
   1.125 +      return NULL;
   1.126 +  }
   1.127 +}
   1.128 +
   1.129 +
   1.130 +LUA_API const char *lua_getlocal (lua_State *L, const lua_Debug *ar, int n) {
   1.131 +  CallInfo *ci = L->base_ci + ar->i_ci;
   1.132 +  const char *name = findlocal(L, ci, n);
   1.133 +  lua_lock(L);
   1.134 +  if (name)
   1.135 +      luaA_pushobject(L, ci->base + (n - 1));
   1.136 +  lua_unlock(L);
   1.137 +  return name;
   1.138 +}
   1.139 +
   1.140 +
   1.141 +LUA_API const char *lua_setlocal (lua_State *L, const lua_Debug *ar, int n) {
   1.142 +  CallInfo *ci = L->base_ci + ar->i_ci;
   1.143 +  const char *name = findlocal(L, ci, n);
   1.144 +  lua_lock(L);
   1.145 +  if (name)
   1.146 +      setobjs2s(L, ci->base + (n - 1), L->top - 1);
   1.147 +  L->top--;  /* pop value */
   1.148 +  lua_unlock(L);
   1.149 +  return name;
   1.150 +}
   1.151 +
   1.152 +
   1.153 +static void funcinfo (lua_Debug *ar, Closure *cl) {
   1.154 +  if (cl->c.isC) {
   1.155 +    ar->source = "=[C]";
   1.156 +    ar->linedefined = -1;
   1.157 +    ar->lastlinedefined = -1;
   1.158 +    ar->what = "C";
   1.159 +  }
   1.160 +  else {
   1.161 +    ar->source = getstr(cl->l.p->source);
   1.162 +    ar->linedefined = cl->l.p->linedefined;
   1.163 +    ar->lastlinedefined = cl->l.p->lastlinedefined;
   1.164 +    ar->what = (ar->linedefined == 0) ? "main" : "Lua";
   1.165 +  }
   1.166 +  luaO_chunkid(ar->short_src, ar->source, LUA_IDSIZE);
   1.167 +}
   1.168 +
   1.169 +
   1.170 +static void info_tailcall (lua_Debug *ar) {
   1.171 +  ar->name = ar->namewhat = "";
   1.172 +  ar->what = "tail";
   1.173 +  ar->lastlinedefined = ar->linedefined = ar->currentline = -1;
   1.174 +  ar->source = "=(tail call)";
   1.175 +  luaO_chunkid(ar->short_src, ar->source, LUA_IDSIZE);
   1.176 +  ar->nups = 0;
   1.177 +}
   1.178 +
   1.179 +
   1.180 +static void collectvalidlines (lua_State *L, Closure *f) {
   1.181 +  if (f == NULL || f->c.isC) {
   1.182 +    setnilvalue(L->top);
   1.183 +  }
   1.184 +  else {
   1.185 +    Table *t = luaH_new(L, 0, 0);
   1.186 +    int *lineinfo = f->l.p->lineinfo;
   1.187 +    int i;
   1.188 +    for (i=0; i<f->l.p->sizelineinfo; i++)
   1.189 +      setbvalue(luaH_setnum(L, t, lineinfo[i]), 1);
   1.190 +    sethvalue(L, L->top, t); 
   1.191 +  }
   1.192 +  incr_top(L);
   1.193 +}
   1.194 +
   1.195 +
   1.196 +static int auxgetinfo (lua_State *L, const char *what, lua_Debug *ar,
   1.197 +                    Closure *f, CallInfo *ci) {
   1.198 +  int status = 1;
   1.199 +  if (f == NULL) {
   1.200 +    info_tailcall(ar);
   1.201 +    return status;
   1.202 +  }
   1.203 +  for (; *what; what++) {
   1.204 +    switch (*what) {
   1.205 +      case 'S': {
   1.206 +        funcinfo(ar, f);
   1.207 +        break;
   1.208 +      }
   1.209 +      case 'l': {
   1.210 +        ar->currentline = (ci) ? currentline(L, ci) : -1;
   1.211 +        break;
   1.212 +      }
   1.213 +      case 'u': {
   1.214 +        ar->nups = f->c.nupvalues;
   1.215 +        break;
   1.216 +      }
   1.217 +      case 'n': {
   1.218 +        ar->namewhat = (ci) ? getfuncname(L, ci, &ar->name) : NULL;
   1.219 +        if (ar->namewhat == NULL) {
   1.220 +          ar->namewhat = "";  /* not found */
   1.221 +          ar->name = NULL;
