91 lines
2.8 KiB
C
91 lines
2.8 KiB
C
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/* Concatenate two arbitrary file names.
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Copyright (C) 1996-2007, 2009-2023 Free Software Foundation, Inc.
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This file is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation; either version 2.1 of the
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License, or (at your option) any later version.
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This file is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>. */
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/* Written by Jim Meyering. */
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#include <config.h>
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/* Specification. */
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#include "filenamecat.h"
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#include <stdlib.h>
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#include <string.h>
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#include "basename-lgpl.h"
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#include "filename.h"
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#if ! HAVE_MEMPCPY && ! defined mempcpy
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# define mempcpy(D, S, N) ((void *) ((char *) memcpy (D, S, N) + (N)))
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#endif
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/* Concatenate two file name components, DIR and BASE, in
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newly-allocated storage and return the result.
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The resulting file name F is such that the commands "ls F" and "(cd
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DIR; ls ./BASE)" refer to the same file. If necessary, put
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a separator between DIR and BASE in the result. Typically this
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separator is "/", but in rare cases it might be ".".
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In any case, if BASE_IN_RESULT is non-NULL, set
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*BASE_IN_RESULT to point to the copy of BASE at the end of the
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returned concatenation.
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If malloc fails, return NULL with errno set. */
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char *
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mfile_name_concat (char const *dir, char const *base, char **base_in_result)
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{
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char const *dirbase = last_component (dir);
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size_t dirbaselen = base_len (dirbase);
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size_t dirlen = dirbase - dir + dirbaselen;
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size_t baselen = strlen (base);
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char sep = '\0';
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if (dirbaselen)
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{
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/* DIR is not a file system root, so separate with / if needed. */
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if (! ISSLASH (dir[dirlen - 1]) && ! ISSLASH (*base))
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sep = '/';
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}
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else if (ISSLASH (*base))
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{
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/* DIR is a file system root and BASE begins with a slash, so
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separate with ".". For example, if DIR is "/" and BASE is
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"/foo" then return "/./foo", as "//foo" would be wrong on
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some POSIX systems. A fancier algorithm could omit "." in
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some cases but is not worth the trouble. */
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sep = '.';
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}
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char *p_concat = malloc (dirlen + (sep != '\0') + baselen + 1);
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if (p_concat == NULL)
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return NULL;
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{
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char *p;
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p = mempcpy (p_concat, dir, dirlen);
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*p = sep;
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p += sep != '\0';
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if (base_in_result)
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*base_in_result = p;
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p = mempcpy (p, base, baselen);
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*p = '\0';
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}
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return p_concat;
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}
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