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)
67 #define ISDIGIT(c) (isascii ((unsigned char ) c) \
68 && isdigit ((unsigned char) (c)))
70 #if defined (HAVE_UNISTD_H)
74 #if defined (_POSIX_VERSION)
75 /* POSIX does not require that the d_ino field be present, and some
76 systems do not provide it. */
77 #define REAL_DIR_ENTRY(dp) 1
79 #define REAL_DIR_ENTRY(dp) ((dp)->d_ino != 0)
82 /* Which type of backup file names are generated. */
83 enum backup_type backup_type = none;
85 /* The extension added to file names to produce a simple (as opposed
86 to numbered) backup file name. */
87 char *simple_backup_suffix = "~";
91 static char *concat ();
92 char *find_backup_file_name ();
93 static char *make_version_name ();
94 static int max_backup_version ();
95 static int version_number ();
97 /* Return the name of the new backup file for file FILE,
98 allocated with malloc. Return 0 if out of memory.
99 FILE must not end with a '/' unless it is the root directory.
100 Do not call this function if backup_type == none. */
103 find_backup_file_name (file)
110 if (backup_type == simple)
111 return concat (file, simple_backup_suffix);
112 base_versions = concat (basename (file), ".~");
113 if (base_versions == 0)
115 dir = dirname (file);
118 free (base_versions);
121 highest_backup = max_backup_version (base_versions, dir);
122 free (base_versions);
124 if (backup_type == numbered_existing && highest_backup == 0)
125 return concat (file, simple_backup_suffix);
126 return make_version_name (file, highest_backup + 1);
129 /* Return the number of the highest-numbered backup file for file
130 FILE in directory DIR. If there are no numbered backups
131 of FILE in DIR, or an error occurs reading DIR, return 0.
132 FILE should already have ".~" appended to it. */
135 max_backup_version (file, dir)
142 int file_name_length;
144 dirp = opendir (dir);
149 file_name_length = strlen (file);
151 while ((dp = readdir (dirp)) != 0)
153 if (!REAL_DIR_ENTRY (dp) || NLENGTH (dp) <= file_name_length)
156 this_version = version_number (file, dp->d_name, file_name_length);
157 if (this_version > highest_version)
158 highest_version = this_version;
162 return highest_version;
165 /* Return a string, allocated with malloc, containing
166 "FILE.~VERSION~". Return 0 if out of memory. */
169 make_version_name (file, version)
175 backup_name = malloc (strlen (file) + 16);
176 if (backup_name == 0)
178 sprintf (backup_name, "%s.~%d~", file, version);
182 /* If BACKUP is a numbered backup of BASE, return its version number;
183 otherwise return 0. BASE_LENGTH is the length of BASE.
184 BASE should already have ".~" appended to it. */
187 version_number (base, backup, base_length)
196 if (!strncmp (base, backup, base_length) && ISDIGIT (backup[base_length]))
198 for (p = &backup[base_length]; ISDIGIT (*p); ++p)
199 version = version * 10 + *p - '0';
200 if (p[0] != '~' || p[1])
206 /* Return the newly-allocated concatenation of STR1 and STR2.
207 If out of memory, return 0. */
214 char str1_length = strlen (str1);
216 newstr = malloc (str1_length + strlen (str2) + 1);
219 strcpy (newstr, str1);
220 strcpy (newstr + str1_length, str2);