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"
37 #define NLENGTH(direct) (strlen((direct)->d_name))
38 #else /* not HAVE_DIRENT_H */
40 #define NLENGTH(direct) ((direct)->d_namlen)
41 #ifdef HAVE_SYS_NDIR_H
43 #endif /* HAVE_SYS_NDIR_H */
46 #endif /* HAVE_SYS_DIR_H */
49 #endif /* HAVE_NDIR_H */
50 #endif /* HAVE_DIRENT_H */
53 /* Fake a return value. */
54 #define CLOSEDIR(d) (closedir (d), 0)
56 #define CLOSEDIR(d) closedir (d)
65 #if defined (STDC_HEADERS) || (!defined (isascii) && !defined (HAVE_ISASCII))
68 #define ISASCII(c) isascii(c)
71 #define ISDIGIT(c) (ISASCII ((unsigned char) (c)) \
72 && isdigit ((unsigned char) (c)))
74 #if defined (HAVE_UNISTD_H)
78 #if defined (_POSIX_VERSION)
79 /* POSIX does not require that the d_ino field be present, and some
80 systems do not provide it. */
81 #define REAL_DIR_ENTRY(dp) 1
83 #define REAL_DIR_ENTRY(dp) ((dp)->d_ino != 0)
86 /* Which type of backup file names are generated. */
87 enum backup_type backup_type = none;
89 /* The extension added to file names to produce a simple (as opposed
90 to numbered) backup file name. */
91 char *simple_backup_suffix = "~";
95 static char *concat ();
96 char *find_backup_file_name ();
97 static char *make_version_name ();
98 static int max_backup_version ();
99 static int version_number ();
101 /* Return the name of the new backup file for file FILE,
102 allocated with malloc. Return 0 if out of memory.
103 FILE must not end with a '/' unless it is the root directory.
104 Do not call this function if backup_type == none. */
107 find_backup_file_name (file)
114 if (backup_type == simple)
115 return concat (file, simple_backup_suffix);
116 base_versions = concat (basename (file), ".~");
117 if (base_versions == 0)
119 dir = dirname (file);
122 free (base_versions);
125 highest_backup = max_backup_version (base_versions, dir);
126 free (base_versions);
128 if (backup_type == numbered_existing && highest_backup == 0)
129 return concat (file, simple_backup_suffix);
130 return make_version_name (file, highest_backup + 1);
133 /* Return the number of the highest-numbered backup file for file
134 FILE in directory DIR. If there are no numbered backups
135 of FILE in DIR, or an error occurs reading DIR, return 0.
136 FILE should already have ".~" appended to it. */
139 max_backup_version (file, dir)
146 int file_name_length;
148 dirp = opendir (dir);
153 file_name_length = strlen (file);
155 while ((dp = readdir (dirp)) != 0)
157 if (!REAL_DIR_ENTRY (dp) || NLENGTH (dp) <= file_name_length)
160 this_version = version_number (file, dp->d_name, file_name_length);
161 if (this_version > highest_version)
162 highest_version = this_version;
166 return highest_version;
169 /* Return a string, allocated with malloc, containing
170 "FILE.~VERSION~". Return 0 if out of memory. */
173 make_version_name (file, version)
179 backup_name = malloc (strlen (file) + 16);
180 if (backup_name == 0)
182 sprintf (backup_name, "%s.~%d~", file, version);
186 /* If BACKUP is a numbered backup of BASE, return its version number;
187 otherwise return 0. BASE_LENGTH is the length of BASE.
188 BASE should already have ".~" appended to it. */
191 version_number (base, backup, base_length)
200 if (!strncmp (base, backup, base_length) && ISDIGIT (backup[base_length]))
202 for (p = &backup[base_length]; ISDIGIT (*p); ++p)
203 version = version * 10 + *p - '0';
204 if (p[0] != '~' || p[1])
210 /* Return the newly-allocated concatenation of STR1 and STR2.
211 If out of memory, return 0. */
218 int str1_length = strlen (str1);
220 newstr = malloc (str1_length + strlen (str2) + 1);
223 strcpy (newstr, str1);
224 strcpy (newstr + str1_length, str2);