/* addext.c -- add an extension to a file name   Copyright 1990, 1997, 1998, 1999, 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> and Paul Eggert */#if HAVE_CONFIG_H# include <config.h>#endif#ifndef HAVE_DOS_FILE_NAMES# define HAVE_DOS_FILE_NAMES 0#endif#ifndef HAVE_LONG_FILE_NAMES# define HAVE_LONG_FILE_NAMES 0#endif#if HAVE_LIMITS_H# include <limits.h>#endif#ifndef _POSIX_NAME_MAX# define _POSIX_NAME_MAX 14#endif#include <sys/types.h>#if HAVE_STRING_H# include <string.h>#else# include <strings.h>#endif#if HAVE_UNISTD_H# include <unistd.h>#endif#include <errno.h>#ifndef errnoextern int errno;#endif#include "backupfile.h"#include "dirname.h"/* Append to FILENAME the extension EXT, unless the result would be too long,   in which case just append the character E.  */voidaddext (char *filename, char const *ext, int e){  char *s = base_name (filename);  size_t slen = base_len (s);  size_t extlen = strlen (ext);  size_t slen_max = HAVE_LONG_FILE_NAMES ? 255 : _POSIX_NAME_MAX;#if HAVE_PATHCONF && defined _PC_NAME_MAX  if (_POSIX_NAME_MAX < slen + extlen || HAVE_DOS_FILE_NAMES)    {      /* The new base name is long enough to require a pathconf check.  */      long name_max;      errno = 0;      if (s == filename)	name_max = pathconf (".", _PC_NAME_MAX);      else	{	  char c = *s;	  if (! ISSLASH (c))	    *s = 0;	  name_max = pathconf (filename, _PC_NAME_MAX);	  *s = c;	}      if (0 <= name_max || errno == 0)	slen_max = name_max == (size_t) name_max ? name_max : -1;    }#endif  if (HAVE_DOS_FILE_NAMES && slen_max <= 12)    {      /* Live within DOS's 8.3 limit.  */      char *dot = strchr (s, '.');      if (dot)	{	  slen -= dot + 1 - s;	  s = dot + 1;	  slen_max = 3;	}      else	slen_max = 8;      extlen = 9; /* Don't use EXT.  */    }  if (slen + extlen <= slen_max)    strcpy (s + slen, ext);  else    {      if (slen_max <= slen)	slen = slen_max - 1;      s[slen] = e;      s[slen + 1] = 0;    }}