aboutsummaryrefslogtreecommitdiffstats
path: root/bruiser/lua-5.3.4/src/ldebug.c
blob: 239affb76c52842d4786a5eb1d445285ddcf9f0c (plain) (blame)
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
/*
** $Id: ldebug.c,v 2.121 2016/10/19 12:32:10 roberto Exp $
** Debug Interface
** See Copyright Notice in lua.h
*/

#define ldebug_c
#define LUA_CORE

#include "lprefix.h"


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

#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"



#define noLuaClosure(f)		((f) == NULL || (f)->c.tt == LUA_TCCL)


/* Active Lua function (given call info) */
#define ci_func(ci)		(clLvalue((ci)->func))


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


static int currentpc (CallInfo *ci) {
  lua_assert(isLua(ci));
  return pcRel(ci->u.l.savedpc, ci_func(ci)->p);
}


static int currentline (CallInfo *ci) {
  return getfuncline(ci_func(ci)->p, currentpc(ci));
}


/*
** If function yielded, its 'func' can be in the 'extra' field. The
** next function restores 'func' to its correct value for debugging
** purposes. (It exchanges 'func' and 'extra'; so, when called again,
** after debugging, it also "re-restores" ** 'func' to its altered value.
*/
static void swapextra (lua_State *L) {
  if (L->status == LUA_YIELD) {
    CallInfo *ci = L->ci;  /* get function that yielded */
    StkId temp = ci->func;  /* exchange its 'func' and 'extra' values */
    ci->func = restorestack(L, ci->extra);
    ci->extra = savestack(L, temp);
  }
}


/*
** This function can be called asynchronously (e.g. during a signal).
** Fields 'oldpc', 'basehookcount', and 'hookcount' (set by
** 'resethookcount') are for debug only, and it is no problem if they
** get arbitrary values (causes at most one wrong hook call). 'hookmask'
** is an atomic value. We assume that pointers are atomic too (e.g., gcc
** ensures that for all platforms where it runs). Moreover, 'hook' is
** always checked before being called (see 'luaD_hook').
*/
LUA_API void lua_sethook (lua_State *L, lua_Hook func, int mask, int count) {
  if (func == NULL || mask == 0) {  /* turn off hooks? */
    mask = 0;
    func = NULL;
  }
  if (isLua(L->ci))
    L->oldpc = L->ci->u.l.savedpc;
  L->hook = func;
  L->basehookcount = count;
  resethookcount(L);
  L->hookmask = cast_byte(mask);
}


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;
  if (level < 0) return 0;  /* invalid (negative) level */
  lua_lock(L);
  for (ci = L->ci; level > 0 && ci != &L->base_ci; ci = ci->previous)
    level--;
  if (level == 0 && ci != &L->base_ci) {  /* level found? */
    status = 1;
    ar->i_ci = ci;
  }
  else status = 0;  /* no such level */
  lua_unlock(L);
  return status;
}


static const char *upvalname (Proto *p, int uv) {
  TString *s = check_exp(uv < p->sizeupvalues, p->upvalues[uv].name);
  if (s == NULL) return "?";
  else return getstr(s);
}


static const char *findvararg (CallInfo *ci, int n, StkId *pos) {
  int nparams = clLvalue(ci->func)->p->numparams;
  if (n >= cast_int(ci->u.l.base - ci->func) - nparams)
    return NULL;  /* no such vararg */
  else {
    *pos = ci->func + nparams + n;
    return "(*vararg)";  /* generic name for any vararg */
  }
}


static const char *findlocal (lua_State *L, CallInfo *ci, int n,
                              StkId *pos) {
  const char *name = NULL;
  StkId base;
  if (isLua(ci)) {
    if (n < 0)  /* access to vararg values? */
      return findvararg(ci, -n, pos);
    else {
      base = ci->u.l.base;
      name = luaF_getlocalname(ci_func(ci)->p, n, currentpc(ci));
    }
  }
  else
    base = ci->func + 1;
  if (name == NULL) {  /* no 'standard' name? */
    StkId limit = (ci == L->ci) ? L->top : ci->next->func;
    if (limit - base >= n && n > 0)  /* is 'n' inside 'ci' stack? */
      name = "(*temporary)";  /* generic name for any valid slot */
    else
      return NULL;  /* no name */
  }
  *pos = base + (n - 1);
  return name;
}


