279 lines
7.5 KiB
C
279 lines
7.5 KiB
C
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/* backupfile.c -- make Emacs style backup file names
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Copyright 1990,91,92,93,94,95,96,97,98,99,2000, 2001 Free Software
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Foundation, Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; see the file COPYING.
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If not, write to the Free Software Foundation,
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59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
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/* Written by David MacKenzie <djm@gnu.ai.mit.edu>.
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Some algorithms adapted from GNU Emacs. */
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#if HAVE_CONFIG_H
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# include <config.h>
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#endif
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#include <stdio.h>
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#include <sys/types.h>
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#if HAVE_STRING_H
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# include <string.h>
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#else
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# include <strings.h>
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#endif
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#if HAVE_DIRENT_H
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# include <dirent.h>
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# define NLENGTH(direct) strlen ((direct)->d_name)
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#else
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# define dirent direct
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# define NLENGTH(direct) ((size_t) (direct)->d_namlen)
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# if HAVE_SYS_NDIR_H
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# include <sys/ndir.h>
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# endif
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# if HAVE_SYS_DIR_H
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# include <sys/dir.h>
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# endif
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# if HAVE_NDIR_H
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# include <ndir.h>
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# endif
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#endif
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#if CLOSEDIR_VOID
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/* Fake a return value. */
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# define CLOSEDIR(d) (closedir (d), 0)
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#else
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# define CLOSEDIR(d) closedir (d)
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#endif
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#if HAVE_STDLIB_H
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# include <stdlib.h>
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#endif
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#ifndef HAVE_DECL_GETENV
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"this configure-time declaration test was not run"
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#endif
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#if !HAVE_DECL_GETENV
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char *getenv ();
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#endif
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#ifndef HAVE_DECL_MALLOC
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"this configure-time declaration test was not run"
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#endif
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#if !HAVE_DECL_MALLOC
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char *malloc ();
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#endif
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#if HAVE_DIRENT_H || HAVE_NDIR_H || HAVE_SYS_DIR_H || HAVE_SYS_NDIR_H
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# define HAVE_DIR 1
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#else
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# define HAVE_DIR 0
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#endif
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#if HAVE_LIMITS_H
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# include <limits.h>
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#endif
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#ifndef CHAR_BIT
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# define CHAR_BIT 8
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#endif
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/* Upper bound on the string length of an integer converted to string.
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302 / 1000 is ceil (log10 (2.0)). Subtract 1 for the sign bit;
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add 1 for integer division truncation; add 1 more for a minus sign. */
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#define INT_STRLEN_BOUND(t) ((sizeof (t) * CHAR_BIT - 1) * 302 / 1000 + 2)
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/* ISDIGIT differs from isdigit, as follows:
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- Its arg may be any int or unsigned int; it need not be an unsigned char.
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- It's guaranteed to evaluate its argument exactly once.
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- It's typically faster.
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Posix 1003.2-1992 section 2.5.2.1 page 50 lines 1556-1558 says that
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only '0' through '9' are digits. Prefer ISDIGIT to isdigit unless
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it's important to use the locale's definition of `digit' even when the
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host does not conform to Posix. */
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#define ISDIGIT(c) ((unsigned) (c) - '0' <= 9)
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#if D_INO_IN_DIRENT
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# define REAL_DIR_ENTRY(dp) ((dp)->d_ino != 0)
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#else
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# define REAL_DIR_ENTRY(dp) 1
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#endif
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#include "argmatch.h"
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#include "backupfile.h"
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#include "dirname.h"
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/* The extension added to file names to produce a simple (as opposed
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to numbered) backup file name. */
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const char *simple_backup_suffix = "~";
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static int max_backup_version PARAMS ((const char *, const char *));
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static int version_number PARAMS ((const char *, const char *, size_t));
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/* Return the name of the new backup file for file FILE,
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allocated with malloc. Return 0 if out of memory.
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FILE must not end with a '/' unless it is the root directory.
