1 /* backupfile.c -- make Emacs style backup file names
2 Copyright 1990,91,92,93,94,95,96,97,98,99,2000, 2001 Free Software
5 This program is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 2, or (at your option)
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with this program; see the file COPYING.
17 If not, write to the Free Software Foundation,
18 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
20 /* Written by David MacKenzie <djm@gnu.ai.mit.edu>.
21 Some algorithms adapted from GNU Emacs. */
28 #include <sys/types.h>
37 # define NLENGTH(direct) strlen ((direct)->d_name)
39 # define dirent direct
40 # define NLENGTH(direct) ((size_t) (direct)->d_namlen)
42 # include <sys/ndir.h>
53 /* Fake a return value. */
54 # define CLOSEDIR(d) (closedir (d), 0)
56 # define CLOSEDIR(d) closedir (d)
63 #ifndef HAVE_DECL_GETENV
64 "this configure-time declaration test was not run"
70 #ifndef HAVE_DECL_MALLOC
71 "this configure-time declaration test was not run"
77 #if HAVE_DIRENT_H || HAVE_NDIR_H || HAVE_SYS_DIR_H || HAVE_SYS_NDIR_H
89 /* Upper bound on the string length of an integer converted to string.
90 302 / 1000 is ceil (log10 (2.0)). Subtract 1 for the sign bit;
91 add 1 for integer division truncation; add 1 more for a minus sign. */
92 #define INT_STRLEN_BOUND(t) ((sizeof (t) * CHAR_BIT - 1) * 302 / 1000 + 2)
94 /* ISDIGIT differs from isdigit, as follows:
95 - Its arg may be any int or unsigned int; it need not be an unsigned char.
96 - It's guaranteed to evaluate its argument exactly once.
97 - It's typically faster.
98 Posix 1003.2-1992 section 2.5.2.1 page 50 lines 1556-1558 says that
99 only '0' through '9' are digits. Prefer ISDIGIT to isdigit unless
100 it's important to use the locale's definition of `digit' even when the
101 host does not conform to Posix. */
102 #define ISDIGIT(c) ((unsigned) (c) - '0' <= 9)
105 # define REAL_DIR_ENTRY(dp) ((dp)->d_ino != 0)
107 # define REAL_DIR_ENTRY(dp) 1
110 #include "argmatch.h"
111 #include "backupfile.h"
114 /* The extension added to file names to produce a simple (as opposed
115 to numbered) backup file name. */
116 const char *simple_backup_suffix = "~";
118 static int max_backup_version PARAMS ((const char *, const char *));
119 static int version_number PARAMS ((const char *, const char *, size_t));
121 /* Return the name of the new backup file for file FILE,
122 allocated with malloc. Return 0 if out of memory.
123 FILE must not end with a '/' unless it is the root directory.
124 Do not call this function if backup_type == none. */
127 find_backup_file_name (const char *file, enum backup_type backup_type)
129 size_t backup_suffix_size_max;
130 size_t file_len = strlen (file);
131 size_t numbered_suffix_size_max = INT_STRLEN_BOUND (int) + 4;
133 const char *suffix = simple_backup_suffix;
135 /* Allow room for simple or `.~N~' backups. */
136 backup_suffix_size_max = strlen (simple_backup_suffix) + 1;
137 if (HAVE_DIR && backup_suffix_size_max < numbered_suffix_size_max)
138 backup_suffix_size_max = numbered_suffix_size_max;
140 s = malloc (file_len + 1
141 + backup_suffix_size_max + numbered_suffix_size_max);
145 if (backup_type != simple)
148 size_t dirlen = dir_len (file);
150 memcpy (s, file, dirlen);
151 if (dirlen == FILESYSTEM_PREFIX_LEN (file))
154 highest_backup = max_backup_version (base_name (file), s);
155 if (! (backup_type == numbered_existing && highest_backup == 0))
157 char *numbered_suffix = s + (file_len + backup_suffix_size_max);
158 sprintf (numbered_suffix, ".~%d~", highest_backup + 1);
159 suffix = numbered_suffix;
162 #endif /* HAVE_DIR */
165 addext (s, suffix, '~');
172 /* Return the number of the highest-numbered backup file for file
173 FILE in directory DIR. If there are no numbered backups
174 of FILE in DIR, or an error occurs reading DIR, return 0.
178 max_backup_version (const char *file, const char *dir)
184 size_t file_name_length;
186 dirp = opendir (dir);
191 file_name_length = base_len (file);
193 while ((dp = readdir (dirp)) != 0)
195 if (!REAL_DIR_ENTRY (dp) || NLENGTH (dp) < file_name_length + 4)
198 this_version = version_number (file, dp->d_name, file_name_length);
199 if (this_version > highest_version)
200 highest_version = this_version;
204 return highest_version;
207 /* If BACKUP is a numbered backup of BASE, return its version number;
208 otherwise return 0. BASE_LENGTH is the length of BASE.
212 version_number (const char *base, const char *backup, size_t base_length)
218 if (strncmp (base, backup, base_length) == 0
219 && backup[base_length] == '.'
220 && backup[base_length + 1] == '~')
222 for (p = &backup[base_length + 2]; ISDIGIT (*p); ++p)
223 version = version * 10 + *p - '0';
224 if (p[0] != '~' || p[1])
229 #endif /* HAVE_DIR */
231 static const char * const backup_args[] =
233 /* In a series of synonyms, present the most meaning full first, so
234 that argmatch_valid be more readable. */
242 static const enum backup_type backup_types[] =
246 numbered_existing, numbered_existing,
250 /* Return the type of backup specified by VERSION.
251 If VERSION is NULL or the empty string, return numbered_existing.
252 If VERSION is invalid or ambiguous, fail with a diagnostic appropriate
253 for the specified CONTEXT. Unambiguous abbreviations are accepted. */
256 get_version (const char *context, const char *version)
258 if (version == 0 || *version == 0)
259 return numbered_existing;
261 return XARGMATCH (context, version, backup_args, backup_types);
265 /* Return the type of backup specified by VERSION.
266 If VERSION is NULL, use the value of the envvar VERSION_CONTROL.
267 If the specified string is invalid or ambiguous, fail with a diagnostic
268 appropriate for the specified CONTEXT.
269 Unambiguous abbreviations are accepted. */
272 xget_version (const char *context, const char *version)
274 if (version && *version)
275 return get_version (context, version);
277 return get_version ("$VERSION_CONTROL", getenv ("VERSION_CONTROL"));