summaryrefslogtreecommitdiffstats
path: root/apps/plugins/lua/ldebug.c
blob: 446f7d1a45d88d4b9c37cff54ac0ad44c04757b9 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
/*
** $Id: ldebug.c,v 2.29.1.6 2008/05/08 16:56:26 roberto Exp $
** Debug Interface
** See Copyright Notice in lua.h
*/


#include <stdarg.h>
#include <stddef.h>
#include <string.h>


#define ldebug_c
#define LUA_CORE

#include "lua.h"

#include "lapi.h"
#include "lcode.h"
#include "ldebug.h"
#include "ldo.h"
#include "lfunc.h"
#include "lobject.h"
#include "lopcodes.h"
#include "lstate.h"
#include "lstring.h"
#include "ltable.h"
#include "ltm.h"
#include "lvm.h"



static const char *getfuncname (lua_State *L, CallInfo *ci, const char **name);


static int currentpc (lua_State *L, CallInfo *ci) {
  if (!isLua(ci)) return -1;  /* function is not a Lua function? */
  if (ci == L->ci)
    ci->savedpc = L->savedpc;
  return pcRel(ci->savedpc, ci_func(ci)->l.p);
}


static int currentline (lua_State *L, CallInfo *ci) {
  int pc = currentpc(L, ci);
  if (pc < 0)
    return -1;  /* only active lua functions have current-line information */
  else
    return getline(ci_func(ci)->l.p, pc);
}


/*
** this function can be called asynchronous (e.g. during a signal)
*/
LUA_API int lua_sethook (lua_State *L, lua_Hook func, int mask, int count) {
  if (func == NULL || mask == 0) {  /* turn off hooks? */
    mask = 0;
    func = NULL;
  }
  L->hook = func;
  L->basehookcount = count;
  resethookcount(L);
  L->hookmask = cast_byte(mask);
  return 1;
}


LUA_API lua_Hook lua_gethook (lua_State *L) {
  return L->hook;
}


LUA_API int lua_gethookmask (lua_State *L) {
  return L->hookmask;
}


LUA_API int lua_gethookcount (lua_State *L) {
  return L->basehookcount;
}


LUA_API int lua_getstack (lua_State *L, int level, lua_Debug *ar) {
  int status;
  CallInfo *ci;
  lua_lock(L);
  for (ci = L->ci; level > 0 && ci > L->base_ci; ci--) {
    level--;
    if (f_isLua(ci))  /* Lua function? */
      level -= ci->tailcalls;  /* skip lost tail calls */
  }
  if (level == 0 && ci > L->base_ci) {  /* level found? */
    status = 1;
    ar->i_ci = cast_int(ci - L->base_ci);
  }
  else if (level < 0) {  /* level is of a lost tail call? */
    status = 1;
    ar->i_ci = 0;
  }
  else status = 0;  /* no such level */
  lua_unlock(L);
  return status;
}


static Proto *getluaproto (CallInfo *ci) {
  return (isLua(ci) ? ci_func(ci)->l.p : NULL);
}


static const char *findlocal (lua_State *L, CallInfo *ci, int n) {
  const char *name;
  Proto *fp = getluaproto(ci);
  if (fp && (name = luaF_getlocalname(fp, n, currentpc(L, ci))) != NULL)
    return name;  /* is a local variable in a Lua function */
  else {
    StkId limit = (ci == L->ci) ? L->top : (ci+1)->func;
    if (limit - ci->base >= n && n > 0)  /* is 'n' inside 'ci' stack? */
      return "(*temporary)";
    else
      return NULL;
  }
}


LUA_API const char *lua_getlocal (lua_State *L, const lua_Debug *ar, int n) {
  CallInfo *ci = L->base_ci + ar->i_ci;
  const char *name = findlocal(L, ci, n);
  lua_lock(L);
  if (name)
      luaA_pushobject(L, ci->base + (n - 1));
  lua_unlock(L);
  return name;
}


