89 lines
2.8 KiB
C
89 lines
2.8 KiB
C
/* Concatenate two arbitrary file names.
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Copyright (C) 1996-2007, 2009-2016 Free Software Foundation, Inc.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program 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 General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://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 "dirname.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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/* Return the longest suffix of F that is a relative file name.
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If it has no such suffix, return the empty string. */
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static char const * _GL_ATTRIBUTE_PURE
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longest_relative_suffix (char const *f)
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{
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for (f += FILE_SYSTEM_PREFIX_LEN (f); ISSLASH (*f); f++)
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continue;
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return f;
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}
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/* Concatenate two file name components, DIR and ABASE, 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, where BASE is ABASE with any
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file system prefixes and leading separators removed.
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Arrange for a directory separator if necessary between DIR and BASE
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in the result, removing any redundant separators.
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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 ABASE in the returned
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concatenation. However, if ABASE begins with more than one slash,
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set *BASE_IN_RESULT to point to the sole corresponding slash that
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is copied into the result buffer.
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Return NULL if malloc fails. */
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char *
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mfile_name_concat (char const *dir, char const *abase, 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 needs_separator = (dirbaselen && ! ISSLASH (dirbase[dirbaselen - 1]));
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char const *base = longest_relative_suffix (abase);
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size_t baselen = strlen (base);
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char *p_concat = malloc (dirlen + needs_separator + baselen + 1);
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char *p;
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if (p_concat == NULL)
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return NULL;
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p = mempcpy (p_concat, dir, dirlen);
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*p = DIRECTORY_SEPARATOR;
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p += needs_separator;
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if (base_in_result)
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*base_in_result = p - IS_ABSOLUTE_FILE_NAME (abase);
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p = mempcpy (p, base, baselen);
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*p = '\0';
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return p_concat;
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}
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