   1.222 +        }
   1.223 +        break;
   1.224 +      }
   1.225 +      case 'L':
   1.226 +      case 'f':  /* handled by lua_getinfo */
   1.227 +        break;
   1.228 +      default: status = 0;  /* invalid option */
   1.229 +    }
   1.230 +  }
   1.231 +  return status;
   1.232 +}
   1.233 +
   1.234 +
   1.235 +LUA_API int lua_getinfo (lua_State *L, const char *what, lua_Debug *ar) {
   1.236 +  int status;
   1.237 +  Closure *f = NULL;
   1.238 +  CallInfo *ci = NULL;
   1.239 +  lua_lock(L);
   1.240 +  if (*what == '>') {
   1.241 +    StkId func = L->top - 1;
   1.242 +    luai_apicheck(L, ttisfunction(func));
   1.243 +    what++;  /* skip the '>' */
   1.244 +    f = clvalue(func);
   1.245 +    L->top--;  /* pop function */
   1.246 +  }
   1.247 +  else if (ar->i_ci != 0) {  /* no tail call? */
   1.248 +    ci = L->base_ci + ar->i_ci;
   1.249 +    lua_assert(ttisfunction(ci->func));
   1.250 +    f = clvalue(ci->func);
   1.251 +  }
   1.252 +  status = auxgetinfo(L, what, ar, f, ci);
   1.253 +  if (strchr(what, 'f')) {
   1.254 +    if (f == NULL) setnilvalue(L->top);
   1.255 +    else setclvalue(L, L->top, f);
   1.256 +    incr_top(L);
   1.257 +  }
   1.258 +  if (strchr(what, 'L'))
   1.259 +    collectvalidlines(L, f);
   1.260 +  lua_unlock(L);
   1.261 +  return status;
   1.262 +}
   1.263 +
   1.264 +
   1.265 +/*
   1.266 +** {======================================================
   1.267 +** Symbolic Execution and code checker
   1.268 +** =======================================================
   1.269 +*/
   1.270 +
   1.271 +#define check(x)		if (!(x)) return 0;
   1.272 +
   1.273 +#define checkjump(pt,pc)	check(0 <= pc && pc < pt->sizecode)
   1.274 +
   1.275 +#define checkreg(pt,reg)	check((reg) < (pt)->maxstacksize)
   1.276 +
   1.277 +
   1.278 +
   1.279 +static int precheck (const Proto *pt) {
   1.280 +  check(pt->maxstacksize <= MAXSTACK);
   1.281 +  check(pt->numparams+(pt->is_vararg & VARARG_HASARG) <= pt->maxstacksize);
   1.282 +  check(!(pt->is_vararg & VARARG_NEEDSARG) ||
   1.283 +              (pt->is_vararg & VARARG_HASARG));
   1.284 +  check(pt->sizeupvalues <= pt->nups);
   1.285 +  check(pt->sizelineinfo == pt->sizecode || pt->sizelineinfo == 0);
   1.286 +  check(pt->sizecode > 0 && GET_OPCODE(pt->code[pt->sizecode-1]) == OP_RETURN);
   1.287 +  return 1;
   1.288 +}
   1.289 +
   1.290 +
   1.291 +#define checkopenop(pt,pc)	luaG_checkopenop((pt)->code[(pc)+1])
   1.292 +
   1.293 +int luaG_checkopenop (Instruction i) {
   1.294 +  switch (GET_OPCODE(i)) {
   1.295 +    case OP_CALL:
   1.296 +    case OP_TAILCALL:
   1.297 +    case OP_RETURN:
   1.298 +    case OP_SETLIST: {
   1.299 +      check(GETARG_B(i) == 0);
   1.300 +      return 1;
   1.301 +    }
   1.302 +    default: return 0;  /* invalid instruction after an open call */
   1.303 +  }
   1.304 +}
   1.305 +
   1.306 +
   1.307 +static int checkArgMode (const Proto *pt, int r, enum OpArgMask mode) {
   1.308 +  switch (mode) {
   1.309 +    case OpArgN: check(r == 0); break;
   1.310 +    case OpArgU: break;
   1.311 +    case OpArgR: checkreg(pt, r); break;
   1.312 +    case OpArgK:
   1.313 +      check(ISK(r) ? INDEXK(r) < pt->sizek : r < pt->maxstacksize);
   1.314 +      break;
   1.315 +  }
   1.316 +  return 1;
   1.317 +}
