aboutsummaryrefslogtreecommitdiff
path: root/io/ftw.c
blob: 7104816e85a8e3d6675a2cd3c7239c979842d7b1 (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
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
/* File tree walker functions.
   Copyright (C) 1996-2020 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <https://www.gnu.org/licenses/>.  */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#if __GNUC__
# define alloca __builtin_alloca
#else
# if HAVE_ALLOCA_H
#  include <alloca.h>
# else
#  ifdef _AIX
 #  pragma alloca
#  else
char *alloca ();
#  endif
# endif
#endif

#ifdef _LIBC
# include <dirent.h>
# define NAMLEN(dirent) _D_EXACT_NAMLEN (dirent)
#else
# if HAVE_DIRENT_H
#  include <dirent.h>
#  define NAMLEN(dirent) strlen ((dirent)->d_name)
# else
#  define dirent direct
#  define NAMLEN(dirent) (dirent)->d_namlen
#  if HAVE_SYS_NDIR_H
#   include <sys/ndir.h>
#  endif
#  if HAVE_SYS_DIR_H
#   include <sys/dir.h>
#  endif
#  if HAVE_NDIR_H
#   include <ndir.h>
#  endif
# endif
#endif

#include <errno.h>
#include <fcntl.h>
#include <ftw.h>
#include <limits.h>
#include <search.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <not-cancel.h>
#include <sys/param.h>
#ifdef _LIBC
# include <include/sys/stat.h>
#else
# include <sys/stat.h>
#endif

#if ! _LIBC && !HAVE_DECL_STPCPY && !defined stpcpy
char *stpcpy ();
#endif

#if ! _LIBC && ! defined HAVE_MEMPCPY && ! defined mempcpy
/* Be CAREFUL that there are no side effects in N.  */
# define mempcpy(D, S, N) ((void *) ((char *) memcpy (D, S, N) + (N)))
#endif

/* #define NDEBUG 1 */
#include <assert.h>

#ifndef _LIBC
# undef __chdir
# define __chdir chdir
# undef __closedir
# define __closedir closedir
# undef __fchdir
# define __fchdir fchdir
# undef __getcwd
# define __getcwd(P, N) xgetcwd ()
extern char *xgetcwd (void);
# undef __mempcpy
# define __mempcpy mempcpy
# undef __opendir
# define __opendir opendir
# undef __readdir64
# define __readdir64 readdir
# undef __stpcpy
# define __stpcpy stpcpy
# undef __tdestroy
# define __tdestroy tdestroy
# undef __tfind
# define __tfind tfind
# undef __tsearch
# define __tsearch tsearch
# undef dirent64
# define dirent64 dirent
# undef MAX
# define MAX(a, b) ((a) > (b) ? (a) : (b))
#endif

/* Arrange to make lstat calls go through the wrapper function
   on systems with an lstat function that does not dereference symlinks
   that are specified with a trailing slash.  */
#if ! _LIBC && ! LSTAT_FOLLOWS_SLASHED_SYMLINK
int rpl_lstat (const char *, struct stat *);
# undef lstat
# define lstat(Name, Stat_buf) rpl_lstat(Name, Stat_buf)
#endif

#ifndef __set_errno
# define __set_errno(Val) errno = (Val)
#endif

/* Support for the LFS API version.  */
#ifndef FTW_NAME
# define FTW_NAME ftw
# define NFTW_NAME nftw
# define NFTW_OLD_NAME __old_nftw
# define NFTW_NEW_NAME __new_nftw
# define INO_T ino_t
# define STRUCT_STAT stat
# ifdef _LIBC
#  define LSTAT __lstat
#  define STAT __stat
#  define FSTATAT __fstatat
# else
#  define LSTAT lstat
#  define XTAT stat
#  define FSTATAT fstatat
# endif
# define FTW_FUNC_T __ftw_func_t
# define NFTW_FUNC_T __nftw_func_t
#endif

