1 | /* dirname.c -- return all but the last element in a file name |
2 | |
3 | Copyright (C) 1990, 1998, 2000-2001, 2003-2006, 2009-2019 Free Software |
4 | Foundation, Inc. |
5 | |
6 | This program is free software: you can redistribute it and/or modify |
7 | it under the terms of the GNU General Public License as published by |
8 | the Free Software Foundation; either version 3 of the License, or |
9 | (at your option) any later version. |
10 | |
11 | This program is distributed in the hope that it will be useful, |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
14 | GNU General Public License for more details. |
15 | |
16 | You should have received a copy of the GNU General Public License |
17 | along with this program. If not, see <https://www.gnu.org/licenses/>. */ |
18 | |
19 | #include <config.h> |
20 | |
21 | #include "dirname.h" |
22 | |
23 | #include <stdlib.h> |
24 | #include <string.h> |
25 | |
26 | /* Return the length of the prefix of FILE that will be used by |
27 | dir_name. If FILE is in the working directory, this returns zero |
28 | even though 'dir_name (FILE)' will return ".". Works properly even |
29 | if there are trailing slashes (by effectively ignoring them). */ |
30 | |
31 | size_t |
32 | dir_len (char const *file) |
33 | { |
34 | size_t prefix_length = FILE_SYSTEM_PREFIX_LEN (file); |
35 | size_t length; |
36 | |
37 | /* Advance prefix_length beyond important leading slashes. */ |
38 | prefix_length += (prefix_length != 0 |
39 | ? (FILE_SYSTEM_DRIVE_PREFIX_CAN_BE_RELATIVE |
40 | && ISSLASH (file[prefix_length])) |
41 | : (ISSLASH (file[0]) |
42 | ? ((DOUBLE_SLASH_IS_DISTINCT_ROOT |
43 | && ISSLASH (file[1]) && ! ISSLASH (file[2]) |
44 | ? 2 : 1)) |
45 | : 0)); |
46 | |
47 | /* Strip the basename and any redundant slashes before it. */ |
48 | for (length = last_component (file) - file; |
49 | prefix_length < length; length--) |
50 | if (! ISSLASH (file[length - 1])) |
51 | break; |
52 | return length; |
53 | } |
54 | |
55 | |
56 | /* In general, we can't use the builtin 'dirname' function if available, |
57 | since it has different meanings in different environments. |
58 | In some environments the builtin 'dirname' modifies its argument. |
59 | |
60 | Return the leading directories part of FILE, allocated with malloc. |
61 | Works properly even if there are trailing slashes (by effectively |
62 | ignoring them). Return NULL on failure. |
63 | |
64 | If lstat (FILE) would succeed, then { chdir (dir_name (FILE)); |
65 | lstat (base_name (FILE)); } will access the same file. Likewise, |
66 | if the sequence { chdir (dir_name (FILE)); |
67 | rename (base_name (FILE), "foo"); } succeeds, you have renamed FILE |
68 | to "foo" in the same directory FILE was in. */ |
69 | |
70 | char * |
71 | mdir_name (char const *file) |
72 | { |
73 | size_t length = dir_len (file); |
74 | bool append_dot = (length == 0 |
75 | || (FILE_SYSTEM_DRIVE_PREFIX_CAN_BE_RELATIVE |
76 | && length == FILE_SYSTEM_PREFIX_LEN (file) |
77 | && file[2] != '\0' && ! ISSLASH (file[2]))); |
78 | char *dir = malloc (length + append_dot + 1); |
79 | if (!dir) |
80 | return NULL; |
81 | memcpy (dir, file, length); |
82 | if (append_dot) |
83 | dir[length++] = '.'; |
84 | dir[length] = '\0'; |
85 | return dir; |
86 | } |
87 | |