1/* savedir.c -- save the list of files in a directory in a string
2
3   Copyright (C) 1990, 1997, 1998, 1999, 2000, 2001, 2003, 2004, 2005,
4   2006 Free Software Foundation, Inc.
5
6   This program is free software: you can redistribute it and/or modify
7   it under the terms of the GNU General Public License as published by
8   the Free Software Foundation; either version 3 of the License, or
9   (at your option) any later version.
10
11   This program is distributed in the hope that it will be useful,
12   but WITHOUT ANY WARRANTY; without even the implied warranty of
13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14   GNU General Public License for more details.
15
16   You should have received a copy of the GNU General Public License
17   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
18
19/* Written by David MacKenzie <djm@gnu.ai.mit.edu>. */
20
21#include <config.h>
22
23#include "savedir.h"
24
25#include <sys/types.h>
26
27#include <errno.h>
28
29#include <dirent.h>
30#ifndef _D_EXACT_NAMLEN
31# define _D_EXACT_NAMLEN(dp)	strlen ((dp)->d_name)
32#endif
33
34#include <stddef.h>
35#include <stdlib.h>
36#include <string.h>
37
38#include "openat.h"
39#include "xalloc.h"
40
41#ifndef NAME_SIZE_DEFAULT
42# define NAME_SIZE_DEFAULT 512
43#endif
44
45/* The results of opendir() in this file are not used with dirfd and fchdir,
46   therefore save some unnecessary work in fchdir.c.  */
47#undef opendir
48#undef closedir
49
50/* Return a freshly allocated string containing the file names
51   in directory DIRP, separated by '\0' characters;
52   the end is marked by two '\0' characters in a row.
53   Return NULL (setting errno) if DIRP cannot be read or closed.
54   If DIRP is NULL, return NULL without affecting errno.  */
55
56static char *
57savedirstream (DIR *dirp)
58{
59  char *name_space;
60  size_t allocated = NAME_SIZE_DEFAULT;
61  size_t used = 0;
62  int save_errno;
63
64  if (dirp == NULL)
65    return NULL;
66
67  name_space = xmalloc (allocated);
68
69  for (;;)
70    {
71      struct dirent const *dp;
72      char const *entry;
73
74      errno = 0;
75      dp = readdir (dirp);
76      if (! dp)
77	break;
78
79      /* Skip "", ".", and "..".  "" is returned by at least one buggy
80         implementation: Solaris 2.4 readdir on NFS file systems.  */
81      entry = dp->d_name;
82      if (entry[entry[0] != '.' ? 0 : entry[1] != '.' ? 1 : 2] != '\0')
83	{
84	  size_t entry_size = _D_EXACT_NAMLEN (dp) + 1;
85	  if (used + entry_size < used)
86	    xalloc_die ();
87	  if (allocated <= used + entry_size)
88	    {
89	      do
90		{
91		  if (2 * allocated < allocated)
92		    xalloc_die ();
93		  allocated *= 2;
94		}
95	      while (allocated <= used + entry_size);
96
97	      name_space = xrealloc (name_space, allocated);
98	    }
99	  memcpy (name_space + used, entry, entry_size);
100	  used += entry_size;
101	}
102    }
103  name_space[used] = '\0';
104  save_errno = errno;
105  if (closedir (dirp) != 0)
106    save_errno = errno;
107  if (save_errno != 0)
108    {
109      free (name_space);
110      errno = save_errno;
111      return NULL;
112    }
113  return name_space;
114}
115
116/* Return a freshly allocated string containing the file names
117   in directory DIR, separated by '\0' characters;
118   the end is marked by two '\0' characters in a row.
119   Return NULL (setting errno) if DIR cannot be opened, read, or closed.  */
120
121char *
122savedir (char const *dir)
123{
124  return savedirstream (opendir (dir));
125}
126
127/* Return a freshly allocated string containing the file names
128   in directory FD, separated by '\0' characters;
129   the end is marked by two '\0' characters in a row.
130   Return NULL (setting errno) if FD cannot be read or closed.  */
131
132char *
133fdsavedir (int fd)
134{
135  return savedirstream (fdopendir (fd));
136}
137