/* We define PATH_MAX if the system does not provide a definition.
   This does not artificially limit any operation.  PATH_MAX is simply
   used as a guesstimate for the expected maximal path length.
   Buffers will be enlarged if necessary.  */
#ifndef PATH_MAX
# define PATH_MAX 1024
#endif

struct dir_data
{
  DIR *stream;
  int streamfd;
  char *content;
};

struct known_object
{
  dev_t dev;
  INO_T ino;
};

struct ftw_data
{
  /* Array with pointers to open directory streams.  */
  struct dir_data **dirstreams;
  size_t actdir;
  size_t maxdir;

  /* Buffer containing name of currently processed object.  */
  char *dirbuf;
  size_t dirbufsize;

  /* Passed as fourth argument to `nftw' callback.  The `base' member
     tracks the content of the `dirbuf'.  */
  struct FTW ftw;

  /* Flags passed to `nftw' function.  0 for `ftw'.  */
  int flags;

  /* Conversion array for flag values.  It is the identity mapping for
     `nftw' calls, otherwise it maps the values to those known by
     `ftw'.  */
  const int *cvt_arr;

  /* Callback function.  We always use the `nftw' form.  */
  NFTW_FUNC_T func;

  /* Device of starting point.  Needed for FTW_MOUNT.  */
  dev_t dev;

  /* Data structure for keeping fingerprints of already processed
     object.  This is needed when not using FTW_PHYS.  */
  void *known_objects;
};


/* Internally we use the FTW_* constants used for `nftw'.  When invoked
   as `ftw', map each flag to the subset of values used by `ftw'.  */
static const int nftw_arr[] =
{
  FTW_F, FTW_D, FTW_DNR, FTW_NS, FTW_SL, FTW_DP, FTW_SLN
};

static const int ftw_arr[] =
{
  FTW_F, FTW_D, FTW_DNR, FTW_NS, FTW_F, FTW_D, FTW_NS
};


/* Forward declarations of local functions.  */
static int ftw_dir (struct ftw_data *data, struct STRUCT_STAT *st,
		    struct dir_data *old_dir);


static int
object_compare (const void *p1, const void *p2)
{
  /* We don't need a sophisticated and useful comparison.  We are only
     interested in equality.  However, we must be careful not to
     accidentally compare `holes' in the structure.  */
  const struct known_object *kp1 = p1, *kp2 = p2;
  int cmp1;
  cmp1 = (kp1->ino > kp2->ino) - (kp1->ino < kp2->ino);
  if (cmp1 != 0)
    return cmp1;
  return (kp1->dev > kp2->dev) - (kp1->dev < kp2->dev);
}


static int
add_object (struct ftw_data *data, struct STRUCT_STAT *st)
{
  struct known_object *newp = malloc (sizeof (struct known_object));
  if (newp == NULL)
    return -1;
  newp->dev = st->st_dev;
  newp->ino = st->st_ino;
  return __tsearch (newp, &data->known_objects, object_compare) ? 0 : -1;
}


static inline int
find_object (struct ftw_data *data, struct STRUCT_STAT *st)
{
  struct known_object obj;
  obj.dev = st->st_dev;
  obj.ino = st->st_ino;
  return __tfind (&obj, &data->known_objects, object_compare) != NULL;
}


static inline int
__attribute ((always_inline))
open_dir_stream (int *dfdp, struct ftw_data *data, struct dir_data *dirp)
{
  int result = 0;

  if (data->dirstreams[data->actdir] != NULL)
    {
      /* Oh, oh.  We must close this stream.  Get all remaining
	 entries and store them as a list in the `content' member of
	 the `struct dir_data' variable.  */
      size_t bufsize = 1024;
      char *buf = malloc (bufsize);

      if (buf == NULL)
	result = -1;
      else
	{
	  DIR *st = data->dirstreams[data->actdir]->stream;
	  struct dirent64 *d;
	  size_t actsize = 0;

	  while ((d = __readdir64 (st)) != NULL)
	    {
	      size_t this_len = NAMLEN (d);
	      if (actsize + this_len + 2 >= bufsize)
		{
		  char *newp;
		  bufsize += MAX (1024, 2 * this_len);
		  newp = (char *) realloc (buf, bufsize);
		  if (newp == NULL)
		    {
		      /* No more memory.  */
		      int save_err = errno;
		      free (buf);
		      __set_errno (save_err);
		      return -1;
		    }
		  buf = newp;
		}