   1.318 +
   1.319 +
   1.320 +static Instruction symbexec (const Proto *pt, int lastpc, int reg) {
   1.321 +  int pc;
   1.322 +  int last;  /* stores position of last instruction that changed `reg' */
   1.323 +  last = pt->sizecode-1;  /* points to final return (a `neutral' instruction) */
   1.324 +  check(precheck(pt));
   1.325 +  for (pc = 0; pc < lastpc; pc++) {
   1.326 +    Instruction i = pt->code[pc];
   1.327 +    OpCode op = GET_OPCODE(i);
   1.328 +    int a = GETARG_A(i);
   1.329 +    int b = 0;
   1.330 +    int c = 0;
   1.331 +    check(op < NUM_OPCODES);
   1.332 +    checkreg(pt, a);
   1.333 +    switch (getOpMode(op)) {
   1.334 +      case iABC: {
   1.335 +        b = GETARG_B(i);
   1.336 +        c = GETARG_C(i);
   1.337 +        check(checkArgMode(pt, b, getBMode(op)));
   1.338 +        check(checkArgMode(pt, c, getCMode(op)));
   1.339 +        break;
   1.340 +      }
   1.341 +      case iABx: {
   1.342 +        b = GETARG_Bx(i);
   1.343 +        if (getBMode(op) == OpArgK) check(b < pt->sizek);
   1.344 +        break;
   1.345 +      }
   1.346 +      case iAsBx: {
   1.347 +        b = GETARG_sBx(i);
   1.348 +        if (getBMode(op) == OpArgR) {
   1.349 +          int dest = pc+1+b;
   1.350 +          check(0 <= dest && dest < pt->sizecode);
   1.351 +          if (dest > 0) {
   1.352 +            int j;
   1.353 +            /* check that it does not jump to a setlist count; this
   1.354 +               is tricky, because the count from a previous setlist may
   1.355 +               have the same value of an invalid setlist; so, we must
   1.356 +               go all the way back to the first of them (if any) */
   1.357 +            for (j = 0; j < dest; j++) {
   1.358 +              Instruction d = pt->code[dest-1-j];
   1.359 +              if (!(GET_OPCODE(d) == OP_SETLIST && GETARG_C(d) == 0)) break;
   1.360 +            }
   1.361 +            /* if 'j' is even, previous value is not a setlist (even if
   1.362 +               it looks like one) */
   1.363 +            check((j&1) == 0);
   1.364 +          }
   1.365 +        }
   1.366 +        break;
   1.367 +      }
   1.368 +    }
   1.369 +    if (testAMode(op)) {
   1.370 +      if (a == reg) last = pc;  /* change register `a' */
   1.371 +    }
   1.372 +    if (testTMode(op)) {
   1.373 +      check(pc+2 < pt->sizecode);  /* check skip */
   1.374 +      check(GET_OPCODE(pt->code[pc+1]) == OP_JMP);
   1.375 +    }
   1.376 +    switch (op) {
   1.377 +      case OP_LOADBOOL: {
   1.378 +        if (c == 1) {  /* does it jump? */
   1.379 +          check(pc+2 < pt->sizecode);  /* check its jump */
   1.380 +          check(GET_OPCODE(pt->code[pc+1]) != OP_SETLIST ||
   1.381 +                GETARG_C(pt->code[pc+1]) != 0);
   1.382 +        }
   1.383 +        break;
   1.384 +      }
   1.385 +      case OP_LOADNIL: {
   1.386 +        if (a <= reg && reg <= b)
   1.387 +          last = pc;  /* set registers from `a' to `b' */
   1.388 +        break;
   1.389 +      }
   1.390 +      case OP_GETUPVAL:
   1.391 +      case OP_SETUPVAL: {
   1.392 +        check(b < pt->nups);
   1.393 +        break;
   1.394 +      }
   1.395 +      case OP_GETGLOBAL:
   1.396 +      case OP_SETGLOBAL: {
   1.397 +        check(ttisstring(&pt->k[b]));
   1.398 +        break;
