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. */
27 #include <sys/types.h>
28 #include "backupfile.h"
29 #if defined(STDC_HEADERS) || defined(HAVE_STRING_H)
35 #define rindex strrchr
43 #define NLENGTH(direct) (strlen((direct)->d_name))
44 #else /* not HAVE_DIRENT_H */
46 #define NLENGTH(direct) ((direct)->d_namlen)
47 #ifdef HAVE_SYS_NDIR_H
49 #endif /* HAVE_SYS_NDIR_H */
52 #endif /* HAVE_SYS_DIR_H */
55 #endif /* HAVE_NDIR_H */
56 #endif /* HAVE_DIRENT_H */
59 /* Fake a return value. */
60 #define CLOSEDIR(d) (closedir (d), 0)
62 #define CLOSEDIR(d) closedir (d)
71 #if !defined (isascii) || defined (STDC_HEADERS)
76 #define ISDIGIT(c) (isascii ((unsigned char ) c) \
77 && isdigit ((unsigned char) (c)))
79 #if defined (HAVE_UNISTD_H)
83 #if defined (_POSIX_VERSION)
84 /* POSIX does not require that the d_ino field be present, and some
85 systems do not provide it. */
86 #define REAL_DIR_ENTRY(dp) 1
88 #define REAL_DIR_ENTRY(dp) ((dp)->d_ino != 0)
91 /* Which type of backup file names are generated. */
92 enum backup_type backup_type = none;
94 /* The extension added to file names to produce a simple (as opposed
95 to numbered) backup file name. */
96 char *simple_backup_suffix = "~";
100 static char *concat ();
101 char *find_backup_file_name ();
102 static char *make_version_name ();
103 static int max_backup_version ();
104 static int version_number ();
106 /* Return the name of the new backup file for file FILE,
107 allocated with malloc. Return 0 if out of memory.
108 FILE must not end with a '/' unless it is the root directory.
109 Do not call this function if backup_type == none. */
112 find_backup_file_name (file)
119 if (backup_type == simple)
120 return concat (file, simple_backup_suffix);
121 base_versions = concat (basename (file), ".~");
122 if (base_versions == 0)
124 dir = dirname (file);
127 free (base_versions);
130 highest_backup = max_backup_version (base_versions, dir);
131 free (base_versions);
133 if (backup_type == numbered_existing && highest_backup == 0)
134 return concat (file, simple_backup_suffix);
135 return make_version_name (file, highest_backup + 1);
138 /* Return the number of the highest-numbered backup file for file
139 FILE in directory DIR. If there are no numbered backups
140 of FILE in DIR, or an error occurs reading DIR, return 0.
141 FILE should already have ".~" appended to it. */
144 max_backup_version (file, dir)
151 int file_name_length;
153 dirp = opendir (dir);
158 file_name_length = strlen (file);
160 while ((dp = readdir (dirp)) != 0)
162 if (!REAL_DIR_ENTRY (dp) || NLENGTH (dp) <= file_name_length)
165 this_version = version_number (file, dp->d_name, file_name_length);
166 if (this_version > highest_version)
167 highest_version = this_version;
171 return highest_version;
174 /* Return a string, allocated with malloc, containing
175 "FILE.~VERSION~". Return 0 if out of memory. */
178 make_version_name (file, version)
184 backup_name = malloc (strlen (file) + 16);
185 if (backup_name == 0)
187 sprintf (backup_name, "%s.~%d~", file, version);
191 /* If BACKUP is a numbered backup of BASE, return its version number;
192 otherwise return 0. BASE_LENGTH is the length of BASE.
193 BASE should already have ".~" appended to it. */
196 version_number (base, backup, base_length)
205 if (!strncmp (base, backup, base_length) && ISDIGIT (backup[base_length]))
207 for (p = &backup[base_length]; ISDIGIT (*p); ++p)
208 version = version * 10 + *p - '0';
209 if (p[0] != '~' || p[1])
215 /* Return the newly-allocated concatenation of STR1 and STR2.
216 If out of memory, return 0. */
223 int str1_length = strlen (str1);
225 newstr = malloc (str1_length + strlen (str2) + 1);
228 strcpy (newstr, str1);
229 strcpy (newstr + str1_length, str2);