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 Free Software Foundation, Inc.
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 2, or (at your option)
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.
16 You should have received a copy of the GNU General Public License
17 along with this program; see the file COPYING.
18 If not, write to the Free Software Foundation,
19 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
21 /* Written by David MacKenzie <djm@gnu.ai.mit.edu>.
22 Some algorithms adapted from GNU Emacs. */
29 #include <sys/types.h>
38 # define NLENGTH(direct) strlen ((direct)->d_name)
40 # define dirent direct
41 # define NLENGTH(direct) ((size_t) (direct)->d_namlen)
43 # include <sys/ndir.h>
54 /* Fake a return value. */
55 # define CLOSEDIR(d) (closedir (d), 0)
57 # define CLOSEDIR(d) closedir (d)
64 #ifndef HAVE_DECL_GETENV
65 "this configure-time declaration test was not run"
71 #ifndef HAVE_DECL_MALLOC
72 "this configure-time declaration test was not run"
78 #if HAVE_DIRENT_H || HAVE_NDIR_H || HAVE_SYS_DIR_H || HAVE_SYS_NDIR_H
86 /* Upper bound on the string length of an integer converted to string.
87 302 / 1000 is ceil (log10 (2.0)). Subtract 1 for the sign bit;
88 add 1 for integer division truncation; add 1 more for a minus sign. */
89 #define INT_STRLEN_BOUND(t) ((sizeof (t) * CHAR_BIT - 1) * 302 / 1000 + 2)
91 /* ISDIGIT differs from isdigit, as follows:
92 - Its arg may be any int or unsigned int; it need not be an unsigned char.
93 - It's guaranteed to evaluate its argument exactly once.
94 - It's typically faster.
95 POSIX says that only '0' through '9' are digits. Prefer ISDIGIT to
96 ISDIGIT_LOCALE unless it's important to use the locale's definition
97 of `digit' even when the host does not conform to POSIX. */
98 #define ISDIGIT(c) ((unsigned) (c) - '0' <= 9)
101 # define REAL_DIR_ENTRY(dp) ((dp)->d_ino != 0)
103 # define REAL_DIR_ENTRY(dp) 1
106 #include "argmatch.h"
107 #include "backupfile.h"
110 /* The extension added to file names to produce a simple (as opposed
111 to numbered) backup file name. */
112 const char *simple_backup_suffix = "~";
114 static int max_backup_version PARAMS ((const char *, const char *));
115 static int version_number PARAMS ((const char *, const char *, size_t));
117 /* Return the name of the new backup file for file FILE,
118 allocated with malloc. Return 0 if out of memory.
119 FILE must not end with a '/' unless it is the root directory.
120 Do not call this function if backup_type == none. */
123 find_backup_file_name (const char *file, enum backup_type backup_type)
125 size_t backup_suffix_size_max;
126 size_t file_len = strlen (file);
127 size_t numbered_suffix_size_max = INT_STRLEN_BOUND (int) + 4;
129 const char *suffix = simple_backup_suffix;
131 /* Allow room for simple or `.~N~' backups. */
132 backup_suffix_size_max = strlen (simple_backup_suffix) + 1;
133 if (HAVE_DIR && backup_suffix_size_max < numbered_suffix_size_max)
134 backup_suffix_size_max = numbered_suffix_size_max;
136 s = malloc (file_len + 1
137 + backup_suffix_size_max + numbered_suffix_size_max);
141 if (backup_type != simple)
144 size_t dirlen = dir_len (file);
146 memcpy (s, file, dirlen);
147 if (dirlen == FILESYSTEM_PREFIX_LEN (file))
150 highest_backup = max_backup_version (base_name (file), s);
151 if (! (backup_type == numbered_existing && highest_backup == 0))
153 char *numbered_suffix = s + (file_len + backup_suffix_size_max);
154 sprintf (numbered_suffix, ".~%d~", highest_backup + 1);
155 suffix = numbered_suffix;
158 #endif /* HAVE_DIR */
161 addext (s, suffix, '~');
168 /* Return the number of the highest-numbered backup file for file
169 FILE in directory DIR. If there are no numbered backups
170 of FILE in DIR, or an error occurs reading DIR, return 0.
174 max_backup_version (const char *file, const char *dir)
180 size_t file_name_length;
182 dirp = opendir (dir);
187 file_name_length = base_len (file);
189 while ((dp = readdir (dirp)) != 0)
191 if (!REAL_DIR_ENTRY (dp) || NLENGTH (dp) < file_name_length + 4)
194 this_version = version_number (file, dp->d_name, file_name_length);
195 if (this_version > highest_version)
196 highest_version = this_version;
200 return highest_version;
203 /* If BACKUP is a numbered backup of BASE, return its version number;
204 otherwise return 0. BASE_LENGTH is the length of BASE.
208 version_number (const char *base, const char *backup, size_t base_length)
214 if (strncmp (base, backup, base_length) == 0
215 && backup[base_length] == '.'
216 && backup[base_length + 1] == '~')
218 for (p = &backup[base_length + 2]; ISDIGIT (*p); ++p)
219 version = version * 10 + *p - '0';
220 if (p[0] != '~' || p[1])
225 #endif /* HAVE_DIR */
227 static const char * const backup_args[] =
229 /* In a series of synonyms, present the most meaning full first, so
230 that argmatch_valid be more readable. */
238 static const enum backup_type backup_types[] =
242 numbered_existing, numbered_existing,
246 /* Return the type of backup specified by VERSION.
247 If VERSION is NULL or the empty string, return numbered_existing.
248 If VERSION is invalid or ambiguous, fail with a diagnostic appropriate
249 for the specified CONTEXT. Unambiguous abbreviations are accepted. */
252 get_version (const char *context, const char *version)
254 if (version == 0 || *version == 0)
255 return numbered_existing;
257 return XARGMATCH (context, version, backup_args, backup_types);
261 /* Return the type of backup specified by VERSION.
262 If VERSION is NULL, use the value of the envvar VERSION_CONTROL.
263 If the specified string is invalid or ambiguous, fail with a diagnostic
264 appropriate for the specified CONTEXT.
265 Unambiguous abbreviations are accepted. */
268 xget_version (const char *context, const char *version)
270 if (version && *version)
271 return get_version (context, version);
273 return get_version ("$VERSION_CONTROL", getenv ("VERSION_CONTROL"));