	      *((char *) __mempcpy (buf + actsize, d->d_name, this_len))
		= '\0';
	      actsize += this_len + 1;
	    }

	  /* Terminate the list with an additional NUL byte.  */
	  buf[actsize++] = '\0';

	  /* Shrink the buffer to what we actually need.  */
	  data->dirstreams[data->actdir]->content = realloc (buf, actsize);
	  if (data->dirstreams[data->actdir]->content == NULL)
	    {
	      int save_err = errno;
	      free (buf);
	      __set_errno (save_err);
	      result = -1;
	    }
	  else
	    {
	      __closedir (st);
	      data->dirstreams[data->actdir]->stream = NULL;
	      data->dirstreams[data->actdir]->streamfd = -1;
	      data->dirstreams[data->actdir] = NULL;
	    }
	}
    }

  /* Open the new stream.  */
  if (result == 0)
    {
      assert (data->dirstreams[data->actdir] == NULL);

      if (dfdp != NULL && *dfdp != -1)
	{
	  int fd = __openat64_nocancel (*dfdp, data->dirbuf + data->ftw.base,
					O_RDONLY | O_DIRECTORY | O_NDELAY);
	  dirp->stream = NULL;
	  if (fd != -1 && (dirp->stream = __fdopendir (fd)) == NULL)
	    __close_nocancel_nostatus (fd);
	}
      else
	{
	  const char *name;

	  if (data->flags & FTW_CHDIR)
	    {
	      name = data->dirbuf + data->ftw.base;
	      if (name[0] == '\0')
		name = ".";
	    }
	  else
	    name = data->dirbuf;

	  dirp->stream = __opendir (name);
	}

      if (dirp->stream == NULL)
	result = -1;
      else
	{
	  dirp->streamfd = __dirfd (dirp->stream);
	  dirp->content = NULL;
	  data->dirstreams[data->actdir] = dirp;

	  if (++data->actdir == data->maxdir)
	    data->actdir = 0;
	}
    }

  return result;
}


static int
process_entry (struct ftw_data *data, struct dir_data *dir, const char *name,
	       size_t namlen, int d_type)
{
  struct STRUCT_STAT st;
  int result = 0;
  int flag = 0;
  size_t new_buflen;

  if (name[0] == '.' && (name[1] == '\0'
			 || (name[1] == '.' && name[2] == '\0')))
    /* Don't process the "." and ".." entries.  */
    return 0;

  new_buflen = data->ftw.base + namlen + 2;
  if (data->dirbufsize < new_buflen)
    {
      /* Enlarge the buffer.  */
      char *newp;

      data->dirbufsize = 2 * new_buflen;
      newp = (char *) realloc (data->dirbuf, data->dirbufsize);
      if (newp == NULL)
	return -1;
      data->dirbuf = newp;
    }

  *((char *) __mempcpy (data->dirbuf + data->ftw.base, name, namlen)) = '\0';

  int statres;
  if (dir->streamfd != -1)
    statres = FSTATAT (dir->streamfd, name, &st,
		       (data->flags & FTW_PHYS) ? AT_SYMLINK_NOFOLLOW : 0);
  else
    {
      if ((data->flags & FTW_CHDIR) == 0)
	name = data->dirbuf;

      statres = ((data->flags & FTW_PHYS)
		 ? LSTAT (name, &st)
		 : STAT (name, &st));
    }

  if (statres < 0)
    {
      if (errno != EACCES && errno != ENOENT)
	result = -1;
      else if (data->flags & FTW_PHYS)
	flag = FTW_NS;
      else
	{
	  /* Old code left ST undefined for dangling DT_LNK without
	     FTW_PHYS set; a clarification at the POSIX level suggests
	     it should contain information about the link (ala lstat).
	     We do our best to fill in what data we can.  */
	  if (dir->streamfd != -1)
	    statres = FSTATAT (dir->streamfd, name, &st,
			       AT_SYMLINK_NOFOLLOW);
	  else
	    statres = LSTAT (name, &st);
	  if (statres == 0 && S_ISLNK (st.st_mode))
	    flag = FTW_SLN;
	  else
	    flag = FTW_NS;
	}
    }
  else
    {
      if (S_ISDIR (st.st_mode))
	flag = FTW_D;
      else if (S_ISLNK (st.st_mode))
	flag = FTW_SL;
      else
	flag = FTW_F;
    }