LUA_API const char *lua_getlocal (lua_State *L, const lua_Debug *ar, int n) {
  const char *name;
  lua_lock(L);
  swapextra(L);
  if (ar == NULL) {  /* information about non-active function? */
    if (!isLfunction(L->top - 1))  /* not a Lua function? */
      name = NULL;
    else  /* consider live variables at function start (parameters) */
      name = luaF_getlocalname(clLvalue(L->top - 1)->p, n, 0);
  }
  else {  /* active function; get information through 'ar' */
    StkId pos = NULL;  /* to avoid warnings */
    name = findlocal(L, ar->i_ci, n, &pos);
    if (name) {
      setobj2s(L, L->top, pos);
      api_incr_top(L);
    }
  }
  swapextra(L);
  lua_unlock(L);
  return name;
}


LUA_API const char *lua_setlocal (lua_State *L, const lua_Debug *ar, int n) {
  StkId pos = NULL;  /* to avoid warnings */
  const char *name;
  lua_lock(L);
  swapextra(L);
  name = findlocal(L, ar->i_ci, n, &pos);
  if (name) {
    setobjs2s(L, pos, L->top - 1);
    L->top--;  /* pop value */
  }
  swapextra(L);
  lua_unlock(L);
  return name;
}


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


static void collectvalidlines (lua_State *L, Closure *f) {
  if (noLuaClosure(f)) {
    setnilvalue(L->top);
    api_incr_top(L);
  }
  else {
    int i;
    TValue v;
    int *lineinfo = f->l.p->lineinfo;
    Table *t = luaH_new(L);  /* new table to store active lines */
    sethvalue(L, L->top, t);  /* push it on stack */
    api_incr_top(L);
    setbvalue(&v, 1);  /* boolean 'true' to be the value of all indices */
    for (i = 0; i < f->l.p->sizelineinfo; i++)  /* for all lines with code */
      luaH_setint(L, t, lineinfo[i], &v);  /* table[line] = true */
  }
}


static const char *getfuncname (lua_State *L, CallInfo *ci, const char **name) {
  if (ci == NULL)  /* no 'ci'? */
    return NULL;  /* no info */
  else if (ci->callstatus & CIST_FIN) {  /* is this a finalizer? */
    *name = "__gc";
    return "metamethod";  /* report it as such */
  }
  /* calling function is a known Lua function? */
  else if (!(ci->callstatus & CIST_TAIL) && isLua(ci->previous))
    return funcnamefromcode(L, ci->previous, name);
  else return NULL;  /* no way to find a name */
}


static int auxgetinfo (lua_State *L, const char *what, lua_Debug *ar,
                       Closure *f, CallInfo *ci) {
  int status = 1;
  for (; *what; what++) {
    switch (*what) {
      case 'S': {
        funcinfo(ar, f);
        break;
      }
      case 'l': {
        ar->currentline = (ci && isLua(ci)) ? currentline(ci) : -1;
        break;
      }
      case 'u': {
        ar->nups = (f == NULL) ? 0 : f->c.nupvalues;
        if (noLuaClosure(f)) {
          ar->isvararg = 1;
          ar->nparams = 0;
        }
        else {
          ar->isvararg = f->l.p->is_vararg;
          ar->nparams = f->l.p->numparams;
        }
        break;
      }
      case 't': {
        ar->istailcall = (ci) ? ci->callstatus & CIST_TAIL : 0;
        break;
      }
      case 'n': {
        ar->namewhat = getfuncname(L, ci, &ar->name);
        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 *cl;
  CallInfo *ci;
  StkId func;
  lua_lock(L);
  swapextra(L);
  if (*what == '>') {
    ci = NULL;
    func = L->top - 1;
    api_check(L, ttisfunction(func), "function expected");
    what++;  /* skip the '>' */
    L->top--;  /* pop function */
  }
  else {
    ci = ar->i_ci;
    func = ci->func;
    lua_assert(ttisfunction(ci->func));
  }
  cl = ttisclosure(func) ? clvalue(func) : NULL;
  status = auxgetinfo(L, what, ar, cl, ci);
  if (strchr(what, 'f')) {
    setobjs2s(L, L->top, func);
    api_incr_top(L);
  }
  swapextra(L);  /* correct before option 'L', which can raise a mem. error */
  if (strchr(what, 'L'))
    collectvalidlines(L, cl);
  lua_unlock(L);
  return status;
}


