1 /* -*- buffer-read-only: t -*- vi: set ro: */
2 /* DO NOT EDIT! GENERATED AUTOMATICALLY! */
3 /* backupfile.c -- make Emacs style backup file names
5 Copyright (C) 1990-2006, 2009-2013 Free Software Foundation, Inc.
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 3 of the License, or
10 (at your option) any later version.
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. If not, see <http://www.gnu.org/licenses/>. */
20 /* Written by Paul Eggert and David MacKenzie.
21 Some algorithms adapted from GNU Emacs. */
25 #include "backupfile.h"
41 #ifndef _D_EXACT_NAMLEN
42 # define _D_EXACT_NAMLEN(dp) strlen ((dp)->d_name)
45 # define REAL_DIR_ENTRY(dp) ((dp)->d_ino != 0)
47 # define REAL_DIR_ENTRY(dp) 1
50 #if ! (HAVE_PATHCONF && defined _PC_NAME_MAX)
51 # define pathconf(file, option) (errno = -1)
54 #ifndef _POSIX_NAME_MAX
55 # define _POSIX_NAME_MAX 14
58 # define SIZE_MAX ((size_t) -1)
61 #if defined _XOPEN_NAME_MAX
62 # define NAME_MAX_MINIMUM _XOPEN_NAME_MAX
64 # define NAME_MAX_MINIMUM _POSIX_NAME_MAX
67 #ifndef HAVE_DOS_FILE_NAMES
68 # define HAVE_DOS_FILE_NAMES 0
70 #ifndef HAVE_LONG_FILE_NAMES
71 # define HAVE_LONG_FILE_NAMES 0
74 /* ISDIGIT differs from isdigit, as follows:
75 - Its arg may be any int or unsigned int; it need not be an unsigned char
77 - It's typically faster.
78 POSIX says that only '0' through '9' are digits. Prefer ISDIGIT to
79 ISDIGIT unless it's important to use the locale's definition
80 of "digit" even when the host does not conform to POSIX. */
81 #define ISDIGIT(c) ((unsigned int) (c) - '0' <= 9)
83 /* The extension added to file names to produce a simple (as opposed
84 to numbered) backup file name. */
85 char const *simple_backup_suffix = "~";
88 /* If FILE (which was of length FILELEN before an extension was
89 appended to it) is too long, replace the extension with the single
90 char E. If the result is still too long, remove the char just
94 check_extension (char *file, size_t filelen, char e)
96 char *base = last_component (file);
97 size_t baselen = base_len (base);
98 size_t baselen_max = HAVE_LONG_FILE_NAMES ? 255 : NAME_MAX_MINIMUM;
100 if (HAVE_DOS_FILE_NAMES || NAME_MAX_MINIMUM < baselen)
102 /* The new base name is long enough to require a pathconf check. */
105 /* Temporarily modify the buffer into its parent directory name,
106 invoke pathconf on the directory, and then restore the buffer. */
107 char tmp[sizeof "."];
108 memcpy (tmp, base, sizeof ".");
111 name_max = pathconf (file, _PC_NAME_MAX);
112 if (0 <= name_max || errno == 0)
114 long size = baselen_max = name_max;
115 if (name_max != size)
116 baselen_max = SIZE_MAX;
118 memcpy (base, tmp, sizeof ".");
121 if (HAVE_DOS_FILE_NAMES && baselen_max <= 12)
123 /* Live within DOS's 8.3 limit. */
124 char *dot = strchr (base, '.');
129 char const *second_dot = strchr (dot + 1, '.');
130 baselen_max = (second_dot
132 : dot + 1 - base + 3);
136 if (baselen_max < baselen)
138 baselen = file + filelen - base;
139 if (baselen_max <= baselen)
140 baselen = baselen_max - 1;
142 base[baselen + 1] = '\0';
146 /* Returned values for NUMBERED_BACKUP. */
148 enum numbered_backup_result
150 /* The new backup name is the same length as an existing backup
151 name, so it's valid for that directory. */
152 BACKUP_IS_SAME_LENGTH,
154 /* Some backup names already exist, but the returned name is longer
155 than any of them, and its length should be checked. */
158 /* There are no existing backup names. The new name's length
159 should be checked. */
163 /* *BUFFER contains a file name. Store into *BUFFER the next backup
164 name for the named file, with a version number greater than all the
165 existing numbered backups. Reallocate *BUFFER as necessary; its
166 initial allocated size is BUFFER_SIZE, which must be at least 4
167 bytes longer than the file name to make room for the initially
168 appended ".~1". FILELEN is the length of the original file name.