  if (result == 0
      && (flag == FTW_NS
	  || !(data->flags & FTW_MOUNT) || st.st_dev == data->dev))
    {
      if (flag == FTW_D)
	{
	  if ((data->flags & FTW_PHYS)
	      || (!find_object (data, &st)
		  /* Remember the object.  */
		  && (result = add_object (data, &st)) == 0))
	    result = ftw_dir (data, &st, dir);
	}
      else
	result = (*data->func) (data->dirbuf, &st, data->cvt_arr[flag],
				&data->ftw);
    }

  if ((data->flags & FTW_ACTIONRETVAL) && result == FTW_SKIP_SUBTREE)
    result = 0;

  return result;
}


static int
__attribute ((noinline))
ftw_dir (struct ftw_data *data, struct STRUCT_STAT *st, struct dir_data *old_dir)
{
  struct dir_data dir;
  struct dirent64 *d;
  int previous_base = data->ftw.base;
  int result;
  char *startp;

  /* Open the stream for this directory.  This might require that
     another stream has to be closed.  */
  result = open_dir_stream (old_dir == NULL ? NULL : &old_dir->streamfd,
			    data, &dir);
  if (result != 0)
    {
      if (errno == EACCES)
	/* We cannot read the directory.  Signal this with a special flag.  */
	result = (*data->func) (data->dirbuf, st, FTW_DNR, &data->ftw);

      return result;
    }

  /* First, report the directory (if not depth-first).  */
  if (!(data->flags & FTW_DEPTH))
    {
      result = (*data->func) (data->dirbuf, st, FTW_D, &data->ftw);
      if (result != 0)
	{
	  int save_err;
fail:
	  save_err = errno;
	  __closedir (dir.stream);
	  dir.streamfd = -1;
	  __set_errno (save_err);

	  if (data->actdir-- == 0)
	    data->actdir = data->maxdir - 1;
	  data->dirstreams[data->actdir] = NULL;
	  return result;
	}
    }

  /* If necessary, change to this directory.  */
  if (data->flags & FTW_CHDIR)
    {
      if (__fchdir (__dirfd (dir.stream)) < 0)
	{
	  result = -1;
	  goto fail;
	}
    }

  /* Next, update the `struct FTW' information.  */
  ++data->ftw.level;
  startp = __rawmemchr (data->dirbuf, '\0');
  /* There always must be a directory name.  */
  assert (startp != data->dirbuf);
  if (startp[-1] != '/')
    *startp++ = '/';
  data->ftw.base = startp - data->dirbuf;

  while (dir.stream != NULL && (d = __readdir64 (dir.stream)) != NULL)
    {
      int d_type = DT_UNKNOWN;
#ifdef _DIRENT_HAVE_D_TYPE
      d_type = d->d_type;
#endif
      result = process_entry (data, &dir, d->d_name, NAMLEN (d), d_type);
      if (result != 0)
	break;
    }

  if (dir.stream != NULL)
    {
      /* The stream is still open.  I.e., we did not need more
	 descriptors.  Simply close the stream now.  */
      int save_err = errno;

      assert (dir.content == NULL);

      __closedir (dir.stream);
      dir.streamfd = -1;
      __set_errno (save_err);

      if (data->actdir-- == 0)
	data->actdir = data->maxdir - 1;
      data->dirstreams[data->actdir] = NULL;
    }
  else
    {
      int save_err;
      char *runp = dir.content;

      while (result == 0 && *runp != '\0')
	{
	  char *endp = strchr (runp, '\0');

	  // XXX Should store the d_type values as well?!
	  result = process_entry (data, &dir, runp, endp - runp, DT_UNKNOWN);

	  runp = endp + 1;
	}

      save_err = errno;
      free (dir.content);
      __set_errno (save_err);
    }

  if ((data->flags & FTW_ACTIONRETVAL) && result == FTW_SKIP_SIBLINGS)
    result = 0;

  /* Prepare the return, revert the `struct FTW' information.  */
  data->dirbuf[data->ftw.base - 1] = '\0';
  --data->ftw.level;
  data->ftw.base = previous_base;

