1 /* Concatenate two arbitrary file names.
3 Copyright (C) 1996-2007 Free Software Foundation, Inc.
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.
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.
15 You should have received a copy of the GNU General Public License
16 along with this program. If not, see <http://www.gnu.org/licenses/>. */
18 /* Written by Jim Meyering. */
23 #include "filenamecat.h"
31 #if ! HAVE_MEMPCPY && ! defined mempcpy
32 # define mempcpy(D, S, N) ((void *) ((char *) memcpy (D, S, N) + (N)))
35 /* Return the longest suffix of F that is a relative file name.
36 If it has no such suffix, return the empty string. */
39 longest_relative_suffix (char const *f)
41 for (f += FILE_SYSTEM_PREFIX_LEN (f); ISSLASH (*f); f++)
46 /* Concatenate two file name components, DIR and ABASE, in
47 newly-allocated storage and return the result.
48 The resulting file name F is such that the commands "ls F" and "(cd
49 DIR; ls BASE)" refer to the same file, where BASE is ABASE with any
50 file system prefixes and leading separators removed.
51 Arrange for a directory separator if necessary between DIR and BASE
52 in the result, removing any redundant separators.
53 In any case, if BASE_IN_RESULT is non-NULL, set
54 *BASE_IN_RESULT to point to the copy of ABASE in the returned
55 concatenation. However, if ABASE begins with more than one slash,
56 set *BASE_IN_RESULT to point to the sole corresponding slash that
57 is copied into the result buffer.
59 Return NULL if malloc fails. */
62 mfile_name_concat (char const *dir, char const *abase, char **base_in_result)
64 char const *dirbase = last_component (dir);
65 size_t dirbaselen = base_len (dirbase);
66 size_t dirlen = dirbase - dir + dirbaselen;
67 size_t needs_separator = (dirbaselen && ! ISSLASH (dirbase[dirbaselen - 1]));
69 char const *base = longest_relative_suffix (abase);
70 size_t baselen = strlen (base);
72 char *p_concat = malloc (dirlen + needs_separator + baselen + 1);
78 p = mempcpy (p_concat, dir, dirlen);
79 *p = DIRECTORY_SEPARATOR;
83 *base_in_result = p - IS_ABSOLUTE_FILE_NAME (abase);
85 p = mempcpy (p, base, baselen);
91 /* Just like mfile_name_concat, above, except, rather than
92 returning NULL upon malloc failure, here, we report the
93 "memory exhausted" condition and exit. */
96 file_name_concat (char const *dir, char const *abase, char **base_in_result)
98 char *p = mfile_name_concat (dir, abase, base_in_result);