LUA_API const char *lua_setlocal (lua_State *L, const lua_Debug *ar, int n) {
  CallInfo *ci = L->base_ci + ar->i_ci;
  const char *name = findlocal(L, ci, n);
  lua_lock(L);
  if (name)
      setobjs2s(L, ci->base + (n - 1), L->top - 1);
  L->top--;  /* pop value */
  lua_unlock(L);
  return name;
}


static void funcinfo (lua_Debug *ar, Closure *cl) {
  if (cl->c.isC) {
    ar->source = "=[C]";
    ar->linedefined = -1;
    ar->lastlinedefined = -1;
    ar->what = "C";
  }
  else {
    ar->source = getstr(cl->l.p->source);
    ar->linedefined = cl->l.p->linedefined;
    ar->lastlinedefined = cl->l.p->lastlinedefined;
    ar->what = (ar->linedefined == 0) ? "main" : "Lua";
  }
  luaO_chunkid(ar->short_src, ar->source, LUA_IDSIZE);
}


static void info_tailcall (lua_Debug *ar) {
  ar->name = ar->namewhat = "";
  ar->what = "tail";
  ar->lastlinedefined = ar->linedefined = ar->currentline = -1;
  ar->source = "=(tail call)";
  luaO_chunkid(ar->short_src, ar->source, LUA_IDSIZE);
  ar->nups = 0;
}


static void collectvalidlines (lua_State *L, Closure *f) {
  if (f == NULL || f->c.isC) {
    setnilvalue(L->top);
  }
  else {
    Table *t = luaH_new(L, 0, 0);
#ifdef LUA_OPTIMIZE_DEBUG
    int line = 0;
    unsigned char *p = f->l.p->packedlineinfo;
    if (p) {
      for (; *p && *p != INFO_FILL_BYTE; ) {
        if (*p & INFO_DELTA_MASK) { /* line delta */
          int delta = *p & INFO_DELTA_6BITS;
          unsigned char sign = *p++ & INFO_SIGN_MASK;
          int shift;
          for (shift = 6; *p & INFO_DELTA_MASK; p++, shift += 7) {
            delta += (*p & INFO_DELTA_7BITS)<<shift;
          }
          line += sign ? -delta : delta+2;
        } else {
          line++;
        }
        p++;
        setbvalue(luaH_setnum(L, t, line), 1);
      }
    }
#else
    int *lineinfo = f->l.p->lineinfo;
    int i;
    for (i=0; i<f->l.p->sizelineinfo; i++)
      setbvalue(luaH_setnum(L, t, lineinfo[i]), 1);
#endif
    sethvalue(L, L->top, t);
  }
  incr_top(L);
}


#ifdef LUA_OPTIMIZE_DEBUG
/*
 * This may seem expensive but this is only accessed frequently in traceexec
 * and the while loop will be executed roughly half the number of non-blank
 * source lines in the Lua function and these tend to be short.
 */
LUAI_FUNC int luaG_getline (const Proto *f, int pc) {
  int line = 0, thispc = 0, nextpc;
  unsigned char *p;

  for (p = f->packedlineinfo; *p && *p != INFO_FILL_BYTE;) {
    if (*p & INFO_DELTA_MASK) { /* line delta */
      int delta = *p & INFO_DELTA_6BITS;
      unsigned char sign = *p++ & INFO_SIGN_MASK;
      int shift;
      for (shift = 6; *p & INFO_DELTA_MASK; p++, shift += 7) {
        delta += (*p & INFO_DELTA_7BITS)<<shift;
      }
      line += sign ? -delta : delta+2;
    } else {
      line++;
    }
    lua_assert(*p<127);
    nextpc = thispc + *p++;
    if (thispc <= pc && pc < nextpc) {
      return line;
    }
    thispc = nextpc;
  }
  lua_assert(0);
  return 0;
}