/*
** {======================================================
** Symbolic Execution
** =======================================================
*/

static const char *getobjname (Proto *p, int lastpc, int reg,
                               const char **name);


/*
** find a "name" for the RK value 'c'
*/
static void kname (Proto *p, int pc, int c, const char **name) {
  if (ISK(c)) {  /* is 'c' a constant? */
    TValue *kvalue = &p->k[INDEXK(c)];
    if (ttisstring(kvalue)) {  /* literal constant? */
      *name = svalue(kvalue);  /* it is its own name */
      return;
    }
    /* else no reasonable name found */
  }
  else {  /* 'c' is a register */
    const char *what = getobjname(p, pc, c, name); /* search for 'c' */
    if (what && *what == 'c') {  /* found a constant name? */
      return;  /* 'name' already filled */
    }
    /* else no reasonable name found */
  }
  *name = "?";  /* no reasonable name found */
}


static int filterpc (int pc, int jmptarget) {
  if (pc < jmptarget)  /* is code conditional (inside a jump)? */
    return -1;  /* cannot know who sets that register */
  else return pc;  /* current position sets that register */
}


/*
** try to find last instruction before 'lastpc' that modified register 'reg'
*/
static int findsetreg (Proto *p, int lastpc, int reg) {
  int pc;
  int setreg = -1;  /* keep last instruction that changed 'reg' */
  int jmptarget = 0;  /* any code before this address is conditional */
  for (pc = 0; pc < lastpc; pc++) {
    Instruction i = p->code[pc];
    OpCode op = GET_OPCODE(i);
    int a = GETARG_A(i);
    switch (op) {
      case OP_LOADNIL: {
        int b = GETARG_B(i);
        if (a <= reg && reg <= a + b)  /* set registers from 'a' to 'a+b' */
          setreg = filterpc(pc, jmptarget);
        break;
      }
      case OP_TFORCALL: {
        if (reg >= a + 2)  /* affect all regs above its base */
          setreg = filterpc(pc, jmptarget);
        break;
      }
      case OP_CALL:
      case OP_TAILCALL: {
        if (reg >= a)  /* affect all registers above base */
          setreg = filterpc(pc, jmptarget);
        break;
      }
      case OP_JMP: {
        int b = GETARG_sBx(i);
        int dest = pc + 1 + b;
        /* jump is forward and do not skip 'lastpc'? */
        if (pc < dest && dest <= lastpc) {
          if (dest > jmptarget)
            jmptarget = dest;  /* update 'jmptarget' */
        }
        break;
      }
      default:
        if (testAMode(op) && reg == a)  /* any instruction that set A */
          setreg = filterpc(pc, jmptarget);
        break;
    }
  }
  return setreg;
}


static const char *getobjname (Proto *p, int lastpc, int reg,
                               const char **name) {
  int pc;
  *name = luaF_getlocalname(p, reg + 1, lastpc);
  if (*name)  /* is a local? */
    return "local";
  /* else try symbolic execution */
  pc = findsetreg(p, lastpc, reg);
  if (pc != -1) {  /* could find instruction? */
    Instruction i = p->code[pc];
    OpCode op = GET_OPCODE(i);
    switch (op) {
      case OP_MOVE: {
        int b = GETARG_B(i);  /* move from 'b' to 'a' */
        if (b < GETARG_A(i))
          return getobjname(p, pc, b, name);  /* get name for 'b' */
        break;
      }
      case OP_GETTABUP:
      case OP_GETTABLE: {
        int k = GETARG_C(i);  /* key index */
        int t = GETARG_B(i);  /* table index */
        const char *vn = (op == OP_GETTABLE)  /* name of indexed variable */
                         ? luaF_getlocalname(p, t + 1, pc)
                         : upvalname(p, t);
        kname(p, pc, k, name);
        return (vn && strcmp(vn, LUA_ENV) == 0) ? "global" : "field";
      }
      case OP_GETUPVAL: {
        *name = upvalname(p, GETARG_B(i));
        return "upvalue";
      }
      case OP_LOADK:
      case OP_LOADKX: {
        int b = (op == OP_LOADK) ? GETARG_Bx(i)
                                 : GETARG_Ax(p->code[pc + 1]);
        if (ttisstring(&p->k[b])) {
          *name = svalue(&p->k[b]);
          return "constant";
        }
        break;
      }
      case OP_SELF: {
        int k = GETARG_C(i);  /* key index */
        kname(p, pc, k, name);
        return "method";
      }
      default: break;  /* go through to return NULL */
    }
  }
  return NULL;  /* could not find reasonable name */
}


