1 /* savedir.c -- save the list of files in a directory in a string
2
3 Copyright (C) 1990, 1997-2001, 2003-2006, 2009-2023 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 <https://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
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
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 _GL_CMP (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 *
91 streamsavedir (DIR *dirp, enum savedir_option option)
92 {
93 char *name_space = NULL;
94 idx_t allocated = 0;
95 direntry_t *entries = NULL;
96 idx_t entries_allocated = 0;
97 idx_t entries_used = 0;
98 idx_t used = 0;
99 comparison_function cmp = comparison_function_table[option];
100
101 if (dirp == NULL)
102 return NULL;
103
104 for (;;)
105 {
106 struct dirent const *dp;
107 char const *entry;
108
109 errno = 0;
110 dp = readdir (dirp);
111 if (! dp)
112 break;
113
114 /* Skip "", ".", and "..". "" is returned by at least one buggy
115 implementation: Solaris 2.4 readdir on NFS file systems. */
116 entry = dp->d_name;
117 if (entry[entry[0] != '.' ? 0 : entry[1] != '.' ? 1 : 2] != '\0')
118 {
119 idx_t entry_size = _D_EXACT_NAMLEN (dp) + 1;
120 if (cmp)
121 {
122 if (entries_allocated == entries_used)
123 entries = xpalloc (entries, &entries_allocated, 1, -1,
124 sizeof *entries);
125 entries[entries_used].name = xstrdup (entry);
126 #if D_INO_IN_DIRENT
127 entries[entries_used].ino = dp->d_ino;
128 #endif
129 entries_used++;
130 }
131 else
132 {
133 if (allocated - used <= entry_size)
134 name_space = xpalloc (name_space, &allocated,
135 entry_size - (allocated - used),
136 IDX_MAX - 1, sizeof *name_space);
137 memcpy (name_space + used, entry, entry_size);
138 }
139 used += entry_size;
140 }
141 }
142
143 if (errno != 0)
144 {
145 free (entries);
146 free (name_space);
147 return NULL;
148 }
149
150 if (cmp)
151 {
152 if (entries_used)
153 qsort (entries, entries_used, sizeof *entries, cmp);
154 name_space = ximalloc (used + 1);
155 used = 0;
156 for (idx_t i = 0; i < entries_used; i++)
157 {
158 char *dest = name_space + used;
159 used += stpcpy (dest, entries[i].name) - dest + 1;
160 free (entries[i].name);
161 }
162 free (entries);
163 }
164 else if (used == allocated)
165 name_space = xirealloc (name_space, used + 1);
166
167 name_space[used] = '\0';
168 return name_space;
169 }
170
171 /* Return a freshly allocated string containing the file names
172 in directory DIR, separated by '\0' characters;
173 the end is marked by two '\0' characters in a row.
174 Return NULL (setting errno) if DIR cannot be opened, read, or closed. */
175
176 char *
177 savedir (char const *dir, enum savedir_option option)
178 {
179 DIR *dirp = opendir (dir);
180 if (! dirp)
181 return NULL;
182 else
183 {
184 char *name_space = streamsavedir (dirp, option);
185 if (closedir (dirp) != 0)
186 {
187 free (name_space);
188 return NULL;
189 }
190 return name_space;
191 }
192 }