static int stripdebug (lua_State *L, Proto *f, const int level) {
  int len = 0;
  TString* dummy;
  switch (level) {
    case 3:
      len += f->sizelineinfo;
      f->packedlineinfo = luaM_freearray(L, f->packedlineinfo, f->sizelineinfo, unsigned char);
    case 2:
      len += f->sizelocvars * (sizeof(struct LocVar) + sizeof(dummy->tsv) + sizeof(struct LocVar *));
      f->locvars = luaM_freearray(L, f->locvars, f->sizelocvars, struct LocVar);
      f->upvalues = luaM_freearray(L, f->upvalues, f->sizeupvalues, TString *);
      len += f->sizelocvars * (sizeof(struct LocVar) + sizeof(dummy->tsv) + sizeof(struct LocVar *)) +
             f->sizeupvalues * (sizeof(dummy->tsv) + sizeof(TString *));
      f->sizelocvars = 0;
      f->sizeupvalues = 0;
    case 1:
    default:
      break;
  }
  return len;
}


/* This is a recursive function so it's stack size has been kept to a minimum! */
LUAI_FUNC int luaG_stripdebug (lua_State *L, Proto *f, int level, int recv){
  int len = 0, i;
#ifndef LUA_OPTIMIZE_DEBUG_USER /* gcc doesn't realize level can't be changed */
  level = LUA_OPTIMIZE_DEBUG;
#endif
  if (recv > 0 && f->sizep != 0) {
    /* recv limits recursion depth */
    for(i=0;i<f->sizep;i++) len += luaG_stripdebug(L, f->p[i], level, --recv);
  }
  len += stripdebug (L, f, level);
  return len;
}
#endif


static int auxgetinfo (lua_State *L, const char *what, lua_Debug *ar,
                    Closure *f, CallInfo *ci) {
  int status = 1;
  if (f == NULL) {
    info_tailcall(ar);
    return status;
  }
  for (; *what; what++) {
    switch (*what) {
      case 'S': {
        funcinfo(ar, f);
        break;
      }
      case 'l': {
        ar->currentline = (ci) ? currentline(L, ci) : -1;
        break;
      }
      case 'u': {
        ar->nups = f->c.nupvalues;
        break;
      }
      case 'n': {
        ar->namewhat = (ci) ? getfuncname(L, ci, &ar->name) : NULL;
        if (ar->namewhat == NULL) {
          ar->namewhat = "";  /* not found */
          ar->name = NULL;
        }
        break;
      }
      case 'L':
      case 'f':  /* handled by lua_getinfo */
        break;
      default: status = 0;  /* invalid option */
    }
  }
  return status;
}


LUA_API int lua_getinfo (lua_State *L, const char *what, lua_Debug *ar) {
  int status;
  Closure *f = NULL;
  CallInfo *ci = NULL;
  lua_lock(L);
  if (*what == '>') {
    StkId func = L->top - 1;
    luai_apicheck(L, ttisfunction(func));
    what++;  /* skip the '>' */
    f = clvalue(func);
    L->top--;  /* pop function */
  }
  else if (ar->i_ci != 0) {  /* no tail call? */
    ci = L->base_ci + ar->i_ci;
    lua_assert(ttisfunction(ci->func));
    f = clvalue(ci->func);
  }
  status = auxgetinfo(L, what, ar, f, ci);
  if (strchr(what, 'f')) {
    if (f == NULL) setnilvalue(L->top);
    else setclvalue(L, L->top, f);
    incr_top(L);
  }
  if (strchr(what, 'L'))
    collectvalidlines(L, f);
  lua_unlock(L);
  return status;
}


/*
** {======================================================
** Symbolic Execution and code checker
** =======================================================
*/

#define check(x)		if (!(x)) return 0;

#define checkjump(pt,pc)	check(0 <= pc && pc < pt->sizecode)

#define checkreg(pt,reg)	check((reg) < (pt)->maxstacksize)



static int precheck (const Proto *pt) {
  check(pt->maxstacksize <= MAXSTACK);
  check(pt->numparams+(pt->is_vararg & VARARG_HASARG) <= pt->maxstacksize);
  check(!(pt->is_vararg & VARARG_NEEDSARG) ||
              (pt->is_vararg & VARARG_HASARG));
  check(pt->sizeupvalues <= pt->nups);
#ifndef LUA_OPTIMIZE_DEBUG
  check(pt->sizelineinfo == pt->sizecode || pt->sizelineinfo == 0);
#endif
  check(pt->sizecode > 0 && GET_OPCODE(pt->code[pt->sizecode-1]) == OP_RETURN);
  return 1;
}