/*
** Try to find a name for a function based on the code that called it.
** (Only works when function was called by a Lua function.)
** Returns what the name is (e.g., "for iterator", "method",
** "metamethod") and sets '*name' to point to the name.
*/
static const char *funcnamefromcode (lua_State *L, CallInfo *ci,
                                     const char **name) {
  TMS tm = (TMS)0;  /* (initial value avoids warnings) */
  Proto *p = ci_func(ci)->p;  /* calling function */
  int pc = currentpc(ci);  /* calling instruction index */
  Instruction i = p->code[pc];  /* calling instruction */
  if (ci->callstatus & CIST_HOOKED) {  /* was it called inside a hook? */
    *name = "?";
    return "hook";
  }
  switch (GET_OPCODE(i)) {
    case OP_CALL:
    case OP_TAILCALL:
      return getobjname(p, pc, GETARG_A(i), name);  /* get function name */
    case OP_TFORCALL: {  /* for iterator */
      *name = "for iterator";
       return "for iterator";
    }
    /* other instructions can do calls through metamethods */
    case OP_SELF: case OP_GETTABUP: case OP_GETTABLE:
      tm = TM_INDEX;
      break;
    case OP_SETTABUP: case OP_SETTABLE:
      tm = TM_NEWINDEX;
      break;
    case OP_ADD: case OP_SUB: case OP_MUL: case OP_MOD:
    case OP_POW: case OP_DIV: case OP_IDIV: case OP_BAND:
    case OP_BOR: case OP_BXOR: case OP_SHL: case OP_SHR: {
      int offset = cast_int(GET_OPCODE(i)) - cast_int(OP_ADD);  /* ORDER OP */
      tm = cast(TMS, offset + cast_int(TM_ADD));  /* ORDER TM */
      break;
    }
    case OP_UNM: tm = TM_UNM; break;
    case OP_BNOT: tm = TM_BNOT; break;
    case OP_LEN: tm = TM_LEN; break;
    case OP_CONCAT: tm = TM_CONCAT; break;
    case OP_EQ: tm = TM_EQ; break;
    case OP_LT: tm = TM_LT; break;
    case OP_LE: tm = TM_LE; break;
    default:
      return NULL;  /* cannot find a reasonable name */
  }
  *name = getstr(G(L)->tmname[tm]);
  return "metamethod";
}

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



/*
** The subtraction of two potentially unrelated pointers is
** not ISO C, but it should not crash a program; the subsequent
** checks are ISO C and ensure a correct result.
*/
static int isinstack (CallInfo *ci, const TValue *o) {
  ptrdiff_t i = o - ci->u.l.base;
  return (0 <= i && i < (ci->top - ci->u.l.base) && ci->u.l.base + i == o);
}


/*
** Checks whether value 'o' came from an upvalue. (That can only happen
** with instructions OP_GETTABUP/OP_SETTABUP, which operate directly on
** upvalues.)
*/
static const char *getupvalname (CallInfo *ci, const TValue *o,
                                 const char **name) {
  LClosure *c = ci_func(ci);
  int i;
  for (i = 0; i < c->nupvalues; i++) {
    if (c->upvals[i]->v == o) {
      *name = upvalname(c->p, i);
      return "upvalue";
    }
  }
  return NULL;
}


static const char *varinfo (lua_State *L, const TValue *o) {
  const char *name = NULL;  /* to avoid warnings */
  CallInfo *ci = L->ci;
  const char *kind = NULL;
  if (isLua(ci)) {
    kind = getupvalname(ci, o, &name);  /* check whether 'o' is an upvalue */
    if (!kind && isinstack(ci, o))  /* no? try a register */
      kind = getobjname(ci_func(ci)->p, currentpc(ci),
                        cast_int(o - ci->u.l.base), &name);
  }
  return (kind) ? luaO_pushfstring(L, " (%s '%s')", kind, name) : "";
}


l_noret luaG_typeerror (lua_State *L, const TValue *o, const char *op) {
  const char *t = luaT_objtypename(L, o);
  luaG_runerror(L, "attempt to %s a %s value%s", op, t, varinfo(L, o));
}


l_noret luaG_concaterror (lua_State *L, const TValue *p1, const TValue *p2) {
  if (ttisstring(p1) || cvt2str(p1)) p1 = p2;
  luaG_typeerror(L, p1, "concatenate");
}


l_noret luaG_opinterror (lua_State *L, const TValue *p1,
                         const TValue *p2, const char *msg) {
  lua_Number temp;
  if (!tonumber(p1, &temp))  /* first operand is wrong? */
    p2 = p1;  /* now second is wrong */
  luaG_typeerror(L, p2, msg);
}


