about summary refs log tree commit diff
path: root/sysdeps/posix/opendir.c
blob: 0875385f65206831a824f01234cd6de5c1527780 (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
/* Copyright (C) 1991-2018 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, see
   <http://www.gnu.org/licenses/>.  */

#include <dirent.h>
#include <fcntl.h>
#include <errno.h>
#include <stdio.h>	/* For BUFSIZ.  */
#include <sys/param.h>	/* For MIN and MAX.  */

#include <not-cancel.h>

/* The st_blksize value of the directory is used as a hint for the
   size of the buffer which receives struct dirent values from the
   kernel.  st_blksize is limited to MAX_DIR_BUFFER_SIZE, in case the
   file system provides a bogus value.  */
#define MAX_DIR_BUFFER_SIZE 1048576U

enum {
  opendir_oflags = O_RDONLY|O_NDELAY|O_DIRECTORY|O_LARGEFILE|O_CLOEXEC
};

static bool
invalid_name (const char *name)
{
  if (__glibc_unlikely (name[0] == '\0'))
    {
      /* POSIX.1-1990 says an empty name gets ENOENT;
	 but `open' might like it fine.  */
      __set_errno (ENOENT);
      return true;
    }
  return false;
}

static DIR *
opendir_tail (int fd)
{
  if (__glibc_unlikely (fd < 0))
    return NULL;

  /* Now make sure this really is a directory and nothing changed since the
     `stat' call.  The S_ISDIR check is superfluous if O_DIRECTORY works,
     but it's cheap and we need the stat call for st_blksize anyway.  */
  struct stat64 statbuf;
  if (__glibc_unlikely (__fxstat64 (_STAT_VER, fd, &statbuf) < 0))
    goto lose;
  if (__glibc_unlikely (! S_ISDIR (statbuf.st_mode)))
    {
      __set_errno (ENOTDIR);
    lose:
      __close_nocancel_nostatus (fd);
      return NULL;
    }

  return __alloc_dir (fd, true, 0, &statbuf);
}


#if IS_IN (libc)
DIR *
__opendirat (int dfd, const char *name)
{
  if (__glibc_unlikely (invalid_name (name)))
    return NULL;

  return opendir_tail (__openat_nocancel (dfd, name, opendir_oflags));
}
#endif


/* Open a directory stream on NAME.  */
DIR *
__opendir (const char *name)
{
  if (__glibc_unlikely (invalid_name (name)))
    return NULL;

  return opendir_tail (__open_nocancel (name, opendir_oflags));
}
weak_alias (__opendir, opendir)

DIR *
__alloc_dir (int fd, bool close_fd, int flags, const struct stat64 *statp)
{
  /* We have to set the close-on-exit flag if the user provided the
     file descriptor.  */
  if (!close_fd
      && __glibc_unlikely (__fcntl_nocancel (fd, F_SETFD, FD_CLOEXEC) < 0))
	goto lose;

  const size_t default_allocation = (4 * BUFSIZ < sizeof (struct dirent64)
				     ? sizeof (struct dirent64) : 4 * BUFSIZ);
  const size_t small_allocation = (BUFSIZ < sizeof (struct dirent64)
				   ? sizeof (struct dirent64) : BUFSIZ);
  size_t allocation = default_allocation;
#ifdef _STATBUF_ST_BLKSIZE
  /* Increase allocation if requested, but not if the value appears to
     be bogus.  */
  if (statp != NULL)
    allocation = MIN (MAX ((size_t) statp->st_blksize, default_allocation),
		      MAX_DIR_BUFFER_SIZE);
#endif

  DIR *dirp = (DIR *) malloc (sizeof (DIR) + allocation);
  if (dirp == NULL)
    {
      allocation = small_allocation;
      dirp = (DIR *) malloc (sizeof (DIR) + allocation);

      if (dirp == NULL)
      lose:
	{
	  if (close_fd)
	    {
	      int save_errno = errno;
	      __close_nocancel_nostatus (fd);
	      __set_errno (save_errno);
	    }
	  return NULL;
	}
    }

  dirp->fd = fd;
#if IS_IN (libc)
  __libc_lock_init (dirp->lock);
#endif
  dirp->allocation = allocation;
  dirp->size = 0;
  dirp->offset = 0;
  dirp->filepos = 0;
  dirp->errcode = 0;

  return dirp;
}