1/* dirname - return directory part of PATH.
2 Copyright (C) 1996-2023 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19#include <libgen.h>
20#include <string.h>
21
22
23char *
24dirname (char *path)
25{
26 static const char dot[] = ".";
27 char *last_slash;
28
29 /* Find last '/'. */
30 last_slash = path != NULL ? strrchr (path, '/') : NULL;
31
32 if (last_slash != NULL && last_slash != path && last_slash[1] == '\0')
33 {
34 /* Determine whether all remaining characters are slashes. */
35 char *runp;
36
37 for (runp = last_slash; runp != path; --runp)
38 if (runp[-1] != '/')
39 break;
40
41 /* The '/' is the last character, we have to look further. */
42 if (runp != path)
43 last_slash = __memrchr (path, '/', runp - path);
44 }
45
46 if (last_slash != NULL)
47 {
48 /* Determine whether all remaining characters are slashes. */
49 char *runp;
50
51 for (runp = last_slash; runp != path; --runp)
52 if (runp[-1] != '/')
53 break;
54
55 /* Terminate the path. */
56 if (runp == path)
57 {
58 /* The last slash is the first character in the string. We have to
59 return "/". As a special case we have to return "//" if there
60 are exactly two slashes at the beginning of the string. See
61 XBD 4.10 Path Name Resolution for more information. */
62 if (last_slash == path + 1)
63 ++last_slash;
64 else
65 last_slash = path + 1;
66 }
67 else
68 last_slash = runp;
69
70 last_slash[0] = '\0';
71 }
72 else
73 /* This assignment is ill-designed but the XPG specs require to
74 return a string containing "." in any case no directory part is
75 found and so a static and constant string is required. */
76 path = (char *) dot;
77
78 return path;
79}
80