/*
** Error when both values are convertible to numbers, but not to integers
*/
l_noret luaG_tointerror (lua_State *L, const TValue *p1, const TValue *p2) {
  lua_Integer temp;
  if (!tointeger(p1, &temp))
    p2 = p1;
  luaG_runerror(L, "number%s has no integer representation", varinfo(L, p2));
}


l_noret luaG_ordererror (lua_State *L, const TValue *p1, const TValue *p2) {
  const char *t1 = luaT_objtypename(L, p1);
  const char *t2 = luaT_objtypename(L, p2);
  if (strcmp(t1, t2) == 0)
    luaG_runerror(L, "attempt to compare two %s values", t1);
  else
    luaG_runerror(L, "attempt to compare %s with %s", t1, t2);
}


/* add src:line information to 'msg' */
const char *luaG_addinfo (lua_State *L, const char *msg, TString *src,
                                        int line) {
  char buff[LUA_IDSIZE];
  if (src)
    luaO_chunkid(buff, getstr(src), LUA_IDSIZE);
  else {  /* no source available; use "?" instead */
    buff[0] = '?'; buff[1] = '\0';
  }
  return luaO_pushfstring(L, "%s:%d: %s", buff, line, msg);
}


l_noret luaG_errormsg (lua_State *L) {
  if (L->errfunc != 0) {  /* is there an error handling function? */
    StkId errfunc = restorestack(L, L->errfunc);
    setobjs2s(L, L->top, L->top - 1);  /* move argument */
    setobjs2s(L, L->top - 1, errfunc);  /* push function */
    L->top++;  /* assume EXTRA_STACK */
    luaD_callnoyield(L, L->top - 2, 1);  /* call it */
  }
  luaD_throw(L, LUA_ERRRUN);
}


l_noret luaG_runerror (lua_State *L, const char *fmt, ...) {
  CallInfo *ci = L->ci;
  const char *msg;
  va_list argp;
  va_start(argp, fmt);
  msg = luaO_pushvfstring(L, fmt, argp);  /* format message */
  va_end(argp);
  if (isLua(ci))  /* if Lua function, add source:line information */
    luaG_addinfo(L, msg, ci_func(ci)->p->source, currentline(ci));
  luaG_errormsg(L);
}


void luaG_traceexec (lua_State *L) {
  CallInfo *ci = L->ci;
  lu_byte mask = L->hookmask;
  int counthook = (--L->hookcount == 0 && (mask & LUA_MASKCOUNT));
  if (counthook)
    resethookcount(L);  /* reset count */
  else if (!(mask & LUA_MASKLINE))
    return;  /* no line hook and count != 0; nothing to be done */
  if (ci->callstatus & CIST_HOOKYIELD) {  /* called hook last time? */
    ci->callstatus &= ~CIST_HOOKYIELD;  /* erase mark */
    return;  /* do not call hook again (VM yielded, so it did not move) */
  }
  if (counthook)
    luaD_hook(L, LUA_HOOKCOUNT, -1);  /* call count hook */
  if (mask & LUA_MASKLINE) {
    Proto *p = ci_func(ci)->p;
    int npc = pcRel(ci->u.l.savedpc, p);
    int newline = getfuncline(p, npc);
    if (npc == 0 ||  /* call linehook when enter a new function, */
        ci->u.l.savedpc <= L->oldpc ||  /* when jump back (loop), or when */
        newline != getfuncline(p, pcRel(L->oldpc, p)))  /* enter a new line */
      luaD_hook(L, LUA_HOOKLINE, newline);  /* call line hook */
  }
  L->oldpc = ci->u.l.savedpc;
  if (L->status == LUA_YIELD) {  /* did hook yield? */
    if (counthook)
      L->hookcount = 1;  /* undo decrement to zero */
    ci->u.l.savedpc--;  /* undo increment (resume will increment it again) */
    ci->callstatus |= CIST_HOOKYIELD;  /* mark that it yielded */
    ci->func = L->top - 1;  /* protect stack below results */
    luaD_throw(L, LUA_YIELD);
  }
}