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6a29c58e YQ |
1 | /* dirname.c -- return all but the last element in a file name |
2 | ||
5df4cba6 | 3 | Copyright (C) 1990, 1998, 2000-2001, 2003-2006, 2009-2020 Free Software |
6a29c58e YQ |
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 | |
c0c3707f | 17 | along with this program. If not, see <https://www.gnu.org/licenses/>. */ |
6a29c58e YQ |
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 | } |