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@ai.mit.edu>.
19 Some algorithms adapted from GNU Emacs. */
23 #include <sys/types.h>
24 #include "backupfile.h"
25 #if defined(USG) || defined(STDC_HEADERS)
28 #define rindex strrchr
39 #define NLENGTH(direct) (strlen((direct)->d_name))
41 #define NLENGTH(direct) ((direct)->d_namlen)
54 /* Fake a return value. */
55 #define CLOSEDIR(d) (closedir (d), 0)
57 #define CLOSEDIR(d) closedir (d)
67 #define ISDIGIT(c) (isdigit ((unsigned char) (c)))
69 #define ISDIGIT(c) (isascii (c) && isdigit (c))
72 #if defined (HAVE_UNISTD_H)
76 #if defined (_POSIX_VERSION)
77 /* POSIX does not require that the d_ino field be present, and some
78 systems do not provide it. */
79 #define REAL_DIR_ENTRY(dp) 1
81 #define REAL_DIR_ENTRY(dp) ((dp)->d_ino != 0)
84 /* Which type of backup file names are generated. */
85 enum backup_type backup_type = none;
87 /* The extension added to file names to produce a simple (as opposed
88 to numbered) backup file name. */
89 char *simple_backup_suffix = "~";
93 static char *concat ();
94 char *find_backup_file_name ();
95 static char *make_version_name ();
96 static int max_backup_version ();
97 static int version_number ();
99 /* Return the name of the new backup file for file FILE,
100 allocated with malloc. Return 0 if out of memory.
101 FILE must not end with a '/' unless it is the root directory.
102 Do not call this function if backup_type == none. */
105 find_backup_file_name (file)
112 if (backup_type == simple)
113 return concat (file, simple_backup_suffix);
114 base_versions = concat (basename (file), ".~");
115 if (base_versions == 0)
117 dir = dirname (file);
120 free (base_versions);
123 highest_backup = max_backup_version (base_versions, dir);
124 free (base_versions);
126 if (backup_type == numbered_existing && highest_backup == 0)
127 return concat (file, simple_backup_suffix);
128 return make_version_name (file, highest_backup + 1);
131 /* Return the number of the highest-numbered backup file for file
132 FILE in directory DIR. If there are no numbered backups
133 of FILE in DIR, or an error occurs reading DIR, return 0.
134 FILE should already have ".~" appended to it. */
137 max_backup_version (file, dir)
144 int file_name_length;
146 dirp = opendir (dir);
151 file_name_length = strlen (file);
153 while ((dp = readdir (dirp)) != 0)
155 if (!REAL_DIR_ENTRY (dp) || NLENGTH (dp) <= file_name_length)
158 this_version = version_number (file, dp->d_name, file_name_length);
159 if (this_version > highest_version)
160 highest_version = this_version;
164 return highest_version;
167 /* Return a string, allocated with malloc, containing
168 "FILE.~VERSION~". Return 0 if out of memory. */
171 make_version_name (file, version)
177 backup_name = malloc (strlen (file) + 16);
178 if (backup_name == 0)
180 sprintf (backup_name, "%s.~%d~", file, version);
184 /* If BACKUP is a numbered backup of BASE, return its version number;
185 otherwise return 0. BASE_LENGTH is the length of BASE.
186 BASE should already have ".~" appended to it. */
189 version_number (base, backup, base_length)
198 if (!strncmp (base, backup, base_length) && ISDIGIT (backup[base_length]))
200 for (p = &backup[base_length]; ISDIGIT (*p); ++p)
201 version = version * 10 + *p - '0';
202 if (p[0] != '~' || p[1])
208 /* Return the newly-allocated concatenation of STR1 and STR2.
209 If out of memory, return 0. */
216 char str1_length = strlen (str1);
218 newstr = malloc (str1_length + strlen (str2) + 1);
221 strcpy (newstr, str1);
222 strcpy (newstr + str1_length, str2);