aboutsummaryrefslogtreecommitdiff
path: root/sysdeps/unix/readdir_r.c
blob: 93727912c1709b8d4d9ddf7a246b8b0d5c2e6c22 (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
/* Copyright (C) 1991,92,93,94,95,96,97,98,99,2000,02,10
	Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   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, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#include <errno.h>
#include <limits.h>
#include <stddef.h>
#include <string.h>
#include <dirent.h>
#include <unistd.h>
#include <sys/types.h>
#include <assert.h>

#include <dirstream.h>

#ifndef __READDIR_R
# define __READDIR_R __readdir_r
# define __GETDENTS __getdents
# define DIRENT_TYPE struct dirent
# define __READDIR_R_ALIAS
#endif

/* Read a directory entry from DIRP.  */
int
__READDIR_R (DIR *dirp, DIRENT_TYPE *entry, DIRENT_TYPE **result)
{
  DIRENT_TYPE *dp;
  size_t reclen;
  const int saved_errno = errno;

  __libc_lock_lock (dirp->lock);

  do
    {
      if (dirp->offset >= dirp->size)
	{
	  /* We've emptied out our buffer.  Refill it.  */

	  size_t maxread;
	  ssize_t bytes;

#ifndef _DIRENT_HAVE_D_RECLEN
	  /* Fixed-size struct; must read one at a time (see below).  */
	  maxread = sizeof *dp;
#else
	  maxread = dirp->allocation;
#endif

	  bytes = __GETDENTS (dirp->fd, dirp->data, maxread);
	  if (bytes <= 0)
	    {
	      /* On some systems getdents fails with ENOENT when the
		 open directory has been rmdir'd already.  POSIX.1
		 requires that we treat this condition like normal EOF.  */
	      if (bytes < 0 && errno == ENOENT)
		{
		  bytes = 0;
		  __set_errno (saved_errno);
		}

	      dp = NULL;
	      /* Reclen != 0 signals that an error occurred.  */
	      reclen = bytes != 0;
	      break;
	    }
	  dirp->size = (size_t) bytes;

	  /* Reset the offset into the buffer.  */
	  dirp->offset = 0;
	}

      dp = (DIRENT_TYPE *) &dirp->data[dirp->offset];

#ifdef _DIRENT_HAVE_D_RECLEN
      reclen = dp->d_reclen;
#else
      /* The only version of `struct dirent*' that lacks `d_reclen'
	 is fixed-size.  */
      assert (sizeof dp->d_name > 1);
      reclen = sizeof *dp;
      /* The name is not terminated if it is the largest possible size.
	 Clobber the following byte to ensure proper null termination.  We
	 read just one entry at a time above so we know that byte will not
	 be used later.  */
      dp->d_name[sizeof dp->d_name] = '\0';
#endif

      dirp->offset += reclen;

#ifdef _DIRENT_HAVE_D_OFF
      dirp->filepos = dp->d_off;
#else
      dirp->filepos += reclen;
#endif

      /* Skip deleted files.  */
    }
  while (dp->d_ino == 0);

  if (dp != NULL)
    {
#ifdef GETDENTS_64BIT_ALIGNED
      /* The d_reclen value might include padding which is not part of
	 the DIRENT_TYPE data structure.  */
      reclen = MIN (reclen, sizeof (DIRENT_TYPE));
#endif
      *result = memcpy (entry, dp, reclen);
#ifdef GETDENTS_64BIT_ALIGNED
      entry->d_reclen = reclen;
#endif
    }
  else
    *result = NULL;

  __libc_lock_unlock (dirp->lock);

  return dp != NULL ? 0 : reclen ? errno : 0;
}

#ifdef __READDIR_R_ALIAS
weak_alias (__readdir_r, readdir_r)
#endif