1 /* backupfile.c -- make Emacs style backup file names
2 Copyright (C) 1990,1991,1992,1993,1995,1997 Free Software Foundation, Inc.
3
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 2, or (at your option)
7 any later version.
8
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
13
14 You should have received a copy of the GNU General Public License
15 along with this program; see the file COPYING.
16 If not, write to the Free Software Foundation,
17 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
18
19 /* Written by David MacKenzie <djm@gnu.ai.mit.edu>.
20 Some algorithms adapted from GNU Emacs. */
21
22 #if HAVE_CONFIG_H
23 # include <config.h>
24 #endif
25
26 #include <argmatch.h>
27 #include <backupfile.h>
28
29 #include <stdio.h>
30 #include <sys/types.h>
31 #if HAVE_STRING_H
32 # include <string.h>
33 #else
34 # include <strings.h>
35 #endif
36
37 #if HAVE_DIRENT_H
38 # include <dirent.h>
39 # define NLENGTH(direct) strlen ((direct)->d_name)
40 #else
41 # define dirent direct
42 # define NLENGTH(direct) ((size_t) (direct)->d_namlen)
43 # if HAVE_SYS_NDIR_H
44 # include <sys/ndir.h>
45 # endif
46 # if HAVE_SYS_DIR_H
47 # include <sys/dir.h>
48 # endif
49 # if HAVE_NDIR_H
50 # include <ndir.h>
51 # endif
52 #endif
53
54 #if CLOSEDIR_VOID
55 /* Fake a return value. */
56 # define CLOSEDIR(d) (closedir (d), 0)
57 #else
58 # define CLOSEDIR(d) closedir (d)
59 #endif
60
61 #if STDC_HEADERS
62 # include <stdlib.h>
63 #else
64 char *malloc ();
65 #endif
66
67 #if HAVE_DIRENT_H || HAVE_NDIR_H || HAVE_SYS_DIR_H || HAVE_SYS_NDIR_H
68 # define HAVE_DIR 1
69 #else
70 # define HAVE_DIR 0
71 #endif
72
73 #if HAVE_LIMITS_H
74 # include <limits.h>
75 #endif
76 #ifndef CHAR_BIT
77 #define CHAR_BIT 8
78 #endif
79 /* Upper bound on the string length of an integer converted to string.
80 302 / 1000 is ceil (log10 (2.0)). Subtract 1 for the sign bit;
81 add 1 for integer division truncation; add 1 more for a minus sign. */
82 #define INT_STRLEN_BOUND(t) ((sizeof (t) * CHAR_BIT - 1) * 302 / 1000 + 2)
83
84 /* ISDIGIT differs from isdigit, as follows:
85 - Its arg may be any int or unsigned int; it need not be an unsigned char.
86 - It's guaranteed to evaluate its argument exactly once.
87 - It's typically faster.
88 Posix 1003.2-1992 section 2.5.2.1 page 50 lines 1556-1558 says that
89 only '0' through '9' are digits. Prefer ISDIGIT to isdigit unless
90 it's important to use the locale's definition of `digit' even when the
91 host does not conform to Posix. */
92 #define ISDIGIT(c) ((unsigned) (c) - '0' <= 9)
93
94 #if D_INO_IN_DIRENT
95 # define REAL_DIR_ENTRY(dp) ((dp)->d_ino != 0)
96 #else
97 # define REAL_DIR_ENTRY(dp) 1
98 #endif
99
100 /* Which type of backup file names are generated. */
101 enum backup_type backup_type = none;
102
103 /* The extension added to file names to produce a simple (as opposed
104 to numbered) backup file name. */
105 const char *simple_backup_suffix = ".orig";
106
107 static int max_backup_version __BACKUPFILE_P ((const char *, const char *));
108 static int version_number __BACKUPFILE_P ((const char *, const char *, size_t));
109
110 /* Return the name of the new backup file for file FILE,
111 allocated with malloc. Return 0 if out of memory.
