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BACKUPFI.C
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C/C++ Source or Header
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1990-06-07
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6KB
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254 lines
/* backupfile.c -- make Emacs style backup file names
Copyright (C) 1990 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 1, 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; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
/* David MacKenzie <djm@ai.mit.edu>.
Some algorithms adapted from GNU Emacs. */
#include <ctype.h>
#include <sys/types.h>
#include "backupfile.h"
#if defined(USG) || defined(_POSIX_SOURCE)
#define index strchr
#define rindex strrchr
#include <string.h>
#else
#include <strings.h>
#endif
#ifdef DIRENT
#include <dirent.h>
#define direct dirent
#define NLENGTH(direct) (strlen((direct)->d_name))
#else
#define NLENGTH(direct) ((direct)->d_namlen)
#ifdef USG
#ifdef SYSNDIR
#include <sys/ndir.h>
#else
#include <ndir.h>
#endif
#else /* must be BSD */
#include <sys/dir.h>
#endif
#endif
#ifdef STDC_HEADERS
#include <stdlib.h>
#define ISDIGIT(c) (isdigit ((unsigned char) (c)))
#else
#define ISDIGIT(c) (isascii (c) && isdigit (c))
char *malloc ();
#endif
/* Which type of backup file names are generated. */
enum backup_type backup_type = none;
/* The extension added to file names to produce a simple (as opposed
to numbered) backup file name. */
char *simple_backup_suffix = "~";
static char *basename ();
static char *concat ();
static char *copystring ();
static char *dirname ();
char *find_backup_file_name ();
static char *make_version_name ();
static int max_backup_version ();
static int version_number ();
/* 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 (file)
char *file;
{
char *dir;
char *base_versions;
int highest_backup;
if (backup_type == simple)
return concat (file, simple_backup_suffix);
base_versions = concat (basename (file), ".~");
if (base_versions == 0)
return 0;
dir = dirname (file);
if (dir == 0)
{
free (base_versions);
return 0;
}
highest_backup = max_backup_version (base_versions, dir);
free (base_versions);
free (dir);
if (backup_type == numbered_existing && highest_backup == 0)
return concat (file, simple_backup_suffix);
return make_version_name (file, highest_backup + 1);
}
/* 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, return 0.
FILE should already have ".~" appended to it. */
static int
max_backup_version (file, dir)
char *file, *dir;
{
DIR *dirp;
struct direct *dp;
int highest_version;
int this_version;
int file_name_length;
dirp = opendir (dir);
if (!dirp)
return 0;
highest_version = 0;
file_name_length = strlen (file);
while ((dp = readdir (dirp)) != 0)
{
if (dp->d_ino == 0 || NLENGTH (dp) <= file_name_length)
continue;
this_version = version_number (file, dp->d_name, file_name_length);
if (this_version > highest_version)
highest_version = this_version;
}
closedir (dirp);
return highest_version;
}
/* Return a string, allocated with malloc, containing
"FILE.~VERSION~". Return 0 if out of memory. */
static char *
make_version_name (file, version)
char *file;
int version;
{
char *backup_name;
backup_name = malloc (strlen (file) + 16);
if (backup_name == 0)
return 0;
sprintf (backup_name, "%s.~%d~", file, version);
return backup_name;
}
/* If BACKUP is a numbered backup of BASE, return its version number;
otherwise return 0. BASE_LENGTH is the length of BASE.
BASE should already have ".~" appended to it. */
static int
version_number (base, backup, base_length)
char *base;
char *backup;
int base_length;
{
int version;
char *p;
version = 0;
if (!strncmp (base, backup, base_length) && ISDIGIT (backup[base_length]))
{
for (p = &backup[base_length]; ISDIGIT (*p); ++p)
version = version * 10 + *p - '0';
if (p[0] != '~' || p[1])
version = 0;
}
return version;
}
/* Return the leading directories part of PATH,
allocated with malloc. If out of memory, return 0. */
static char *
dirname (path)
char *path;
{
char *newpath;
char *slash;
char *scan;
slash = rindex (path, '/');
if (slash == 0)
return copystring (".");
newpath = malloc (strlen (path) + 1);
if (newpath == 0)
return 0;
strcpy (newpath, path);
slash += newpath - path;
/* Remove any trailing slashes and final element. */
for (scan = slash; scan > newpath && *scan == '/'; --scan)
/* Do nothing. */ ;
if (scan > newpath)
scan[1] = 0;
return newpath;
}
/* Return NAME with any leading path stripped off. */
static char *
basename (name)
char *name;
{
char *base;
base = rindex (name, '/');
return base ? base + 1 : name;
}
/* Return the newly-allocated concatenation of STR1 and STR2.
If out of memory, return 0. */
static char *
concat (str1, str2)
char *str1, *str2;
{
char *newstr;
char str1_length = strlen (str1);
newstr = malloc (str1_length + strlen (str2) + 1);
if (newstr == 0)
return 0;
strcpy (newstr, str1);
strcpy (newstr + str1_length, str2);
return newstr;
}
/* Return a newly allocated copy of STR. */
static char *
copystring (str)
char *str;
{
char *newstr;
newstr = malloc (strlen (str) + 1);
if (newstr == 0)
return 0;
strcpy (newstr, str);
return newstr;
}