  /* Finally, if we process depth-first report the directory.  */
  if (result == 0 && (data->flags & FTW_DEPTH))
    result = (*data->func) (data->dirbuf, st, FTW_DP, &data->ftw);

  if (old_dir
      && (data->flags & FTW_CHDIR)
      && (result == 0
	  || ((data->flags & FTW_ACTIONRETVAL)
	      && (result != -1 && result != FTW_STOP))))
    {
      /* Change back to the parent directory.  */
      int done = 0;
      if (old_dir->stream != NULL)
	if (__fchdir (__dirfd (old_dir->stream)) == 0)
	  done = 1;

      if (!done)
	{
	  if (data->ftw.base == 1)
	    {
	      if (__chdir ("/") < 0)
		result = -1;
	    }
	  else
	    if (__chdir ("..") < 0)
	      result = -1;
	}
    }

  return result;
}


static int
__attribute ((noinline))
ftw_startup (const char *dir, int is_nftw, void *func, int descriptors,
	     int flags)
{
  struct ftw_data data;
  struct STRUCT_STAT st;
  int result = 0;
  int save_err;
  int cwdfd = -1;
  char *cwd = NULL;
  char *cp;

  /* First make sure the parameters are reasonable.  */
  if (dir[0] == '\0')
    {
      __set_errno (ENOENT);
      return -1;
    }

  data.maxdir = descriptors < 1 ? 1 : descriptors;
  data.actdir = 0;
  data.dirstreams = (struct dir_data **) alloca (data.maxdir
						 * sizeof (struct dir_data *));
  memset (data.dirstreams, '\0', data.maxdir * sizeof (struct dir_data *));

  /* PATH_MAX is always defined when we get here.  */
  data.dirbufsize = MAX (2 * strlen (dir), PATH_MAX);
  data.dirbuf = (char *) malloc (data.dirbufsize);
  if (data.dirbuf == NULL)
    return -1;
  cp = __stpcpy (data.dirbuf, dir);
  /* Strip trailing slashes.  */
  while (cp > data.dirbuf + 1 && cp[-1] == '/')
    --cp;
  *cp = '\0';

  data.ftw.level = 0;

  /* Find basename.  */
  while (cp > data.dirbuf && cp[-1] != '/')
    --cp;
  data.ftw.base = cp - data.dirbuf;

  data.flags = flags;

  /* This assignment might seem to be strange but it is what we want.
     The trick is that the first three arguments to the `ftw' and
     `nftw' callback functions are equal.  Therefore we can call in
     every case the callback using the format of the `nftw' version
     and get the correct result since the stack layout for a function
     call in C allows this.  */
  data.func = (NFTW_FUNC_T) func;

  /* Since we internally use the complete set of FTW_* values we need
     to reduce the value range before calling a `ftw' callback.  */
  data.cvt_arr = is_nftw ? nftw_arr : ftw_arr;

  /* No object known so far.  */
  data.known_objects = NULL;

  /* Now go to the directory containing the initial file/directory.  */
  if (flags & FTW_CHDIR)
    {
      /* We have to be able to go back to the current working
	 directory.  The best way to do this is to use a file
	 descriptor.  */
      cwdfd = __open (".", O_RDONLY | O_DIRECTORY);
      if (cwdfd == -1)
	{
	  /* Try getting the directory name.  This can be needed if
	     the current directory is executable but not readable.  */
	  if (errno == EACCES)
	    /* GNU extension ahead.  */
	    cwd =  __getcwd (NULL, 0);

	  if (cwd == NULL)
	    goto out_fail;
	}
      else if (data.maxdir > 1)
	/* Account for the file descriptor we use here.  */
	--data.maxdir;

      if (data.ftw.base > 0)
	{
	  /* Change to the directory the file is in.  In data.dirbuf
	     we have a writable copy of the file name.  Just NUL
	     terminate it for now and change the directory.  */
	  if (data.ftw.base == 1)
	    /* I.e., the file is in the root directory.  */
	    result = __chdir ("/");
	  else
	    {
	      char ch = data.dirbuf[data.ftw.base - 1];
	      data.dirbuf[data.ftw.base - 1] = '\0';
	      result = __chdir (data.dirbuf);
	      data.dirbuf[data.ftw.base - 1] = ch;
	    }
	}
    }

