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)
28 #define rindex strrchr
33 #if defined(DIRENT) || defined(_POSIX_VERSION)
35 #define NLENGTH(direct) (strlen((direct)->d_name))
36 #else /* not (DIRENT or _POSIX_VERSION) */
38 #define NLENGTH(direct) ((direct)->d_namlen)
48 #endif /* DIRENT or _POSIX_VERSION */
51 /* Fake a return value. */
52 #define CLOSEDIR(d) (closedir (d), 0)
54 #define CLOSEDIR(d) closedir (d)
63 #if !defined (isascii) || defined (STDC_HEADERS)
68 #define ISDIGIT(c) (isascii ((unsigned char ) c) \
69 && isdigit ((unsigned char) (c)))
71 #if defined (HAVE_UNISTD_H)
75 #if defined (_POSIX_VERSION)
76 /* POSIX does not require that the d_ino field be present, and some
77 systems do not provide it. */
78 #define REAL_DIR_ENTRY(dp) 1
80 #define REAL_DIR_ENTRY(dp) ((dp)->d_ino != 0)
83 /* Which type of backup file names are generated. */
84 enum backup_type backup_type = none;
86 /* The extension added to file names to produce a simple (as opposed
87 to numbered) backup file name. */
88 char *simple_backup_suffix = "~";
92 static char *concat ();
93 char *find_backup_file_name ();
94 static char *make_version_name ();
95 static int max_backup_version ();
96 static int version_number ();
98 /* Return the name of the new backup file for file FILE,
99 allocated with malloc. Return 0 if out of memory.
100 FILE must not end with a '/' unless it is the root directory.
101 Do not call this function if backup_type == none. */
104 find_backup_file_name (file)
111 if (backup_type == simple)
112 return concat (file, simple_backup_suffix);
113 base_versions = concat (basename (file), ".~");
114 if (base_versions == 0)
116 dir = dirname (file);
119 free (base_versions);
122 highest_backup = max_backup_version (base_versions, dir);
123 free (base_versions);
125 if (backup_type == numbered_existing && highest_backup == 0)
126 return concat (file, simple_backup_suffix);
127 return make_version_name (file, highest_backup + 1);
130 /* Return the number of the highest-numbered backup file for file
131 FILE in directory DIR. If there are no numbered backups
132 of FILE in DIR, or an error occurs reading DIR, return 0.
133 FILE should already have ".~" appended to it. */
136 max_backup_version (file, dir)
143 int file_name_length;
145 dirp = opendir (dir);
150 file_name_length = strlen (file);
152 while ((dp = readdir (dirp)) != 0)
154 if (!REAL_DIR_ENTRY (dp) || NLENGTH (dp) <= file_name_length)
157 this_version = version_number (file, dp->d_name, file_name_length);
158 if (this_version > highest_version)
159 highest_version = this_version;
163 return highest_version;
166 /* Return a string, allocated with malloc, containing
167 "FILE.~VERSION~". Return 0 if out of memory. */
170 make_version_name (file, version)
176 backup_name = malloc (strlen (file) + 16);
177 if (backup_name == 0)
179 sprintf (backup_name, "%s.~%d~", file, version);
183 /* If BACKUP is a numbered backup of BASE, return its version number;
184 otherwise return 0. BASE_LENGTH is the length of BASE.
185 BASE should already have ".~" appended to it. */
188 version_number (base, backup, base_length)
197 if (!strncmp (base, backup, base_length) && ISDIGIT (backup[base_length]))
199 for (p = &backup[base_length]; ISDIGIT (*p); ++p)
200 version = version * 10 + *p - '0';
201 if (p[0] != '~' || p[1])
207 /* Return the newly-allocated concatenation of STR1 and STR2.
208 If out of memory, return 0. */
215 char str1_length = strlen (str1);
217 newstr = malloc (str1_length + strlen (str2) + 1);
220 strcpy (newstr, str1);
221 strcpy (newstr + str1_length, str2);