#define checkopenop(pt,pc)	luaG_checkopenop((pt)->code[(pc)+1])

int luaG_checkopenop (Instruction i) {
  switch (GET_OPCODE(i)) {
    case OP_CALL:
    case OP_TAILCALL:
    case OP_RETURN:
    case OP_SETLIST: {
      check(GETARG_B(i) == 0);
      return 1;
    }
    default: return 0;  /* invalid instruction after an open call */
  }
}


static int checkArgMode (const Proto *pt, int r, enum OpArgMask mode) {
  switch (mode) {
    case OpArgN: check(r == 0); break;
    case OpArgU: break;
    case OpArgR: checkreg(pt, r); break;
    case OpArgK:
      check(ISK(r) ? INDEXK(r) < pt->sizek : r < pt->maxstacksize);
      break;
  }
  return 1;
}


static Instruction symbexec (const Proto *pt, int lastpc, int reg) {
  int pc;
  int last;  /* stores position of last instruction that changed `reg' */
  last = pt->sizecode-1;  /* points to final return (a `neutral' instruction) */
  check(precheck(pt));
  for (pc = 0; pc < lastpc; pc++) {
    Instruction i = pt->code[pc];
    OpCode op = GET_OPCODE(i);
    int a = GETARG_A(i);
    int b = 0;
    int c = 0;
    check(op < NUM_OPCODES);
    checkreg(pt, a);
    switch (getOpMode(op)) {
      case iABC: {
        b = GETARG_B(i);
        c = GETARG_C(i);
        check(checkArgMode(pt, b, getBMode(op)));
        check(checkArgMode(pt, c, getCMode(op)));
        break;
      }
      case iABx: {
        b = GETARG_Bx(i);
        if (getBMode(op) == OpArgK) check(b < pt->sizek);
        break;
      }
      case iAsBx: {
        b = GETARG_sBx(i);
        if (getBMode(op) == OpArgR) {
          int dest = pc+1+b;
          check(0 <= dest && dest < pt->sizecode);
          if (dest > 0) {
            int j;
            /* check that it does not jump to a setlist count; this
               is tricky, because the count from a previous setlist may
               have the same value of an invalid setlist; so, we must
               go all the way back to the first of them (if any) */
            for (j = 0; j < dest; j++) {
              Instruction d = pt->code[dest-1-j];
              if (!(GET_OPCODE(d) == OP_SETLIST && GETARG_C(d) == 0)) break;
            }
            /* if 'j' is even, previous value is not a setlist (even if
               it looks like one) */
            check((j&1) == 0);
          }
        }
        break;
      }
    }
    if (testAMode(op)) {
      if (a == reg) last = pc;  /* change register `a' */
    }
    if (testTMode(op)) {
      check(pc+2 < pt->sizecode);  /* check skip */
      check(GET_OPCODE(pt->code[pc+1]) == OP_JMP);
    }
    switch (op) {
      case OP_LOADBOOL: {
        if (c == 1) {  /* does it jump? */
          check(pc+2 < pt->sizecode);  /* check its jump */
          check(GET_OPCODE(pt->code[pc+1]) != OP_SETLIST ||
                GETARG_C(pt->code[pc+1]) != 0);
        }
        break;
      }
      case OP_LOADNIL: {
        if (a <= reg && reg <= b)
          last = pc;  /* set registers from `a' to `b' */
        break;
      }
      case OP_GETUPVAL:
      case OP_SETUPVAL: {
        check(b < pt->nups);
        break;
      }
      case OP_GETGLOBAL:
      case OP_SETGLOBAL: {
        check(ttisstring(&pt->k[b]));
        break;
      }
      case OP_SELF: {
        checkreg(pt, a+1);
        if (reg == a+1) last = pc;
        break;
      }
      case OP_CONCAT: {
        check(b < c);  /* at least two operands */
        break;
      }
      case OP_TFORLOOP: {
        check(c >= 1);  /* at least one result (control variable) */
        checkreg(pt, a+2+c);  /* space for results */
        if (reg >= a+2) last = pc;  /* affect all regs above its base */
        break;
      }
      case OP_FORLOOP:
      case OP_FORPREP:
        checkreg(pt, a+3);
        /* go through */
      case OP_JMP: {
        int dest = pc+1+b;
        /* not full check and jump is forward and do not skip `lastpc'? */
        if (reg != NO_REG && pc < dest && dest <= lastpc)
          pc += b;  /* do the jump */
        break;
      }
      case OP_CALL:
      case OP_TAILCALL: {
        if (b != 0) {
          checkreg(pt, a+b-1);
        }
        c--;  /* c = num. returns */
        if (c == LUA_MULTRET) {
          check(checkopenop(pt, pc));
        }
        else if (c != 0)
          checkreg(pt, a+c-1);
        if (reg >= a) last = pc;  /* affect all registers above base */
        break;
      }
      case OP_RETURN: {
        b--;  /* b = num. returns */
        if (b > 0) checkreg(pt, a+b-1);
        break;
      }
      case OP_SETLIST: {
        if (b > 0) checkreg(pt, a + b);
        if (c == 0) {
          pc++;
          check(pc < pt->sizecode - 1);
        }
        break;
      }
      case OP_CLOSURE: {
        int nup, j;
        check(b < pt->sizep);
        nup = pt->p[b]->nups;
        check(pc + nup < pt->sizecode);
        for (j = 1; j <= nup; j++) {
          OpCode op1 = GET_OPCODE(pt->code[pc + j]);
          check(op1 == OP_GETUPVAL || op1 == OP_MOVE);
        }
        if (reg != NO_REG)  /* tracing? */
          pc += nup;  /* do not 'execute' these pseudo-instructions */
        break;
      }
      case OP_VARARG: {
        check((pt->is_vararg & VARARG_ISVARARG) &&
             !(pt->is_vararg & VARARG_NEEDSARG));
        b--;
        if (b == LUA_MULTRET) check(checkopenop(pt, pc));
        checkreg(pt, a+b-1);
        break;
      }
      default: break;
    }
  }
  return pt->code[last];
}

