87 lines
3.1 KiB
C
87 lines
3.1 KiB
C
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/* dirname.c -- return all but the last element in a file name
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Copyright (C) 1990, 1998, 2000-2001, 2003-2006, 2009-2023 Free Software
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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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#include <config.h>
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#include "dirname.h"
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#include <stdlib.h>
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#include <string.h>
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/* Return the length of the prefix of FILE that will be used by
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dir_name. If FILE is in the working directory, this returns zero
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even though 'dir_name (FILE)' will return ".". Works properly even
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if there are trailing slashes (by effectively ignoring them). */
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size_t
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dir_len (char const *file)
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{
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size_t prefix_length = FILE_SYSTEM_PREFIX_LEN (file);
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size_t length;
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/* Advance prefix_length beyond important leading slashes. */
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prefix_length += (prefix_length != 0
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? (FILE_SYSTEM_DRIVE_PREFIX_CAN_BE_RELATIVE
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&& ISSLASH (file[prefix_length]))
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: (ISSLASH (file[0])
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? ((DOUBLE_SLASH_IS_DISTINCT_ROOT
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&& ISSLASH (file[1]) && ! ISSLASH (file[2])
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? 2 : 1))
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: 0));
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/* Strip the basename and any redundant slashes before it. */
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for (length = last_component (file) - file;
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prefix_length < length; length--)
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if (! ISSLASH (file[length - 1]))
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break;
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return length;
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}
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/* In general, we can't use the builtin 'dirname' function if available,
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since it has different meanings in different environments.
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In some environments the builtin 'dirname' modifies its argument.
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Return the leading directories part of FILE, allocated with malloc.
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Works properly even if there are trailing slashes (by effectively
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ignoring them). Return NULL on failure.
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If lstat (FILE) would succeed, then { chdir (dir_name (FILE));
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lstat (base_name (FILE)); } will access the same file. Likewise,
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if the sequence { chdir (dir_name (FILE));
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rename (base_name (FILE), "foo"); } succeeds, you have renamed FILE
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to "foo" in the same directory FILE was in. */
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char *
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mdir_name (char const *file)
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{
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size_t length = dir_len (file);
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bool append_dot = (length == 0
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|| (FILE_SYSTEM_DRIVE_PREFIX_CAN_BE_RELATIVE
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&& length == FILE_SYSTEM_PREFIX_LEN (file)
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&& file[2] != '\0' && ! ISSLASH (file[2])));
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char *dir = malloc (length + append_dot + 1);
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if (!dir)
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return NULL;
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memcpy (dir, file, length);
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if (append_dot)
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dir[length++] = '.';
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dir[length] = '\0';
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return dir;
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}
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