112 FILE must not end with a '/' unless it is the root directory.
113 Do not call this function if backup_type == none. */
114
115 char *
find_backup_file_name(file)116 find_backup_file_name (file)
117 const char *file;
118 {
119 size_t backup_suffix_size_max;
120 size_t file_len = strlen (file);
121 size_t numbered_suffix_size_max = INT_STRLEN_BOUND (int) + 4;
122 char *s;
123 const char *suffix = simple_backup_suffix;
124
125 /* Allow room for simple or `.~N~' backups. */
126 backup_suffix_size_max = strlen (simple_backup_suffix) + 1;
127 if (HAVE_DIR && backup_suffix_size_max < numbered_suffix_size_max)
128 backup_suffix_size_max = numbered_suffix_size_max;
129
130 s = malloc (file_len + backup_suffix_size_max + numbered_suffix_size_max);
131 if (s)
132 {
133 strcpy (s, file);
134
135 #if HAVE_DIR
136 if (backup_type != simple)
137 {
138 int highest_backup;
139 size_t dir_len = base_name (s) - s;
140
141 strcpy (s + dir_len, ".");
142 highest_backup = max_backup_version (file + dir_len, s);
143 if (! (backup_type == numbered_existing && highest_backup == 0))
144 {
145 char *numbered_suffix = s + (file_len + backup_suffix_size_max);
146 sprintf (numbered_suffix, ".~%d~", highest_backup + 1);
147 suffix = numbered_suffix;
148 }
149 strcpy (s, file);
150 }
151 #endif /* HAVE_DIR */
152
153 addext (s, suffix, '~');
154 }
155 return s;
156 }
157
158 #if HAVE_DIR
159
160 /* Return the number of the highest-numbered backup file for file
161 FILE in directory DIR. If there are no numbered backups
162 of FILE in DIR, or an error occurs reading DIR, return 0.
163 */
164
165 static int
max_backup_version(file,dir)166 max_backup_version (file, dir)
167 const char *file;
168 const char *dir;
169 {
170 DIR *dirp;
171 struct dirent *dp;
172 int highest_version;
173 int this_version;
174 size_t file_name_length;
175
176 dirp = opendir (dir);
177 if (!dirp)
178 return 0;
179
180 highest_version = 0;
181 file_name_length = strlen (file);
182
183 while ((dp = readdir (dirp)) != 0)
184 {
185 if (!REAL_DIR_ENTRY (dp) || NLENGTH (dp) < file_name_length + 4)
186 continue;
187
188 this_version = version_number (file, dp->d_name, file_name_length);
189 if (this_version > highest_version)
190 highest_version = this_version;
191 }
192 if (CLOSEDIR (dirp))
193 return 0;
194 return highest_version;
195 }
196
197 /* If BACKUP is a numbered backup of BASE, return its version number;
198 otherwise return 0. BASE_LENGTH is the length of BASE.
199 */
200
201 static int
version_number(base,backup,base_length)202 version_number (base, backup, base_length)
203 const char *base;
204 const char *backup;
205 size_t base_length;
206 {
207 int version;
208 const char *p;
209
210 version = 0;
211 if (strncmp (base, backup, base_length) == 0
212 && backup[base_length] == '.'
213 && backup[base_length + 1] == '~')
214 {
215 for (p = &backup[base_length + 2]; ISDIGIT (*p); ++p)
216 version = version * 10 + *p - '0';
217 if (p[0] != '~' || p[1])
218 version = 0;
219 }
220 return version;
221 }
222 #endif /* HAVE_DIR */
223
224 static const char * const backup_args[] =
225 {
226 "never", "simple", "nil", "existing", "t", "numbered", 0
227 };
228
229 static const enum backup_type backup_types[] =
230 {
231 simple, simple, numbered_existing, numbered_existing, numbered, numbered
232 };
233
234 /* Return the type of backup indicated by VERSION.
235 Unique abbreviations are accepted. */
236
237 enum backup_type
get_version(version)238 get_version (version)
239 const char *version;
240 {
241 int i;
242
243 if (version == 0 || *version == 0)
244 return numbered_existing;
245 i = argmatch (version, backup_args);
246 if (i < 0)
247 {
248 invalid_arg ("version control type", version, i);
249 exit (2);
250 }
251 return backup_types[i];
252 }
253