1 /* backupfile.c -- make Emacs style backup file names
2 Copyright (C) 1990-1997, 1998, 1999, 2000 Free Software Foundation, Inc.
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)
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.
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. */
19 /* Written by David MacKenzie <djm@gnu.ai.mit.edu>.
20 Some algorithms adapted from GNU Emacs. */
27 #include <backupfile.h>
30 #include <sys/types.h>
39 # define NLENGTH(direct) strlen ((direct)->d_name)
41 # define dirent direct
42 # define NLENGTH(direct) ((size_t) (direct)->d_namlen)
44 # include <sys/ndir.h>
55 /* Fake a return value. */
56 # define CLOSEDIR(d) (closedir (d), 0)
58 # define CLOSEDIR(d) closedir (d)
65 #ifndef HAVE_DECL_GETENV
66 "this configure-time declaration test was not run"
72 #ifndef HAVE_DECL_MALLOC
73 "this configure-time declaration test was not run"
79 char *base_name PARAMS ((char const *));
81 #if HAVE_DIRENT_H || HAVE_NDIR_H || HAVE_SYS_DIR_H || HAVE_SYS_NDIR_H
93 /* Upper bound on the string length of an integer converted to string.
94 302 / 1000 is ceil (log10 (2.0)). Subtract 1 for the sign bit;
95 add 1 for integer division truncation; add 1 more for a minus sign. */
96 #define INT_STRLEN_BOUND(t) ((sizeof (t) * CHAR_BIT - 1) * 302 / 1000 + 2)
98 /* ISDIGIT differs from isdigit, as follows:
99 - Its arg may be any int or unsigned int; it need not be an unsigned char.
100 - It's guaranteed to evaluate its argument exactly once.
101 - It's typically faster.
102 Posix 1003.2-1992 section 2.5.2.1 page 50 lines 1556-1558 says that
103 only '0' through '9' are digits. Prefer ISDIGIT to isdigit unless
104 it's important to use the locale's definition of `digit' even when the
105 host does not conform to Posix. */
106 #define ISDIGIT(c) ((unsigned) (c) - '0' <= 9)
109 # define REAL_DIR_ENTRY(dp) ((dp)->d_ino != 0)
111 # define REAL_DIR_ENTRY(dp) 1
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 + backup_suffix_size_max + numbered_suffix_size_max);
146 if (backup_type != simple)
149 size_t dir_len = base_name (s) - s;
151 strcpy (s + dir_len, ".");
152 highest_backup = max_backup_version (file + dir_len, s);
153 if (! (backup_type == numbered_existing && highest_backup == 0))
155 char *numbered_suffix = s + (file_len + backup_suffix_size_max);
156 sprintf (numbered_suffix, ".~%d~", highest_backup + 1);
157 suffix = numbered_suffix;
161 #endif /* HAVE_DIR */
163 addext (s, suffix, '~');
170 /* Return the number of the highest-numbered backup file for file
171 FILE in directory DIR. If there are no numbered backups
172 of FILE in DIR, or an error occurs reading DIR, return 0.
176 max_backup_version (const char *file, const char *dir)
182 size_t file_name_length;
184 dirp = opendir (dir);
189 file_name_length = strlen (file);
191 while ((dp = readdir (dirp)) != 0)
193 if (!REAL_DIR_ENTRY (dp) || NLENGTH (dp) < file_name_length + 4)
196 this_version = version_number (file, dp->d_name, file_name_length);
197 if (this_version > highest_version)
198 highest_version = this_version;
202 return highest_version;
205 /* If BACKUP is a numbered backup of BASE, return its version number;
206 otherwise return 0. BASE_LENGTH is the length of BASE.
210 version_number (const char *base, const char *backup, size_t base_length)
216 if (strncmp (base, backup, base_length) == 0
217 && backup[base_length] == '.'
218 && backup[base_length + 1] == '~')
220 for (p = &backup[base_length + 2]; ISDIGIT (*p); ++p)
221 version = version * 10 + *p - '0';
222 if (p[0] != '~' || p[1])
227 #endif /* HAVE_DIR */
229 static const char * const backup_args[] =
231 /* In a series of synonyms, present the most meaning full first, so
232 that argmatch_valid be more readable. */
240 static const enum backup_type backup_types[] =
244 numbered_existing, numbered_existing,
248 /* Return the type of backup specified by VERSION.
249 If VERSION is NULL or the empty string, return numbered_existing.
250 If VERSION is invalid or ambiguous, fail with a diagnostic appropriate
251 for the specified CONTEXT. Unambiguous abbreviations are accepted. */
254 get_version (const char *context, const char *version)
256 if (version == 0 || *version == 0)
257 return numbered_existing;
259 return XARGMATCH (context, version, backup_args, backup_types);
263 /* Return the type of backup specified by VERSION.
264 If VERSION is NULL, use the value of the envvar VERSION_CONTROL.
265 If the specified string is invalid or ambiguous, fail with a diagnostic
266 appropriate for the specified CONTEXT.
267 Unambiguous abbreviations are accepted. */
270 xget_version (const char *context, const char *version)
272 if (version && *version)
273 return get_version (context, version);
275 return get_version ("$VERSION_CONTROL", getenv ("VERSION_CONTROL"));