1/* dirname - return directory part of PATH.
2 Copyright (C) 1996-2020 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.
5
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
10
11 The GNU C Library 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 GNU
14 Lesser General Public License for more details.
15
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, see
18 <https://www.gnu.org/licenses/>. */
19
20#include <libgen.h>
21#include <string.h>
22
23
24char *
25dirname (char *path)
26{
27 static const char dot[] = ".";
28 char *last_slash;
29
30 /* Find last '/'. */
31 last_slash = path != NULL ? strrchr (path, '/') : NULL;
32
33 if (last_slash != NULL && last_slash != path && last_slash[1] == '\0')
34 {
35 /* Determine whether all remaining characters are slashes. */
36 char *runp;
37
38 for (runp = last_slash; runp != path; --runp)
39 if (runp[-1] != '/')
40 break;
41
42 /* The '/' is the last character, we have to look further. */
43 if (runp != path)
44 last_slash = __memrchr (path, '/', runp - path);
45 }
46
47 if (last_slash != NULL)
48 {
49 /* Determine whether all remaining characters are slashes. */
50 char *runp;
51
52 for (runp = last_slash; runp != path; --runp)
53 if (runp[-1] != '/')
54 break;
55
56 /* Terminate the path. */
57 if (runp == path)
58 {
59 /* The last slash is the first character in the string. We have to
60 return "/". As a special case we have to return "//" if there
61 are exactly two slashes at the beginning of the string. See
62 XBD 4.10 Path Name Resolution for more information. */
63 if (last_slash == path + 1)
64 ++last_slash;
65 else
66 last_slash = path + 1;
67 }
68 else
69 last_slash = runp;
70
71 last_slash[0] = '\0';
72 }
73 else
74 /* This assignment is ill-designed but the XPG specs require to
75 return a string containing "." in any case no directory part is
76 found and so a static and constant string is required. */
77 path = (char *) dot;
78
79 return path;
80}
81