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 Foundation,
16 Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, 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 */
39 # define dirent direct
40 # define NLENGTH(direct) ((direct)->d_namlen)
41 # ifdef HAVE_SYS_NDIR_H
42 # include <sys/ndir.h>
43 # endif /* HAVE_SYS_NDIR_H */
44 # ifdef HAVE_SYS_DIR_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))
66 # define IN_CTYPE_DOMAIN(c) 1
68 # define IN_CTYPE_DOMAIN(c) isascii(c)
71 #define ISDIGIT_LOCALE(c) (IN_CTYPE_DOMAIN (c) && isdigit (c))
73 /* ISDIGIT differs from ISDIGIT_LOCALE, as follows:
74 - Its arg may be any int or unsigned int; it need not be an unsigned char.
75 - It's guaranteed to evaluate its argument exactly once.
76 - It's typically faster.
77 Posix 1003.2-1992 section 2.5.2.1 page 50 lines 1556-1558 says that
78 only '0' through '9' are digits. Prefer ISDIGIT to ISDIGIT_LOCALE unless
79 it's important to use the locale's definition of `digit' even when the
80 host does not conform to Posix. */
81 #define ISDIGIT(c) ((unsigned) (c) - '0' <= 9)
83 #if defined (HAVE_UNISTD_H)
87 #if defined (_POSIX_VERSION)
88 /* POSIX does not require that the d_ino field be present, and some
89 systems do not provide it. */
90 # define REAL_DIR_ENTRY(dp) 1
92 # define REAL_DIR_ENTRY(dp) ((dp)->d_ino != 0)
95 /* Which type of backup file names are generated. */
96 enum backup_type backup_type = none;
98 /* The extension added to file names to produce a simple (as opposed
99 to numbered) backup file name. */
100 char *simple_backup_suffix = "~";
104 static char *concat ();
105 char *find_backup_file_name ();
106 static char *make_version_name ();
107 static int max_backup_version ();
108 static int version_number ();
110 /* Return the name of the new backup file for file FILE,
111 allocated with malloc. Return 0 if out of memory.
112 FILE must not end with a '/' unless it is the root directory.
113 Do not call this function if backup_type == none. */
116 find_backup_file_name (file)
123 if (backup_type == simple)
124 return concat (file, simple_backup_suffix);
125 base_versions = concat (basename (file), ".~");
126 if (base_versions == 0)
128 dir = dirname (file);
131 free (base_versions);
134 highest_backup = max_backup_version (base_versions, dir);
135 free (base_versions);
137 if (backup_type == numbered_existing && highest_backup == 0)
138 return concat (file, simple_backup_suffix);
139 return make_version_name (file, highest_backup + 1);
142 /* Return the number of the highest-numbered backup file for file
143 FILE in directory DIR. If there are no numbered backups
144 of FILE in DIR, or an error occurs reading DIR, return 0.
145 FILE should already have ".~" appended to it. */
148 max_backup_version (file, dir)
156 size_t file_name_length;
158 dirp = opendir (dir);
163 file_name_length = strlen (file);
165 while ((dp = readdir (dirp)) != 0)
167 if (!REAL_DIR_ENTRY (dp) || NLENGTH (dp) <= file_name_length)
170 this_version = version_number (file, dp->d_name, file_name_length);
171 if (this_version > highest_version)
172 highest_version = this_version;
176 return highest_version;
179 /* Return a string, allocated with malloc, containing
180 "FILE.~VERSION~". Return 0 if out of memory. */
183 make_version_name (file, version)
189 backup_name = malloc (strlen (file) + 16);
190 if (backup_name == 0)
192 sprintf (backup_name, "%s.~%d~", file, version);
196 /* If BACKUP is a numbered backup of BASE, return its version number;
197 otherwise return 0. BASE_LENGTH is the length of BASE.
198 BASE should already have ".~" appended to it. */
201 version_number (base, backup, base_length)
210 if (!strncmp (base, backup, base_length) && ISDIGIT (backup[base_length]))
212 for (p = &backup[base_length]; ISDIGIT (*p); ++p)
213 version = version * 10 + *p - '0';
214 if (p[0] != '~' || p[1])
220 /* Return the newly-allocated concatenation of STR1 and STR2.
221 If out of memory, return 0. */
229 int str1_length = strlen (str1);
231 newstr = malloc (str1_length + strlen (str2) + 1);
234 strcpy (newstr, str1);
235 strcpy (newstr + str1_length, str2);