   1.399 +      }
   1.400 +      case OP_SELF: {
   1.401 +        checkreg(pt, a+1);
   1.402 +        if (reg == a+1) last = pc;
   1.403 +        break;
   1.404 +      }
   1.405 +      case OP_CONCAT: {
   1.406 +        check(b < c);  /* at least two operands */
   1.407 +        break;
   1.408 +      }
   1.409 +      case OP_TFORLOOP: {
   1.410 +        check(c >= 1);  /* at least one result (control variable) */
   1.411 +        checkreg(pt, a+2+c);  /* space for results */
   1.412 +        if (reg >= a+2) last = pc;  /* affect all regs above its base */
   1.413 +        break;
   1.414 +      }
   1.415 +      case OP_FORLOOP:
   1.416 +      case OP_FORPREP:
   1.417 +        checkreg(pt, a+3);
   1.418 +        /* go through */
   1.419 +      case OP_JMP: {
   1.420 +        int dest = pc+1+b;
   1.421 +        /* not full check and jump is forward and do not skip `lastpc'? */
   1.422 +        if (reg != NO_REG && pc < dest && dest <= lastpc)
   1.423 +          pc += b;  /* do the jump */
   1.424 +        break;
   1.425 +      }
   1.426 +      case OP_CALL:
   1.427 +      case OP_TAILCALL: {
   1.428 +        if (b != 0) {
   1.429 +          checkreg(pt, a+b-1);
   1.430 +        }
   1.431 +        c--;  /* c = num. returns */
   1.432 +        if (c == LUA_MULTRET) {
   1.433 +          check(checkopenop(pt, pc));
   1.434 +        }
   1.435 +        else if (c != 0)
   1.436 +          checkreg(pt, a+c-1);
   1.437 +        if (reg >= a) last = pc;  /* affect all registers above base */
   1.438 +        break;
   1.439 +      }
   1.440 +      case OP_RETURN: {
   1.441 +        b--;  /* b = num. returns */
   1.442 +        if (b > 0) checkreg(pt, a+b-1);
   1.443 +        break;
   1.444 +      }
   1.445 +      case OP_SETLIST: {
   1.446 +        if (b > 0) checkreg(pt, a + b);
   1.447 +        if (c == 0) {
   1.448 +          pc++;
   1.449 +          check(pc < pt->sizecode - 1);
   1.450 +        }
   1.451 +        break;
   1.452 +      }
   1.453 +      case OP_CLOSURE: {
   1.454 +        int nup, j;
   1.455 +        check(b < pt->sizep);
   1.456 +        nup = pt->p[b]->nups;
   1.457 +        check(pc + nup < pt->sizecode);
   1.458 +        for (j = 1; j <= nup; j++) {
   1.459 +          OpCode op1 = GET_OPCODE(pt->code[pc + j]);
   1.460 +          check(op1 == OP_GETUPVAL || op1 == OP_MOVE);
   1.461 +        }
   1.462 +        if (reg != NO_REG)  /* tracing? */
   1.463 +          pc += nup;  /* do not 'execute' these pseudo-instructions */
   1.464 +        break;
   1.465 +      }
   1.466 +      case OP_VARARG: {
   1.467 +        check((pt->is_vararg & VARARG_ISVARARG) &&
   1.468 +             !(pt->is_vararg & VARARG_NEEDSARG));
   1.469 +        b--;
   1.470 +        if (b == LUA_MULTRET) check(checkopenop(pt, pc));
   1.471 +        checkreg(pt, a+b-1);
   1.472 +        break;
   1.473 +      }
   1.474 +      default: break;
   1.475 +    }
   1.476 +  }
   1.477 +  return pt->code[last];
   1.478 +}
   1.479 +
   1.480 +#undef check
   1.481 +#undef checkjump
   1.482 +#undef checkreg
   1.483 +
   1.484 +/* }====================================================== */
   1.485 +
   1.486 +
   1.487 +int luaG_checkcode (const Proto *pt) {
   1.488 +  return (symbexec(pt, pt->sizecode, NO_REG) != 0);
