ref: ed3a576e8b103032b659febc5d3c62565c9cf7d7
dir: /sys/src/ape/cmd/patch/backupfile.c/
/* backupfile.c -- make Emacs style backup file names
Copyright (C) 1990,1991,1992,1993,1995,1997 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 <argmatch.h>
#include <backupfile.h>
#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 STDC_HEADERS
# include <stdlib.h>
#else
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
/* 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. */
const char *simple_backup_suffix = ".orig";
static int max_backup_version __BACKUPFILE_P ((const char *, const char *));
static int version_number __BACKUPFILE_P ((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 (file)
const char *file;
{
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 + backup_suffix_size_max + numbered_suffix_size_max);
if (s)
{
strcpy (s, file);
#if HAVE_DIR
if (backup_type != simple)
{
int highest_backup;
size_t dir_len = base_name (s) - s;
strcpy (s + dir_len, ".");
highest_backup = max_backup_version (file + dir_len, 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;
}
strcpy (s, file);
}
#endif /* HAVE_DIR */
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 (file, dir)
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 = strlen (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 (base, backup, base_length)
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[] =
{
"never", "simple", "nil", "existing", "t", "numbered", 0
};
static const enum backup_type backup_types[] =
{
simple, simple, numbered_existing, numbered_existing, numbered, numbered
};
/* Return the type of backup indicated by VERSION.
Unique abbreviations are accepted. */
enum backup_type
get_version (version)
const char *version;
{
int i;
if (version == 0 || *version == 0)
return numbered_existing;
i = argmatch (version, backup_args);
if (i < 0)
{
invalid_arg ("version control type", version, i);
exit (2);
}
return backup_types[i];
}