1 /* savedir.c -- save the list of files in a directory in a string
2
3 Copyright (C) 1990, 1997-2001, 2003-2006, 2009-2017 Free Software
4 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 "xalloc.h"
39
40 typedef struct
41 {
42 char *name;
43 #if D_INO_IN_DIRENT
44 ino_t ino;
45 #endif
46 } direntry_t;
47
48 /* Compare the names of two directory entries */
49
50 static int
direntry_cmp_name(void const * a,void const * b)51 direntry_cmp_name (void const *a, void const *b)
52 {
53 direntry_t const *dea = a;
54 direntry_t const *deb = b;
55
56 return strcmp (dea->name, deb->name);
57 }
58
59 #if D_INO_IN_DIRENT
60 /* Compare the inode numbers of two directory entries */
61
62 static int
direntry_cmp_inode(void const * a,void const * b)63 direntry_cmp_inode (void const *a, void const *b)
64 {
65 direntry_t const *dea = a;
66 direntry_t const *deb = b;
67
68 return dea->ino < deb->ino ? -1 : dea->ino > deb->ino;
69 }
70 #endif
71
72 typedef int (*comparison_function) (void const *, void const *);
73
74 static comparison_function const comparison_function_table[] =
75 {
76 0,
77 direntry_cmp_name
78 #if D_INO_IN_DIRENT
79 , direntry_cmp_inode
80 #endif
81 };
82
83 /* Return a freshly allocated string containing the file names
84 in directory DIRP, separated by '\0' characters;
85 the end is marked by two '\0' characters in a row.
86 Returned values are sorted according to OPTION.
87 Return NULL (setting errno) if DIRP cannot be read.
88 If DIRP is NULL, return NULL without affecting errno. */
89
90 char *
streamsavedir(DIR * dirp,enum savedir_option option)91 streamsavedir (DIR *dirp, enum savedir_option option)
92 {
93 char *name_space = NULL;
94 size_t allocated = 0;
95 direntry_t *entries = NULL;
96 size_t entries_allocated = 0;
97 size_t entries_used = 0;
98 size_t used = 0;
99 int readdir_errno;
100 comparison_function cmp = comparison_function_table[option];
101
102 if (dirp == NULL)
103 return NULL;
104
105 for (;;)
106 {
107 struct dirent const *dp;
108 char const *entry;
109
110 errno = 0;
111 dp = readdir (dirp);
112 if (! dp)
113 break;
114
115 /* Skip "", ".", and "..". "" is returned by at least one buggy
116 implementation: Solaris 2.4 readdir on NFS file systems. */
117 entry = dp->d_name;
118 if (entry[entry[0] != '.' ? 0 : entry[1] != '.' ? 1 : 2] != '\0')
119 {
120 size_t entry_size = _D_EXACT_NAMLEN (dp) + 1;
121 if (cmp)
122 {
123 if (entries_allocated == entries_used)
124 {
125 size_t n = entries_allocated;
126 entries = x2nrealloc (entries, &n, sizeof *entries);
127 entries_allocated = n;
128 }
129 entries[entries_used].name = xstrdup (entry);
130 #if D_INO_IN_DIRENT
131 entries[entries_used].ino = dp->d_ino;
132 #endif
133 entries_used++;
134 }
135 else
136 {
137 if (allocated - used <= entry_size)
138 {
139 size_t n = used + entry_size;
140 if (n < used)
141 xalloc_die ();
142 name_space = x2nrealloc (name_space, &n, 1);
143 allocated = n;
144 }
145 memcpy (name_space + used, entry, entry_size);
146 }
147 used += entry_size;
148 }
149 }
150
151 readdir_errno = errno;
152 if (readdir_errno != 0)
153 {
154 free (entries);
155 free (name_space);
156 errno = readdir_errno;
157 return NULL;
158 }
159
160 if (cmp)
161 {
162 size_t i;
163
164 if (entries_used)
165 qsort (entries, entries_used, sizeof *entries, cmp);
166 name_space = xmalloc (used + 1);
167 used = 0;
168 for (i = 0; i < entries_used; i++)
169 {
170 char *dest = name_space + used;
171 used += stpcpy (dest, entries[i].name) - dest + 1;
172 free (entries[i].name);
173 }
174 free (entries);
175 }
176 else if (used == allocated)
177 name_space = xrealloc (name_space, used + 1);
178
179 name_space[used] = '\0';
180 return name_space;
181 }
182
183 /* Return a freshly allocated string containing the file names
184 in directory DIR, separated by '\0' characters;
185 the end is marked by two '\0' characters in a row.
186 Return NULL (setting errno) if DIR cannot be opened, read, or closed. */
187
188 char *
savedir(char const * dir,enum savedir_option option)189 savedir (char const *dir, enum savedir_option option)
190 {
191 DIR *dirp = opendir (dir);
192 if (! dirp)
193 return NULL;
194 else
195 {
196 char *name_space = streamsavedir (dirp, option);
197 if (closedir (dirp) != 0)
198 {
199 int closedir_errno = errno;
200 free (name_space);
201 errno = closedir_errno;
202 return NULL;
203 }
204 return name_space;
205 }
206 }
207