#undef check
#undef checkjump
#undef checkreg

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


int luaG_checkcode (const Proto *pt) {
  return (symbexec(pt, pt->sizecode, NO_REG) != 0);
}


static const char *kname (Proto *p, int c) {
  if (ISK(c) && ttisstring(&p->k[INDEXK(c)]))
    return svalue(&p->k[INDEXK(c)]);
  else
    return "?";
}


static const char *getobjname (lua_State *L, CallInfo *ci, int stackpos,
                               const char **name) {
  if (isLua(ci)) {  /* a Lua function? */
    Proto *p = ci_func(ci)->l.p;
    int pc = currentpc(L, ci);
    Instruction i;
    *name = luaF_getlocalname(p, stackpos+1, pc);
    if (*name)  /* is a local? */
      return "local";
    i = symbexec(p, pc, stackpos);  /* try symbolic execution */
    lua_assert(pc != -1);
    switch (GET_OPCODE(i)) {
      case OP_GETGLOBAL: {
        int g = GETARG_Bx(i);  /* global index */
        lua_assert(ttisstring(&p->k[g]));
        *name = svalue(&p->k[g]);
        return "global";
      }
      case OP_MOVE: {
        int a = GETARG_A(i);
        int b = GETARG_B(i);  /* move from `b' to `a' */
        if (b < a)
          return getobjname(L, ci, b, name);  /* get name for `b' */
        break;
      }
      case OP_GETTABLE: {
        int k = GETARG_C(i);  /* key index */
        *name = kname(p, k);
        return "field";
      }
      case OP_GETUPVAL: {
        int u = GETARG_B(i);  /* upvalue index */
        *name = p->upvalues ? getstr(p->upvalues[u]) : "?";
        return "upvalue";
      }
      case OP_SELF: {
        int k = GETARG_C(i);  /* key index */
        *name = kname(p, k);
        return "method";
      }
      default: break;
    }
  }
  return NULL;  /* no useful name found */
}


