lib/path-concat.c

   1 /* path-concat.c -- concatenate two arbitrary pathnames
   2    Copyright (C) 1996, 1997, 1998 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; if not, write to the Free Software Foundation,
  16    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  17
  18 /* Written by Jim Meyering.  */
  19
  20 #if HAVE_CONFIG_H
  21 # include <config.h>
  22 #endif
  23
  24 #ifndef HAVE_MEMPCPY
  25 # define mempcpy(D, S, N) ((void *) ((char *) memcpy (D, S, N) + (N)))
  26 #endif
  27
  28 #include <stdio.h>
  29 #if HAVE_STRING_H
  30 # include <string.h>
  31 #endif
  32 #include <sys/types.h>
  33
  34 char *malloc ();
  35
  36 /* Concatenate two pathname components, DIR and BASE, in newly-allocated
  37    storage and return the result.  Return 0 if out of memory.  Add a slash
  38    between DIR and BASE in the result if neither would contribute one.
  39    If each would contribute at least one, elide one from the end of DIR.
  40    Otherwise, simply concatenate DIR and BASE.  In any case, if
  41    BASE_IN_RESULT is non-NULL, set *BASE_IN_RESULT to point to the copy of
  42    BASE in the returned concatenation.  */
  43
  44 char *
  45 path_concat (dir, base, base_in_result)
  46      const char *dir;
  47      const char *base;
  48      char **base_in_result;
  49 {
  50   char *p;
  51   char *p_concat;
  52   size_t base_len = strlen (base);
  53   size_t dir_len = strlen (dir);
  54
  55   p_concat = malloc (dir_len + base_len + 2);
  56   if (!p_concat)
  57     return 0;
  58
  59   p = mempcpy (p_concat, dir, dir_len);
  60
  61   if (*(p - 1) == '/' && *base == '/')
  62     --p;
  63   else if (*(p - 1) != '/' && *base != '/')
  64     *p++ = '/';
  65
  66   if (base_in_result)
  67     *base_in_result = p;
  68
  69   memcpy (p, base, base_len + 1);
  70
  71   return p_concat;
  72 }