| 1 | /* dirname.c -- return all but the last element in a file name
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| 2 |
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| 3 | Copyright (C) 1990, 1998, 2000-2001, 2003-2006, 2009-2022 Free Software
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| 4 | Foundation, Inc.
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| 5 |
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| 6 | This file is free software: you can redistribute it and/or modify
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| 7 | it under the terms of the GNU Lesser General Public License as
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| 8 | published by the Free Software Foundation; either version 2.1 of the
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| 9 | License, or (at your option) any later version.
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| 10 |
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| 11 | This file is distributed in the hope that it will be useful,
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| 12 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 14 | GNU Lesser General Public License for more details.
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| 15 |
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| 16 | You should have received a copy of the GNU Lesser General Public License
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| 17 | along with this program. If not, see <https://www.gnu.org/licenses/>. */
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| 18 |
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| 19 | #include <config.h>
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| 20 |
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| 21 | #include "dirname.h"
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| 22 |
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| 23 | #include <stdlib.h>
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| 24 | #include <string.h>
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| 25 |
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| 26 | /* Return the length of the prefix of FILE that will be used by
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| 27 | dir_name. If FILE is in the working directory, this returns zero
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| 28 | even though 'dir_name (FILE)' will return ".". Works properly even
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| 29 | if there are trailing slashes (by effectively ignoring them). */
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| 30 |
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| 31 | size_t
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| 32 | dir_len (char const *file)
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| 33 | {
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| 34 | size_t prefix_length = FILE_SYSTEM_PREFIX_LEN (file);
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| 35 | size_t length;
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| 36 |
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| 37 | /* Advance prefix_length beyond important leading slashes. */
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| 38 | prefix_length += (prefix_length != 0
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| 39 | ? (FILE_SYSTEM_DRIVE_PREFIX_CAN_BE_RELATIVE
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| 40 | && ISSLASH (file[prefix_length]))
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| 41 | : (ISSLASH (file[0])
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| 42 | ? ((DOUBLE_SLASH_IS_DISTINCT_ROOT
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| 43 | && ISSLASH (file[1]) && ! ISSLASH (file[2])
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| 44 | ? 2 : 1))
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| 45 | : 0));
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| 46 |
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| 47 | /* Strip the basename and any redundant slashes before it. */
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| 48 | for (length = last_component (file) - file;
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| 49 | prefix_length < length; length--)
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| 50 | if (! ISSLASH (file[length - 1]))
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| 51 | break;
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| 52 | return length;
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| 53 | }
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| 54 |
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| 55 |
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| 56 | /* In general, we can't use the builtin 'dirname' function if available,
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| 57 | since it has different meanings in different environments.
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| 58 | In some environments the builtin 'dirname' modifies its argument.
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| 59 |
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| 60 | Return the leading directories part of FILE, allocated with malloc.
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| 61 | Works properly even if there are trailing slashes (by effectively
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| 62 | ignoring them). Return NULL on failure.
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| 63 |
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| 64 | If lstat (FILE) would succeed, then { chdir (dir_name (FILE));
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| 65 | lstat (base_name (FILE)); } will access the same file. Likewise,
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| 66 | if the sequence { chdir (dir_name (FILE));
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| 67 | rename (base_name (FILE), "foo"); } succeeds, you have renamed FILE
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| 68 | to "foo" in the same directory FILE was in. */
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| 69 |
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| 70 | char *
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| 71 | mdir_name (char const *file)
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| 72 | {
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| 73 | size_t length = dir_len (file);
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| 74 | bool append_dot = (length == 0
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| 75 | || (FILE_SYSTEM_DRIVE_PREFIX_CAN_BE_RELATIVE
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| 76 | && length == FILE_SYSTEM_PREFIX_LEN (file)
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| 77 | && file[2] != '\0' && ! ISSLASH (file[2])));
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| 78 | char *dir = malloc (length + append_dot + 1);
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| 79 | if (!dir)
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| 80 | return NULL;
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| 81 | memcpy (dir, file, length);
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| 82 | if (append_dot)
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| 83 | dir[length++] = '.';
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| 84 | dir[length] = '\0';
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| 85 | return dir;
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| 86 | }
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