  /* Get stat info for start directory.  */
  if (result == 0)
    {
      const char *name;

      if (data.flags & FTW_CHDIR)
	{
	  name = data.dirbuf + data.ftw.base;
	  if (name[0] == '\0')
	    name = ".";
	}
      else
	name = data.dirbuf;

      if (((flags & FTW_PHYS)
	   ? LSTAT (name, &st)
	   : STAT (name, &st)) < 0)
	{
	  if (!(flags & FTW_PHYS)
	      && errno == ENOENT
	      && LSTAT (name, &st) == 0
	      && S_ISLNK (st.st_mode))
	    result = (*data.func) (data.dirbuf, &st, data.cvt_arr[FTW_SLN],
				   &data.ftw);
	  else
	    /* No need to call the callback since we cannot say anything
	       about the object.  */
	    result = -1;
	}
      else
	{
	  if (S_ISDIR (st.st_mode))
	    {
	      /* Remember the device of the initial directory in case
		 FTW_MOUNT is given.  */
	      data.dev = st.st_dev;

	      /* We know this directory now.  */
	      if (!(flags & FTW_PHYS))
		result = add_object (&data, &st);

	      if (result == 0)
		result = ftw_dir (&data, &st, NULL);
	    }
	  else
	    {
	      int flag = S_ISLNK (st.st_mode) ? FTW_SL : FTW_F;

	      result = (*data.func) (data.dirbuf, &st, data.cvt_arr[flag],
				     &data.ftw);
	    }
	}

      if ((flags & FTW_ACTIONRETVAL)
	  && (result == FTW_SKIP_SUBTREE || result == FTW_SKIP_SIBLINGS))
	result = 0;
    }

  /* Return to the start directory (if necessary).  */
  if (cwdfd != -1)
    {
      int save_err = errno;
      __fchdir (cwdfd);
      __close_nocancel_nostatus (cwdfd);
      __set_errno (save_err);
    }
  else if (cwd != NULL)
    {
      int save_err = errno;
      __chdir (cwd);
      free (cwd);
      __set_errno (save_err);
    }

  /* Free all memory.  */
 out_fail:
  save_err = errno;
  __tdestroy (data.known_objects, free);
  free (data.dirbuf);
  __set_errno (save_err);

  return result;
}



/* Entry points.  */

int
FTW_NAME (const char *path, FTW_FUNC_T func, int descriptors)
{
  return ftw_startup (path, 0, func, descriptors, 0);
}

#ifndef _LIBC
int
NFTW_NAME (const char *path, NFTW_FUNC_T func, int descriptors, int flags)
{
  return ftw_startup (path, 1, func, descriptors, flags);
}
#else

# include <shlib-compat.h>

int NFTW_NEW_NAME (const char *, NFTW_FUNC_T, int, int);

int
NFTW_NEW_NAME (const char *path, NFTW_FUNC_T func, int descriptors, int flags)
{
  if (flags
      & ~(FTW_PHYS | FTW_MOUNT | FTW_CHDIR | FTW_DEPTH | FTW_ACTIONRETVAL))
    {
      __set_errno (EINVAL);
      return -1;
    }
  return ftw_startup (path, 1, func, descriptors, flags);
}

versioned_symbol (libc, NFTW_NEW_NAME, NFTW_NAME, GLIBC_2_3_3);

# if SHLIB_COMPAT(libc, GLIBC_2_1, GLIBC_2_3_3)

/* Older nftw* version just ignored all unknown flags.  */

int NFTW_OLD_NAME (const char *, NFTW_FUNC_T, int, int);

int
attribute_compat_text_section
NFTW_OLD_NAME (const char *path, NFTW_FUNC_T func, int descriptors, int flags)
{
  flags &= (FTW_PHYS | FTW_MOUNT | FTW_CHDIR | FTW_DEPTH);
  return ftw_startup (path, 1, func, descriptors, flags);
}

compat_symbol (libc, NFTW_OLD_NAME, NFTW_NAME, GLIBC_2_1);
# endif
#endif