static const char *getfuncname (lua_State *L, CallInfo *ci, const char **name) {
  Instruction i;
  if ((isLua(ci) && ci->tailcalls > 0) || !isLua(ci - 1))
    return NULL;  /* calling function is not Lua (or is unknown) */
  ci--;  /* calling function */
  i = ci_func(ci)->l.p->code[currentpc(L, ci)];
  if (GET_OPCODE(i) == OP_CALL || GET_OPCODE(i) == OP_TAILCALL ||
      GET_OPCODE(i) == OP_TFORLOOP)
    return getobjname(L, ci, GETARG_A(i), name);
  else
    return NULL;  /* no useful name can be found */
}


/* only ANSI way to check whether a pointer points to an array */
static int isinstack (CallInfo *ci, const TValue *o) {
  StkId p;
  for (p = ci->base; p < ci->top; p++)
    if (o == p) return 1;
  return 0;
}


void luaG_typeerror (lua_State *L, const TValue *o, const char *op) {
  const char *name = NULL;
  const char *t = luaT_typenames[ttype(o)];
  const char *kind = (isinstack(L->ci, o)) ?
                         getobjname(L, L->ci, cast_int(o - L->base), &name) :
                         NULL;
  if (kind)
    luaG_runerror(L, "attempt to %s %s " LUA_QS " (a %s value)",
                op, kind, name, t);
  else
    luaG_runerror(L, "attempt to %s a %s value", op, t);
}


void luaG_concaterror (lua_State *L, StkId p1, StkId p2) {
  if (ttisstring(p1) || ttisnumber(p1)) p1 = p2;
  lua_assert(!ttisstring(p1) && !ttisnumber(p1));
  luaG_typeerror(L, p1, "concatenate");
}


void luaG_aritherror (lua_State *L, const TValue *p1, const TValue *p2) {
  TValue temp;
  if (luaV_tonumber(p1, &temp) == NULL)
    p2 = p1;  /* first operand is wrong */
  luaG_typeerror(L, p2, "perform arithmetic on");
}


int luaG_ordererror (lua_State *L, const TValue *p1, const TValue *p2) {
  const char *t1 = luaT_typenames[ttype(p1)];
  const char *t2 = luaT_typenames[ttype(p2)];
  if (t1[2] == t2[2])
    luaG_runerror(L, "attempt to compare two %s values", t1);
  else
    luaG_runerror(L, "attempt to compare %s with %s", t1, t2);
  return 0;
}


static void addinfo (lua_State *L, const char *msg) {
  CallInfo *ci = L->ci;
  if (isLua(ci)) {  /* is Lua code? */
    char buff[LUA_IDSIZE];  /* add file:line information */
    int line = currentline(L, ci);
    luaO_chunkid(buff, getstr(getluaproto(ci)->source), LUA_IDSIZE);
    luaO_pushfstring(L, "%s:%d: %s", buff, line, msg);
  }
}


void luaG_errormsg (lua_State *L) {
  if (L->errfunc != 0) {  /* is there an error handling function? */
    StkId errfunc = restorestack(L, L->errfunc);
    if (!ttisfunction(errfunc)) luaD_throw(L, LUA_ERRERR);
    setobjs2s(L, L->top, L->top - 1);  /* move argument */
    setobjs2s(L, L->top - 1, errfunc);  /* push function */
    incr_top(L);
    luaD_call(L, L->top - 2, 1);  /* call it */
  }
  luaD_throw(L, LUA_ERRRUN);
}


void luaG_runerror (lua_State *L, const char *fmt, ...) {
  va_list argp;
  va_start(argp, fmt);
  addinfo(L, luaO_pushvfstring(L, fmt, argp));
  va_end(argp);
  luaG_errormsg(L);
}