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)
64 #define ISDIGIT(c) (isdigit ((unsigned char) (c)))
66 #define ISDIGIT(c) (isascii (c) && isdigit (c))
69 #if defined (HAVE_UNISTD_H)
73 #if defined (_POSIX_VERSION)
74 /* POSIX does not require that the d_ino field be present, and some
75 systems do not provide it. */
76 #define REAL_DIR_ENTRY(dp) 1
78 #define REAL_DIR_ENTRY(dp) ((dp)->d_ino != 0)
81 /* Which type of backup file names are generated. */
82 enum backup_type backup_type = none;
84 /* The extension added to file names to produce a simple (as opposed
85 to numbered) backup file name. */
86 char *simple_backup_suffix = "~";
90 static char *concat ();
91 char *find_backup_file_name ();
92 static char *make_version_name ();
93 static int max_backup_version ();
94 static int version_number ();
96 /* Return the name of the new backup file for file FILE,
97 allocated with malloc. Return 0 if out of memory.
98 FILE must not end with a '/' unless it is the root directory.
99 Do not call this function if backup_type == none. */
102 find_backup_file_name (file)
109 if (backup_type == simple)
110 return concat (file, simple_backup_suffix);
111 base_versions = concat (basename (file), ".~");
112 if (base_versions == 0)
114 dir = dirname (file);
117 free (base_versions);
120 highest_backup = max_backup_version (base_versions, dir);
121 free (base_versions);
123 if (backup_type == numbered_existing && highest_backup == 0)
124 return concat (file, simple_backup_suffix);
125 return make_version_name (file, highest_backup + 1);
128 /* Return the number of the highest-numbered backup file for file
129 FILE in directory DIR. If there are no numbered backups
130 of FILE in DIR, or an error occurs reading DIR, return 0.
131 FILE should already have ".~" appended to it. */
134 max_backup_version (file, dir)
141 int file_name_length;
143 dirp = opendir (dir);
148 file_name_length = strlen (file);
150 while ((dp = readdir (dirp)) != 0)
152 if (!REAL_DIR_ENTRY (dp) || NLENGTH (dp) <= file_name_length)
155 this_version = version_number (file, dp->d_name, file_name_length);
156 if (this_version > highest_version)
157 highest_version = this_version;
161 return highest_version;
164 /* Return a string, allocated with malloc, containing
165 "FILE.~VERSION~". Return 0 if out of memory. */
168 make_version_name (file, version)
174 backup_name = malloc (strlen (file) + 16);
175 if (backup_name == 0)
177 sprintf (backup_name, "%s.~%d~", file, version);
181 /* If BACKUP is a numbered backup of BASE, return its version number;
182 otherwise return 0. BASE_LENGTH is the length of BASE.
183 BASE should already have ".~" appended to it. */
186 version_number (base, backup, base_length)
195 if (!strncmp (base, backup, base_length) && ISDIGIT (backup[base_length]))
197 for (p = &backup[base_length]; ISDIGIT (*p); ++p)
198 version = version * 10 + *p - '0';
199 if (p[0] != '~' || p[1])
205 /* Return the newly-allocated concatenation of STR1 and STR2.
206 If out of memory, return 0. */
213 char str1_length = strlen (str1);
215 newstr = malloc (str1_length + strlen (str2) + 1);
218 strcpy (newstr, str1);
219 strcpy (newstr + str1_length, str2);