1 /* backupfile.c -- make Emacs style backup file names
3 Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
4 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006 Free Software
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program; see the file COPYING.
19 If not, write to the Free Software Foundation,
20 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
22 /* Written by Paul Eggert and David MacKenzie.
23 Some algorithms adapted from GNU Emacs. */
29 #include "backupfile.h"
46 # define NLENGTH(direct) strlen ((direct)->d_name)
48 # define dirent direct
49 # define NLENGTH(direct) ((size_t) (direct)->d_namlen)
51 # include <sys/ndir.h>
61 #if HAVE_DIRENT_H || HAVE_NDIR_H || HAVE_SYS_DIR_H || HAVE_SYS_NDIR_H
68 # define REAL_DIR_ENTRY(dp) ((dp)->d_ino != 0)
70 # define REAL_DIR_ENTRY(dp) 1
73 #if ! (HAVE_PATHCONF && defined _PC_NAME_MAX)
74 # define pathconf(file, option) (errno = -1)
77 #ifndef _POSIX_NAME_MAX
78 # define _POSIX_NAME_MAX 14
81 # define SIZE_MAX ((size_t) -1)
84 #if defined _XOPEN_NAME_MAX
85 # define NAME_MAX_MINIMUM _XOPEN_NAME_MAX
87 # define NAME_MAX_MINIMUM _POSIX_NAME_MAX
90 #ifndef HAVE_DOS_FILE_NAMES
91 # define HAVE_DOS_FILE_NAMES 0
93 #ifndef HAVE_LONG_FILE_NAMES
94 # define HAVE_LONG_FILE_NAMES 0
97 /* ISDIGIT differs from isdigit, as follows:
98 - Its arg may be any int or unsigned int; it need not be an unsigned char
100 - It's typically faster.
101 POSIX says that only '0' through '9' are digits. Prefer ISDIGIT to
102 ISDIGIT unless it's important to use the locale's definition
103 of `digit' even when the host does not conform to POSIX. */
104 #define ISDIGIT(c) ((unsigned int) (c) - '0' <= 9)
106 /* The extension added to file names to produce a simple (as opposed
107 to numbered) backup file name. */
108 char const *simple_backup_suffix = "~";
111 /* If FILE (which was of length FILELEN before an extension was
112 appended to it) is too long, replace the extension with the single
113 char E. If the result is still too long, remove the char just
117 check_extension (char *file, size_t filelen, char e)
119 char *base = last_component (file);
120 size_t baselen = base_len (base);
121 size_t baselen_max = HAVE_LONG_FILE_NAMES ? 255 : NAME_MAX_MINIMUM;
123 if (HAVE_DOS_FILE_NAMES || NAME_MAX_MINIMUM < baselen)
125 /* The new base name is long enough to require a pathconf check. */
128 /* Temporarily modify the buffer into its parent directory name,
129 invoke pathconf on the directory, and then restore the buffer. */
130 char tmp[sizeof "."];
131 memcpy (tmp, base, sizeof ".");
134 name_max = pathconf (file, _PC_NAME_MAX);
135 if (0 <= name_max || errno == 0)
137 long size = baselen_max = name_max;
138 if (name_max != size)
139 baselen_max = SIZE_MAX;
141 memcpy (base, tmp, sizeof ".");
144 if (HAVE_DOS_FILE_NAMES && baselen_max <= 12)
146 /* Live within DOS's 8.3 limit. */
147 char *dot = strchr (base, '.');
152 char const *second_dot = strchr (dot + 1, '.');
153 baselen_max = (second_dot
155 : dot + 1 - base + 3);
159 if (baselen_max < baselen)
161 baselen = file + filelen - base;
162 if (baselen_max <= baselen)
163 baselen = baselen_max - 1;
165 base[baselen + 1] = '\0';
171 /* Returned values for NUMBERED_BACKUP. */
173 enum numbered_backup_result
175 /* The new backup name is the same length as an existing backup
176 name, so it's valid for that directory. */
177 BACKUP_IS_SAME_LENGTH,
179 /* Some backup names already exist, but the returned name is longer
180 than any of them, and its length should be checked. */
183 /* There are no existing backup names. The new name's length
184 should be checked. */
188 /* *BUFFER contains a file name. Store into *BUFFER the next backup
189 name for the named file, with a version number greater than all the
190 existing numbered backups. Reallocate *BUFFER as necessary; its
191 initial allocated size is BUFFER_SIZE, which must be at least 4
192 bytes longer than the file name to make room for the initially
193 appended ".~1". FILELEN is the length of the original file name.
