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/* path-concat.c -- concatenate two arbitrary pathnames
Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004 Free
Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software Foundation,
Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
/* Written by Jim Meyering. */
#if HAVE_CONFIG_H
# include <config.h>
#endif
/* Specification. */
#include "path-concat.h"
#include <string.h>
#include "dirname.h"
#include "xalloc.h"
#if ! HAVE_MEMPCPY && ! defined mempcpy
# define mempcpy(D, S, N) ((void *) ((char *) memcpy (D, S, N) + (N)))
#endif
/* Return the longest suffix of F that is a relative file name.
If it has no such suffix, return the empty string. */
static char const *
longest_relative_suffix (char const *f)
{
for (f += FILE_SYSTEM_PREFIX_LEN (f); ISSLASH (*f); f++)
continue;
return f;
}
/* Concatenate two pathname components, DIR and ABASE, in
newly-allocated storage and return the result.
The resulting file name F is such that the commands "ls F" and "(cd
DIR; ls BASE)" refer to the same file, where BASE is ABASE with any
file system prefixes and leading separators removed.
Arrange for a directory separator if necessary between DIR and BASE
in the result, removing any redundant separators.
In any case, if BASE_IN_RESULT is non-NULL, set
*BASE_IN_RESULT to point to the copy of BASE in the returned
concatenation.
Report an error if memory is exhausted. */
char *
path_concat (char const *dir, char const *abase, char **base_in_result)
{
char const *dirbase = base_name (dir);
size_t dirbaselen = base_len (dirbase);
size_t dirlen = dirbase - dir + dirbaselen;
size_t needs_separator = (dirbaselen && ! ISSLASH (dirbase[dirbaselen - 1]));
char const *base = longest_relative_suffix (abase);
size_t baselen = strlen (base);
char *p_concat = xmalloc (dirlen + needs_separator + baselen + 1);
char *p;
p = mempcpy (p_concat, dir, dirlen);
*p = DIRECTORY_SEPARATOR;
p += needs_separator;
if (base_in_result)
*base_in_result = p;
p = mempcpy (p, base, baselen);
*p = '\0';
return p_concat;
}
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