lib/addext.c

   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
  52 extern 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
  61 void
  62 addext (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 }