freebsd-dev/contrib/tar/lib/backupfile.c

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