194 The returned value indicates what kind of backup was found. If an
195 I/O or other read error occurs, use the highest backup number that
198 static enum numbered_backup_result
199 numbered_backup (char **buffer, size_t buffer_size, size_t filelen)
201 enum numbered_backup_result result = BACKUP_IS_NEW;
205 size_t versionlenmax = 1;
206 char *base = last_component (buf);
207 size_t base_offset = base - buf;
208 size_t baselen = base_len (base);
210 /* Temporarily modify the buffer into its parent directory name,
211 open the directory, and then restore the buffer. */
212 char tmp[sizeof "."];
213 memcpy (tmp, base, sizeof ".");
215 dirp = opendir (buf);
216 memcpy (base, tmp, sizeof ".");
217 strcpy (base + baselen, ".~1~");
222 while ((dp = readdir (dirp)) != NULL)
230 if (! REAL_DIR_ENTRY (dp) || NLENGTH (dp) < baselen + 4)
233 if (memcmp (buf + base_offset, dp->d_name, baselen + 2) != 0)
236 p = dp->d_name + baselen + 2;
238 /* Check whether this file has a version number and if so,
239 whether it is larger. Use string operations rather than
240 integer arithmetic, to avoid problems with integer overflow. */
242 if (! ('1' <= *p && *p <= '9'))
244 all_9s = (*p == '9');
245 for (versionlen = 1; ISDIGIT (p[versionlen]); versionlen++)
246 all_9s &= (p[versionlen] == '9');
248 if (! (p[versionlen] == '~' && !p[versionlen + 1]
249 && (versionlenmax < versionlen
250 || (versionlenmax == versionlen
251 && memcmp (buf + filelen + 2, p, versionlen) <= 0))))
254 /* This directory has the largest version number seen so far.
255 Append this highest numbered extension to the file name,
256 prepending '0' to the number if it is all 9s. */
258 versionlenmax = all_9s + versionlen;
259 result = (all_9s ? BACKUP_IS_LONGER : BACKUP_IS_SAME_LENGTH);
260 new_buflen = filelen + 2 + versionlenmax + 1;
261 if (buffer_size <= new_buflen)
263 buf = xnrealloc (buf, 2, new_buflen);
264 buffer_size = new_buflen * 2;
271 memcpy (q, p, versionlen + 2);
273 /* Add 1 to the version number. */
285 #endif /* HAVE_DIR */
287 /* Return the name of the new backup file for the existing file FILE,
288 allocated with malloc. Report an error and fail if out of memory.
289 Do not call this function if backup_type == no_backups. */
292 find_backup_file_name (char const *file, enum backup_type backup_type)
294 size_t filelen = strlen (file);
299 /* Allow room for simple or ".~N~" backups. The guess must be at
300 least sizeof ".~1~", but otherwise will be adjusted as needed. */
301 size_t simple_backup_suffix_size = strlen (simple_backup_suffix) + 1;
302 size_t backup_suffix_size_guess = simple_backup_suffix_size;
303 enum { GUESS = sizeof ".~12345~" };
304 if (HAVE_DIR && backup_suffix_size_guess < GUESS)
305 backup_suffix_size_guess = GUESS;
307 ssize = filelen + backup_suffix_size_guess + 1;
309 memcpy (s, file, filelen + 1);
312 if (backup_type != simple_backups)
313 switch (numbered_backup (&s, ssize, filelen))
315 case BACKUP_IS_SAME_LENGTH:
318 case BACKUP_IS_LONGER:
323 simple = (backup_type == numbered_existing_backups);
329 memcpy (s + filelen, simple_backup_suffix, simple_backup_suffix_size);
330 check_extension (s, filelen, '~');
334 static char const * const backup_args[] =
336 /* In a series of synonyms, present the most meaningful first, so
337 that argmatch_valid be more readable. */
345 static const enum backup_type backup_types[] =
347 no_backups, no_backups,
348 simple_backups, simple_backups,
349 numbered_existing_backups, numbered_existing_backups,
350 numbered_backups, numbered_backups
353 /* Ensure that these two vectors have the same number of elements,
354 not counting the final NULL in the first one. */
355 ARGMATCH_VERIFY (backup_args, backup_types);
357 /* Return the type of backup specified by VERSION.
358 If VERSION is NULL or the empty string, return numbered_existing_backups.
359 If VERSION is invalid or ambiguous, fail with a diagnostic appropriate
360 for the specified CONTEXT. Unambiguous abbreviations are accepted. */
363 get_version (char const *context, char const *version)
365 if (version == 0 || *version == 0)
366 return numbered_existing_backups;
368 return XARGMATCH (context, version, backup_args, backup_types);
372 /* Return the type of backup specified by VERSION.
373 If VERSION is NULL, use the value of the envvar VERSION_CONTROL.
374 If the specified string is invalid or ambiguous, fail with a diagnostic
375 appropriate for the specified CONTEXT.
376 Unambiguous abbreviations are accepted. */
379 xget_version (char const *context, char const *version)
381 if (version && *version)
382 return get_version (context, version);
384 return get_version ("$VERSION_CONTROL", getenv ("VERSION_CONTROL"));