   1.489 +}
   1.490 +
   1.491 +
   1.492 +static const char *kname (Proto *p, int c) {
   1.493 +  if (ISK(c) && ttisstring(&p->k[INDEXK(c)]))
   1.494 +    return svalue(&p->k[INDEXK(c)]);
   1.495 +  else
   1.496 +    return "?";
   1.497 +}
   1.498 +
   1.499 +
   1.500 +static const char *getobjname (lua_State *L, CallInfo *ci, int stackpos,
   1.501 +                               const char **name) {
   1.502 +  if (isLua(ci)) {  /* a Lua function? */
   1.503 +    Proto *p = ci_func(ci)->l.p;
   1.504 +    int pc = currentpc(L, ci);
   1.505 +    Instruction i;
   1.506 +    *name = luaF_getlocalname(p, stackpos+1, pc);
   1.507 +    if (*name)  /* is a local? */
   1.508 +      return "local";
   1.509 +    i = symbexec(p, pc, stackpos);  /* try symbolic execution */
   1.510 +    lua_assert(pc != -1);
   1.511 +    switch (GET_OPCODE(i)) {
   1.512 +      case OP_GETGLOBAL: {
   1.513 +        int g = GETARG_Bx(i);  /* global index */
   1.514 +        lua_assert(ttisstring(&p->k[g]));
   1.515 +        *name = svalue(&p->k[g]);
   1.516 +        return "global";
   1.517 +      }
   1.518 +      case OP_MOVE: {
   1.519 +        int a = GETARG_A(i);
   1.520 +        int b = GETARG_B(i);  /* move from `b' to `a' */
   1.521 +        if (b < a)
   1.522 +          return getobjname(L, ci, b, name);  /* get name for `b' */
   1.523 +        break;
   1.524 +      }
   1.525 +      case OP_GETTABLE: {
   1.526 +        int k = GETARG_C(i);  /* key index */
   1.527 +        *name = kname(p, k);
   1.528 +        return "field";
   1.529 +      }
   1.530 +      case OP_GETUPVAL: {
   1.531 +        int u = GETARG_B(i);  /* upvalue index */
   1.532 +        *name = p->upvalues ? getstr(p->upvalues[u]) : "?";
   1.533 +        return "upvalue";
   1.534 +      }
   1.535 +      case OP_SELF: {
   1.536 +        int k = GETARG_C(i);  /* key index */
   1.537 +        *name = kname(p, k);
   1.538 +        return "method";
   1.539 +      }
   1.540 +      default: break;
   1.541 +    }
   1.542 +  }
   1.543 +  return NULL;  /* no useful name found */
   1.544 +}
   1.545 +
   1.546 +
   1.547 +static const char *getfuncname (lua_State *L, CallInfo *ci, const char **name) {
   1.548 +  Instruction i;
   1.549 +  if ((isLua(ci) && ci->tailcalls > 0) || !isLua(ci - 1))
   1.550 +    return NULL;  /* calling function is not Lua (or is unknown) */
   1.551 +  ci--;  /* calling function */
   1.552 +  i = ci_func(ci)->l.p->code[currentpc(L, ci)];
   1.553 +  if (GET_OPCODE(i) == OP_CALL || GET_OPCODE(i) == OP_TAILCALL ||
   1.554 +      GET_OPCODE(i) == OP_TFORLOOP)
   1.555 +    return getobjname(L, ci, GETARG_A(i), name);
   1.556 +  else
   1.557 +    return NULL;  /* no useful name can be found */
   1.558 +}
   1.559 +
   1.560 +
   1.561 +/* only ANSI way to check whether a pointer points to an array */
   1.562 +static int isinstack (CallInfo *ci, const TValue *o) {
   1.563 +  StkId p;
   1.564 +  for (p = ci->base; p < ci->top; p++)
   1.565 +    if (o == p) return 1;
   1.566 +  return 0;
   1.567 +}
   1.568 +
   1.569 +
   1.570 +void luaG_typeerror (lua_State *L, const TValue *o, const char *op) {
   1.571 +  const char *name = NULL;
   1.572 +  const char *t = luaT_typenames[ttype(o)];
   1.573 +  const char *kind = (isinstack(L->ci, o)) ?
