1 /* backupfile.c -- make Emacs style backup file names
2 Copyright (C) 1990-1997, 1998, 1999, 2000 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; see the file COPYING.
16 If not, write to the Free Software Foundation,
17 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
19 /* Written by David MacKenzie <djm@gnu.ai.mit.edu>.
20 Some algorithms adapted from GNU Emacs. */
27 #include <backupfile.h>
30 #include <sys/types.h>
39 # define NLENGTH(direct) strlen ((direct)->d_name)
41 # define dirent direct
42 # define NLENGTH(direct) ((size_t) (direct)->d_namlen)
44 # include <sys/ndir.h>
55 /* Fake a return value. */
56 # define CLOSEDIR(d) (closedir (d), 0)
58 # define CLOSEDIR(d) closedir (d)
67 #ifndef HAVE_DECL_GETENV
68 "this configure-time declaration test was not run"
74 char *base_name PARAMS ((char const *));
76 #if HAVE_DIRENT_H || HAVE_NDIR_H || HAVE_SYS_DIR_H || HAVE_SYS_NDIR_H
88 /* Upper bound on the string length of an integer converted to string.
89 302 / 1000 is ceil (log10 (2.0)). Subtract 1 for the sign bit;
90 add 1 for integer division truncation; add 1 more for a minus sign. */
91 #define INT_STRLEN_BOUND(t) ((sizeof (t) * CHAR_BIT - 1) * 302 / 1000 + 2)
93 /* ISDIGIT differs from isdigit, as follows:
94 - Its arg may be any int or unsigned int; it need not be an unsigned char.
95 - It's guaranteed to evaluate its argument exactly once.
96 - It's typically faster.
97 Posix 1003.2-1992 section 2.5.2.1 page 50 lines 1556-1558 says that
98 only '0' through '9' are digits. Prefer ISDIGIT to isdigit unless
99 it's important to use the locale's definition of `digit' even when the
100 host does not conform to Posix. */
101 #define ISDIGIT(c) ((unsigned) (c) - '0' <= 9)
104 # define REAL_DIR_ENTRY(dp) ((dp)->d_ino != 0)
106 # define REAL_DIR_ENTRY(dp) 1
109 /* The extension added to file names to produce a simple (as opposed
110 to numbered) backup file name. */
111 const char *simple_backup_suffix = "~";
113 static int max_backup_version PARAMS ((const char *, const char *));
114 static int version_number PARAMS ((const char *, const char *, size_t));
116 /* Return the name of the new backup file for file FILE,
117 allocated with malloc. Return 0 if out of memory.
118 FILE must not end with a '/' unless it is the root directory.
119 Do not call this function if backup_type == none. */
122 find_backup_file_name (const char *file, enum backup_type backup_type)
124 size_t backup_suffix_size_max;
125 size_t file_len = strlen (file);
126 size_t numbered_suffix_size_max = INT_STRLEN_BOUND (int) + 4;
128 const char *suffix = simple_backup_suffix;
130 /* Allow room for simple or `.~N~' backups. */
131 backup_suffix_size_max = strlen (simple_backup_suffix) + 1;
132 if (HAVE_DIR && backup_suffix_size_max < numbered_suffix_size_max)
133 backup_suffix_size_max = numbered_suffix_size_max;
135 s = malloc (file_len + backup_suffix_size_max + numbered_suffix_size_max);
141 if (backup_type != simple)
144 size_t dir_len = base_name (s) - s;
146 strcpy (s + dir_len, ".");
147 highest_backup = max_backup_version (file + dir_len, s);
148 if (! (backup_type == numbered_existing && highest_backup == 0))
150 char *numbered_suffix = s + (file_len + backup_suffix_size_max);
151 sprintf (numbered_suffix, ".~%d~", highest_backup + 1);
152 suffix = numbered_suffix;
156 #endif /* HAVE_DIR */
158 addext (s, suffix, '~');
165 /* Return the number of the highest-numbered backup file for file
166 FILE in directory DIR. If there are no numbered backups
167 of FILE in DIR, or an error occurs reading DIR, return 0.
171 max_backup_version (const char *file, const char *dir)
177 size_t file_name_length;
179 dirp = opendir (dir);
184 file_name_length = strlen (file);
186 while ((dp = readdir (dirp)) != 0)
188 if (!REAL_DIR_ENTRY (dp) || NLENGTH (dp) < file_name_length + 4)
191 this_version = version_number (file, dp->d_name, file_name_length);
192 if (this_version > highest_version)
193 highest_version = this_version;
197 return highest_version;
200 /* If BACKUP is a numbered backup of BASE, return its version number;
201 otherwise return 0. BASE_LENGTH is the length of BASE.
205 version_number (const char *base, const char *backup, size_t base_length)
211 if (strncmp (base, backup, base_length) == 0
212 && backup[base_length] == '.'
213 && backup[base_length + 1] == '~')
215 for (p = &backup[base_length + 2]; ISDIGIT (*p); ++p)
216 version = version * 10 + *p - '0';
217 if (p[0] != '~' || p[1])
222 #endif /* HAVE_DIR */
224 static const char * const backup_args[] =
226 /* In a series of synonyms, present the most meaning full first, so
227 that argmatch_valid be more readable. */
235 static const enum backup_type backup_types[] =
239 numbered_existing, numbered_existing,
243 /* Return the type of backup specified by VERSION.
244 If VERSION is NULL or the empty string, return numbered_existing.
245 If VERSION is invalid or ambiguous, fail with a diagnostic appropriate
246 for the specified CONTEXT. Unambiguous abbreviations are accepted. */
249 get_version (const char *context, const char *version)
251 if (version == 0 || *version == 0)
252 return numbered_existing;
254 return XARGMATCH (context, version, backup_args, backup_types);
258 /* Return the type of backup specified by VERSION.
259 If VERSION is NULL, use the value of the envvar VERSION_CONTROL.
260 If the specified string is invalid or ambiguous, fail with a diagnostic
261 appropriate for the specified CONTEXT.
262 Unambiguous abbreviations are accepted. */
265 xget_version (const char *context, const char *version)
267 if (version && *version)
268 return get_version (context, version);
270 return get_version ("$VERSION_CONTROL", getenv ("VERSION_CONTROL"));