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88 lines
2.7 KiB
C
88 lines
2.7 KiB
C
/* path-concat.c -- concatenate two arbitrary pathnames
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Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004 Free
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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 2, or (at your option)
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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, write to the Free Software Foundation,
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Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
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/* Written by Jim Meyering. */
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#if HAVE_CONFIG_H
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# include <config.h>
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#endif
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/* Specification. */
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#include "path-concat.h"
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#include <string.h>
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#include "dirname.h"
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#include "xalloc.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 *
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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 pathname 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 BASE in the returned
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concatenation.
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Report an error if memory is exhausted. */
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char *
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path_concat (char const *dir, char const *abase, char **base_in_result)
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{
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char const *dirbase = base_name (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 = xmalloc (dirlen + needs_separator + baselen + 1);
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char *p;
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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;
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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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