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Do not call this function if backup_type == none. */
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char *
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find_backup_file_name (const char *file, enum backup_type backup_type)
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{
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size_t backup_suffix_size_max;
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size_t file_len = strlen (file);
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size_t numbered_suffix_size_max = INT_STRLEN_BOUND (int) + 4;
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char *s;
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const char *suffix = simple_backup_suffix;
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/* Allow room for simple or `.~N~' backups. */
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backup_suffix_size_max = strlen (simple_backup_suffix) + 1;
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if (HAVE_DIR && backup_suffix_size_max < numbered_suffix_size_max)
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backup_suffix_size_max = numbered_suffix_size_max;
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s = malloc (file_len + 1
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+ backup_suffix_size_max + numbered_suffix_size_max);
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if (s)
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{
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#if HAVE_DIR
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if (backup_type != simple)
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{
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int highest_backup;
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size_t dirlen = dir_len (file);
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memcpy (s, file, dirlen);
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if (dirlen == FILESYSTEM_PREFIX_LEN (file))
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s[dirlen++] = '.';
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s[dirlen] = '\0';
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highest_backup = max_backup_version (base_name (file), s);
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if (! (backup_type == numbered_existing && highest_backup == 0))
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{
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char *numbered_suffix = s + (file_len + backup_suffix_size_max);
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sprintf (numbered_suffix, ".~%d~", highest_backup + 1);
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suffix = numbered_suffix;
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}
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}
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#endif /* HAVE_DIR */
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strcpy (s, file);
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addext (s, suffix, '~');
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}
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return s;
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}
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#if HAVE_DIR
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/* Return the number of the highest-numbered backup file for file
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FILE in directory DIR. If there are no numbered backups
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of FILE in DIR, or an error occurs reading DIR, return 0.
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*/
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static int
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max_backup_version (const char *file, const char *dir)
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{
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DIR *dirp;
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struct dirent *dp;
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int highest_version;
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int this_version;
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size_t file_name_length;
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dirp = opendir (dir);
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if (!dirp)
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return 0;
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highest_version = 0;
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file_name_length = base_len (file);
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while ((dp = readdir (dirp)) != 0)
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{
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if (!REAL_DIR_ENTRY (dp) || NLENGTH (dp) < file_name_length + 4)
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continue;
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this_version = version_number (file, dp->d_name, file_name_length);
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if (this_version > highest_version)
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highest_version = this_version;
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}
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if (CLOSEDIR (dirp))
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return 0;
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return highest_version;
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}
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/* If BACKUP is a numbered backup of BASE, return its version number;
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otherwise return 0. BASE_LENGTH is the length of BASE.
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*/
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static int
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version_number (const char *base, const char *backup, size_t base_length)
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{
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int version;
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const char *p;
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version = 0;
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if (strncmp (base, backup, base_length) == 0
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&& backup[base_length] == '.'
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&& backup[base_length + 1] == '~')
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{
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for (p = &backup[base_length + 2]; ISDIGIT (*p); ++p)
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version = version * 10 + *p - '0';
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if (p[0] != '~' || p[1])
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version = 0;
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}
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return version;
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}
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#endif /* HAVE_DIR */
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static const char * const backup_args[] =
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{
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/* In a series of synonyms, present the most meaning full first, so
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that argmatch_valid be more readable. */
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"none", "off",
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"simple", "never",
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"existing", "nil",
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"numbered", "t",
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0
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};
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static const enum backup_type backup_types[] =
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{
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none, none,
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simple, simple,
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numbered_existing, numbered_existing,
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numbered, numbered
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};
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/* Return the type of backup specified by VERSION.
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If VERSION is NULL or the empty string, return numbered_existing.
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If VERSION is invalid or ambiguous, fail with a diagnostic appropriate
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for the specified CONTEXT. Unambiguous abbreviations are accepted. */
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enum backup_type
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get_version (const char *context, const char *version)
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{
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if (version == 0 || *version == 0)
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return numbered_existing;
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else
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return XARGMATCH (context, version, backup_args, backup_types);
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}
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/* Return the type of backup specified by VERSION.
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If VERSION is NULL, use the value of the envvar VERSION_CONTROL.
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If the specified string is invalid or ambiguous, fail with a diagnostic
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appropriate for the specified CONTEXT.
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Unambiguous abbreviations are accepted. */
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enum backup_type
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xget_version (const char *context, const char *version)
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{
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if (version && *version)
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return get_version (context, version);
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else
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return get_version ("$VERSION_CONTROL", getenv ("VERSION_CONTROL"));
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}
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