1/* addext.c -- add an extension to a file name
2   Copyright 1990, 1997, 1998, 1999, 2001 Free Software Foundation, Inc.
3
4   This program is free software; you can redistribute it and/or modify
5   it under the terms of the GNU General Public License as published by
6   the Free Software Foundation; either version 2, or (at your option)
7   any later version.
8
9   This program is distributed in the hope that it will be useful,
10   but WITHOUT ANY WARRANTY; without even the implied warranty of
11   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12   GNU General Public License for more details.
13
14   You should have received a copy of the GNU General Public License
15   along with this program; see the file COPYING.
16   If not, write to the Free Software Foundation,
17   59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
18
19/* Written by David MacKenzie <djm@gnu.ai.mit.edu> and Paul Eggert */
20
21#if HAVE_CONFIG_H
22# include <config.h>
23#endif
24
25#ifndef HAVE_DOS_FILE_NAMES
26# define HAVE_DOS_FILE_NAMES 0
27#endif
28#ifndef HAVE_LONG_FILE_NAMES
29# define HAVE_LONG_FILE_NAMES 0
30#endif
31
32#if HAVE_LIMITS_H
33# include <limits.h>
34#endif
35#ifndef _POSIX_NAME_MAX
36# define _POSIX_NAME_MAX 14
37#endif
38
39#include <sys/types.h>
40#if HAVE_STRING_H
41# include <string.h>
42#else
43# include <strings.h>
44#endif
45
46#if HAVE_UNISTD_H
47# include <unistd.h>
48#endif
49
50#include <errno.h>
51#ifndef errno
52extern int errno;
53#endif
54
55#include "backupfile.h"
56#include "dirname.h"
57
58/* Append to FILENAME the extension EXT, unless the result would be too long,
59   in which case just append the character E.  */
60
61void
62addext (char *filename, char const *ext, int e)
63{
64  char *s = base_name (filename);
65  size_t slen = base_len (s);
66  size_t extlen = strlen (ext);
67  size_t slen_max = HAVE_LONG_FILE_NAMES ? 255 : _POSIX_NAME_MAX;
68
69#if HAVE_PATHCONF && defined _PC_NAME_MAX
70  if (_POSIX_NAME_MAX < slen + extlen || HAVE_DOS_FILE_NAMES)
71    {
72      /* The new base name is long enough to require a pathconf check.  */
73      long name_max;
74      errno = 0;
75      if (s == filename)
76	name_max = pathconf (".", _PC_NAME_MAX);
77      else
78	{
79	  char c = *s;
80	  if (! ISSLASH (c))
81	    *s = 0;
82	  name_max = pathconf (filename, _PC_NAME_MAX);
83	  *s = c;
84	}
85      if (0 <= name_max || errno == 0)
86	slen_max = name_max == (size_t) name_max ? name_max : -1;
87    }
88#endif
89
90  if (HAVE_DOS_FILE_NAMES && slen_max <= 12)
91    {
92      /* Live within DOS's 8.3 limit.  */
93      char *dot = strchr (s, '.');
94      if (dot)
95	{
96	  slen -= dot + 1 - s;
97	  s = dot + 1;
98	  slen_max = 3;
99	}
100      else
101	slen_max = 8;
102      extlen = 9; /* Don't use EXT.  */
103    }
104
105  if (slen + extlen <= slen_max)
106    strcpy (s + slen, ext);
107  else
108    {
109      if (slen_max <= slen)
110	slen = slen_max - 1;
111      s[slen] = e;
112      s[slen + 1] = 0;
113    }
114}
115