1 /* backupfile.c -- make Emacs style backup file names
2 Copyright (C) 1990 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; if not, write to the Free Software
16 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
18 /* David MacKenzie <djm@gnu.ai.mit.edu>.
19 Some algorithms adapted from GNU Emacs. */
23 #include <sys/types.h>
24 #include "backupfile.h"
25 #if defined(STDC_HEADERS) || defined(HAVE_STRING_H)
31 #define rindex strrchr
37 #if defined(DIRENT) || defined(_POSIX_VERSION)
39 #define NLENGTH(direct) (strlen((direct)->d_name))
40 #else /* not (DIRENT or _POSIX_VERSION) */
42 #define NLENGTH(direct) ((direct)->d_namlen)
52 #endif /* DIRENT or _POSIX_VERSION */
55 /* Fake a return value. */
56 #define CLOSEDIR(d) (closedir (d), 0)
58 #define CLOSEDIR(d) closedir (d)
67 #if !defined (isascii) || defined (STDC_HEADERS)
72 #define ISDIGIT(c) (isascii ((unsigned char ) c) \
73 && isdigit ((unsigned char) (c)))
75 #if defined (HAVE_UNISTD_H)
79 #if defined (_POSIX_VERSION)
80 /* POSIX does not require that the d_ino field be present, and some
81 systems do not provide it. */
82 #define REAL_DIR_ENTRY(dp) 1
84 #define REAL_DIR_ENTRY(dp) ((dp)->d_ino != 0)
87 /* Which type of backup file names are generated. */
88 enum backup_type backup_type = none;
90 /* The extension added to file names to produce a simple (as opposed
91 to numbered) backup file name. */
92 char *simple_backup_suffix = "~";
96 static char *concat ();
97 char *find_backup_file_name ();
98 static char *make_version_name ();
99 static int max_backup_version ();
100 static int version_number ();
102 /* Return the name of the new backup file for file FILE,
103 allocated with malloc. Return 0 if out of memory.
104 FILE must not end with a '/' unless it is the root directory.
105 Do not call this function if backup_type == none. */
108 find_backup_file_name (file)
115 if (backup_type == simple)
116 return concat (file, simple_backup_suffix);
117 base_versions = concat (basename (file), ".~");
118 if (base_versions == 0)
120 dir = dirname (file);
123 free (base_versions);
126 highest_backup = max_backup_version (base_versions, dir);
127 free (base_versions);
129 if (backup_type == numbered_existing && highest_backup == 0)
130 return concat (file, simple_backup_suffix);
131 return make_version_name (file, highest_backup + 1);
134 /* Return the number of the highest-numbered backup file for file
135 FILE in directory DIR. If there are no numbered backups
136 of FILE in DIR, or an error occurs reading DIR, return 0.
137 FILE should already have ".~" appended to it. */
140 max_backup_version (file, dir)
147 int file_name_length;
149 dirp = opendir (dir);
154 file_name_length = strlen (file);
156 while ((dp = readdir (dirp)) != 0)
158 if (!REAL_DIR_ENTRY (dp) || NLENGTH (dp) <= file_name_length)
161 this_version = version_number (file, dp->d_name, file_name_length);
162 if (this_version > highest_version)
163 highest_version = this_version;
167 return highest_version;
170 /* Return a string, allocated with malloc, containing
171 "FILE.~VERSION~". Return 0 if out of memory. */
174 make_version_name (file, version)
180 backup_name = malloc (strlen (file) + 16);
181 if (backup_name == 0)
183 sprintf (backup_name, "%s.~%d~", file, version);
187 /* If BACKUP is a numbered backup of BASE, return its version number;
188 otherwise return 0. BASE_LENGTH is the length of BASE.
189 BASE should already have ".~" appended to it. */
192 version_number (base, backup, base_length)
201 if (!strncmp (base, backup, base_length) && ISDIGIT (backup[base_length]))
203 for (p = &backup[base_length]; ISDIGIT (*p); ++p)
204 version = version * 10 + *p - '0';
205 if (p[0] != '~' || p[1])
211 /* Return the newly-allocated concatenation of STR1 and STR2.
212 If out of memory, return 0. */
219 int str1_length = strlen (str1);
221 newstr = malloc (str1_length + strlen (str2) + 1);
224 strcpy (newstr, str1);
225 strcpy (newstr + str1_length, str2);