blob: 008a6407b50fdf4a831d0fbc41d1837dd32066df [file] [log] [blame]
/* Concatenate two arbitrary file names.
Copyright (C) 1996-2007, 2009-2021 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 3 of the License, 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
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, see <>. */
/* Written by Jim Meyering. */
#include <config.h>
/* Specification. */
#include "filenamecat.h"
#include <stdlib.h>
#include <string.h>
#include "basename-lgpl.h"
#include "filename.h"
#if ! HAVE_MEMPCPY && ! defined mempcpy
# define mempcpy(D, S, N) ((void *) ((char *) memcpy (D, S, N) + (N)))
/* Concatenate two file name components, DIR and BASE, 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. If necessary, put
a separator between DIR and BASE in the result. Typically this
separator is "/", but in rare cases it might be ".".
In any case, if BASE_IN_RESULT is non-NULL, set
*BASE_IN_RESULT to point to the copy of BASE at the end of the
returned concatenation.
If malloc fails, return NULL with errno set. */
char *
mfile_name_concat (char const *dir, char const *base, char **base_in_result)
char const *dirbase = last_component (dir);
size_t dirbaselen = base_len (dirbase);
size_t dirlen = dirbase - dir + dirbaselen;
size_t baselen = strlen (base);
char sep = '\0';
if (dirbaselen)
/* DIR is not a file system root, so separate with / if needed. */
if (! ISSLASH (dir[dirlen - 1]) && ! ISSLASH (*base))
sep = '/';
else if (ISSLASH (*base))
/* DIR is a file system root and BASE begins with a slash, so
separate with ".". For example, if DIR is "/" and BASE is
"/foo" then return "/./foo", as "//foo" would be wrong on
some POSIX systems. A fancier algorithm could omit "." in
some cases but is not worth the trouble. */
sep = '.';
char *p_concat = malloc (dirlen + (sep != '\0') + baselen + 1);
if (p_concat == NULL)
return NULL;
char *p;
p = mempcpy (p_concat, dir, dirlen);
*p = sep;
p += sep != '\0';
if (base_in_result)
*base_in_result = p;
p = mempcpy (p, base, baselen);
*p = '\0';
return p_concat;