   1.574 +                         getobjname(L, L->ci, cast_int(o - L->base), &name) :
   1.575 +                         NULL;
   1.576 +  if (kind)
   1.577 +    luaG_runerror(L, "attempt to %s %s " LUA_QS " (a %s value)",
   1.578 +                op, kind, name, t);
   1.579 +  else
   1.580 +    luaG_runerror(L, "attempt to %s a %s value", op, t);
   1.581 +}
   1.582 +
   1.583 +
   1.584 +void luaG_concaterror (lua_State *L, StkId p1, StkId p2) {
   1.585 +  if (ttisstring(p1) || ttisnumber(p1)) p1 = p2;
   1.586 +  lua_assert(!ttisstring(p1) && !ttisnumber(p1));
   1.587 +  luaG_typeerror(L, p1, "concatenate");
   1.588 +}
   1.589 +
   1.590 +
   1.591 +void luaG_aritherror (lua_State *L, const TValue *p1, const TValue *p2) {
   1.592 +  TValue temp;
   1.593 +  if (luaV_tonumber(p1, &temp) == NULL)
   1.594 +    p2 = p1;  /* first operand is wrong */
   1.595 +  luaG_typeerror(L, p2, "perform arithmetic on");
   1.596 +}
   1.597 +
   1.598 +
   1.599 +int luaG_ordererror (lua_State *L, const TValue *p1, const TValue *p2) {
   1.600 +  const char *t1 = luaT_typenames[ttype(p1)];
   1.601 +  const char *t2 = luaT_typenames[ttype(p2)];
   1.602 +  if (t1[2] == t2[2])
   1.603 +    luaG_runerror(L, "attempt to compare two %s values", t1);
   1.604 +  else
   1.605 +    luaG_runerror(L, "attempt to compare %s with %s", t1, t2);
   1.606 +  return 0;
   1.607 +}
   1.608 +
   1.609 +
   1.610 +static void addinfo (lua_State *L, const char *msg) {
   1.611 +  CallInfo *ci = L->ci;
   1.612 +  if (isLua(ci)) {  /* is Lua code? */
   1.613 +    char buff[LUA_IDSIZE];  /* add file:line information */
   1.614 +    int line = currentline(L, ci);
   1.615 +    luaO_chunkid(buff, getstr(getluaproto(ci)->source), LUA_IDSIZE);
   1.616 +    luaO_pushfstring(L, "%s:%d: %s", buff, line, msg);
   1.617 +  }
   1.618 +}
   1.619 +
   1.620 +
   1.621 +void luaG_errormsg (lua_State *L) {
   1.622 +  if (L->errfunc != 0) {  /* is there an error handling function? */
   1.623 +    StkId errfunc = restorestack(L, L->errfunc);
   1.624 +    if (!ttisfunction(errfunc)) luaD_throw(L, LUA_ERRERR);
   1.625 +    setobjs2s(L, L->top, L->top - 1);  /* move argument */
   1.626 +    setobjs2s(L, L->top - 1, errfunc);  /* push function */
   1.627 +    incr_top(L);
   1.628 +    luaD_call(L, L->top - 2, 1);  /* call it */
   1.629 +  }
   1.630 +  luaD_throw(L, LUA_ERRRUN);
   1.631 +}
   1.632 +
   1.633 +
   1.634 +void luaG_runerror (lua_State *L, const char *fmt, ...) {
   1.635 +  va_list argp;
   1.636 +  va_start(argp, fmt);
   1.637 +  addinfo(L, luaO_pushvfstring(L, fmt, argp));
   1.638 +  va_end(argp);
   1.639 +  luaG_errormsg(L);
   1.640 +}
   1.641 +