169 The returned value indicates what kind of backup was found. If an
170 I/O or other read error occurs, use the highest backup number that
173 static enum numbered_backup_result
174 numbered_backup (char **buffer, size_t buffer_size, size_t filelen)
176 enum numbered_backup_result result = BACKUP_IS_NEW;
180 size_t versionlenmax = 1;
181 char *base = last_component (buf);
182 size_t base_offset = base - buf;
183 size_t baselen = base_len (base);
185 /* Temporarily modify the buffer into its parent directory name,
186 open the directory, and then restore the buffer. */
187 char tmp[sizeof "."];
188 memcpy (tmp, base, sizeof ".");
190 dirp = opendir (buf);
191 memcpy (base, tmp, sizeof ".");
192 strcpy (base + baselen, ".~1~");
197 while ((dp = readdir (dirp)) != NULL)
205 if (! REAL_DIR_ENTRY (dp) || _D_EXACT_NAMLEN (dp) < baselen + 4)
208 if (memcmp (buf + base_offset, dp->d_name, baselen + 2) != 0)
211 p = dp->d_name + baselen + 2;
213 /* Check whether this file has a version number and if so,
214 whether it is larger. Use string operations rather than
215 integer arithmetic, to avoid problems with integer overflow. */
217 if (! ('1' <= *p && *p <= '9'))
219 all_9s = (*p == '9');
220 for (versionlen = 1; ISDIGIT (p[versionlen]); versionlen++)
221 all_9s &= (p[versionlen] == '9');
223 if (! (p[versionlen] == '~' && !p[versionlen + 1]
224 && (versionlenmax < versionlen
225 || (versionlenmax == versionlen
226 && memcmp (buf + filelen + 2, p, versionlen) <= 0))))
229 /* This directory has the largest version number seen so far.
230 Append this highest numbered extension to the file name,
231 prepending '0' to the number if it is all 9s. */
233 versionlenmax = all_9s + versionlen;
234 result = (all_9s ? BACKUP_IS_LONGER : BACKUP_IS_SAME_LENGTH);
235 new_buflen = filelen + 2 + versionlenmax + 1;
236 if (buffer_size <= new_buflen)
238 buf = xnrealloc (buf, 2, new_buflen);
239 buffer_size = new_buflen * 2;
246 memcpy (q, p, versionlen + 2);
248 /* Add 1 to the version number. */
261 /* Return the name of the new backup file for the existing file FILE,
262 allocated with malloc. Report an error and fail if out of memory.
263 Do not call this function if backup_type == no_backups. */
266 find_backup_file_name (char const *file, enum backup_type backup_type)
268 size_t filelen = strlen (file);
273 /* Allow room for simple or ".~N~" backups. The guess must be at
274 least sizeof ".~1~", but otherwise will be adjusted as needed. */
275 size_t simple_backup_suffix_size = strlen (simple_backup_suffix) + 1;
276 size_t backup_suffix_size_guess = simple_backup_suffix_size;
277 enum { GUESS = sizeof ".~12345~" };
278 if (backup_suffix_size_guess < GUESS)
279 backup_suffix_size_guess = GUESS;
281 ssize = filelen + backup_suffix_size_guess + 1;
283 memcpy (s, file, filelen + 1);
285 if (backup_type != simple_backups)
286 switch (numbered_backup (&s, ssize, filelen))
288 case BACKUP_IS_SAME_LENGTH:
291 case BACKUP_IS_LONGER:
296 simple = (backup_type == numbered_existing_backups);
301 memcpy (s + filelen, simple_backup_suffix, simple_backup_suffix_size);
302 check_extension (s, filelen, '~');
306 static char const * const backup_args[] =
308 /* In a series of synonyms, present the most meaningful first, so
309 that argmatch_valid be more readable. */
317 static const enum backup_type backup_types[] =
319 no_backups, no_backups,
320 simple_backups, simple_backups,
321 numbered_existing_backups, numbered_existing_backups,
322 numbered_backups, numbered_backups
325 /* Ensure that these two vectors have the same number of elements,
326 not counting the final NULL in the first one. */
327 ARGMATCH_VERIFY (backup_args, backup_types);
329 /* Return the type of backup specified by VERSION.
330 If VERSION is NULL or the empty string, return numbered_existing_backups.
331 If VERSION is invalid or ambiguous, fail with a diagnostic appropriate
332 for the specified CONTEXT. Unambiguous abbreviations are accepted. */
335 get_version (char const *context, char const *version)
337 if (version == 0 || *version == 0)
338 return numbered_existing_backups;
340 return XARGMATCH (context, version, backup_args, backup_types);
344 /* Return the type of backup specified by VERSION.
345 If VERSION is NULL, use the value of the envvar VERSION_CONTROL.
346 If the specified string is invalid or ambiguous, fail with a diagnostic
347 appropriate for the specified CONTEXT.
348 Unambiguous abbreviations are accepted. */
351 xget_version (char const *context, char const *version)
353 if (version && *version)
354 return get_version (context, version);
356 return get_version ("$VERSION_CONTROL", getenv ("VERSION_CONTROL"));