lib/addext.c

   1 /* addext.c -- add an extension to a file name
   2
   3    Copyright (C) 1990, 1997, 1998, 1999, 2001, 2003 Free Software
   4    Foundation, Inc.
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 2, or (at your option)
   9    any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; see the file COPYING.
  18    If not, write to the Free Software Foundation,
  19    59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  20
  21 /* Written by David MacKenzie <djm@gnu.ai.mit.edu> and Paul Eggert */
  22
  23 #if HAVE_CONFIG_H
  24 # include <config.h>
  25 #endif
  26
  27 #ifndef HAVE_DOS_FILE_NAMES
  28 # define HAVE_DOS_FILE_NAMES 0
  29 #endif
  30 #ifndef HAVE_LONG_FILE_NAMES
  31 # define HAVE_LONG_FILE_NAMES 0
  32 #endif
  33
  34 #include <limits.h>
  35 #ifndef _POSIX_NAME_MAX
  36 # define _POSIX_NAME_MAX 14
  37 #endif
  38
  39 #include <stddef.h>
  40 #include <string.h>
  41
  42 #if HAVE_UNISTD_H
  43 # include <unistd.h>
  44 #endif
  45
  46 #include <errno.h>
  47 #ifndef errno
  48 extern int errno;
  49 #endif
  50
  51 #include "backupfile.h"
  52 #include "dirname.h"
  53
  54 /* Append to FILENAME the extension EXT, unless the result would be too long,
  55    in which case just append the character E.  */
  56
  57 void
  58 addext (char *filename, char const *ext, int e)
  59 {
  60   char *s = base_name (filename);
  61   size_t slen = base_len (s);
  62   size_t extlen = strlen (ext);
  63   size_t slen_max = HAVE_LONG_FILE_NAMES ? 255 : _POSIX_NAME_MAX;
  64
  65 #if HAVE_PATHCONF && defined _PC_NAME_MAX
  66   if (_POSIX_NAME_MAX < slen + extlen || HAVE_DOS_FILE_NAMES)
  67     {
  68       /* The new base name is long enough to require a pathconf check.  */
  69       long name_max;
  70       errno = 0;
  71       if (s == filename)
  72         name_max = pathconf (".", _PC_NAME_MAX);
  73       else
  74         {
  75           char c = *s;
  76           if (! ISSLASH (c))
  77             *s = 0;
  78           name_max = pathconf (filename, _PC_NAME_MAX);
  79           *s = c;
  80         }
  81       if (0 <= name_max || errno == 0)
  82         {
  83           long size = slen_max = name_max;
  84           if (name_max != size)
  85             slen_max = -1;
  86         }
  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 }