1  /* addext.c -- add an extension to a file name
       2     Copyright (C) 1990, 1997-1999, 2001-2003, 2005-2006, 2020 Free Software
       3     Foundation, Inc.
       4  
       5     This program is free software: you can redistribute it and/or modify
       6     it under the terms of the GNU General Public License as published by
       7     the Free Software Foundation; either version 3 of the License, or
       8     (at your option) any later version.
       9  
      10     This program is distributed in the hope that it will be useful,
      11     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      13     GNU General Public License for more details.
      14  
      15     You should have received a copy of the GNU General Public License
      16     along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
      17  
      18  /* Written by David MacKenzie <djm@gnu.ai.mit.edu> and Paul Eggert */
      19  
      20  #include <config.h>
      21  
      22  #ifndef HAVE_DOS_FILE_NAMES
      23  # define HAVE_DOS_FILE_NAMES 0
      24  #endif
      25  #ifndef HAVE_LONG_FILE_NAMES
      26  # define HAVE_LONG_FILE_NAMES 0
      27  #endif
      28  
      29  #include "backupfile.h"
      30  
      31  #include <limits.h>
      32  #ifndef _POSIX_NAME_MAX
      33  # define _POSIX_NAME_MAX 14
      34  #endif
      35  
      36  #include <sys/types.h>
      37  #if HAVE_STRING_H
      38  # include <string.h>
      39  #else
      40  # include <strings.h>
      41  #endif
      42  
      43  #include <unistd.h>
      44  
      45  #include "basename-lgpl.h"
      46  
      47  /* Append to FILENAME the extension EXT, unless the result would be too long,
      48     in which case just append the character E.  */
      49  
      50  void
      51  addext (char *filename, char const *ext, char e)
      52  {
      53    char *s = last_component (filename);
      54    size_t slen = strlen (s), extlen = strlen (ext);
      55    long slen_max = -1;
      56  
      57  #if HAVE_PATHCONF && defined _PC_NAME_MAX
      58    if (slen + extlen <= _POSIX_NAME_MAX && ! HAVE_DOS_FILE_NAMES)
      59      /* The file name is so short there's no need to call pathconf.  */
      60      slen_max = _POSIX_NAME_MAX;
      61    else if (s == filename)
      62      slen_max = pathconf (".", _PC_NAME_MAX);
      63    else
      64      {
      65        char c = *s;
      66        *s = 0;
      67        slen_max = pathconf (filename, _PC_NAME_MAX);
      68        *s = c;
      69      }
      70  #endif
      71    if (slen_max < 0)
      72      slen_max = HAVE_LONG_FILE_NAMES ? 255 : 14;
      73  
      74    if (HAVE_DOS_FILE_NAMES && slen_max <= 12)
      75      {
      76        /* Live within DOS's 8.3 limit.  */
      77        char *dot = strchr (s, '.');
      78        if (dot)
      79          {
      80            slen -= dot + 1 - s;
      81            s = dot + 1;
      82            slen_max = 3;
      83          }
      84        else
      85          slen_max = 8;
      86        extlen = 9; /* Don't use EXT.  */
      87      }
      88  
      89    if (slen + extlen <= slen_max)
      90      strcpy (s + slen, ext);
      91    else
      92      {
      93        if (slen_max <= slen)
      94          slen = slen_max - 1;
      95        s[slen] = e;
      96        s[slen + 1] = 0;
      97      }
      98  }