xref: /freebsd/lib/libc/gen/dirname.3 (revision 792bbaba989533a1fc93823df1720c8c4aaf0442)
1.\" $OpenBSD: dirname.3,v 1.17 2007/05/31 19:19:28 jmc Exp $
2.\"
3.\" Copyright (c) 1997 Todd C. Miller <Todd.Miller@courtesan.com>
4.\"
5.\" Permission to use, copy, modify, and distribute this software for any
6.\" purpose with or without fee is hereby granted, provided that the above
7.\" copyright notice and this permission notice appear in all copies.
8.\"
9.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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15.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16.\"
17.\" $FreeBSD$
18.\"
19.Dd September 5, 2016
20.Dt DIRNAME 3
21.Os
22.Sh NAME
23.Nm dirname
24.Nd extract the directory part of a pathname
25.Sh SYNOPSIS
26.In libgen.h
27.Ft char *
28.Fn dirname "char *path"
29.Sh DESCRIPTION
30The
31.Fn dirname
32function is the converse of
33.Xr basename 3 ;
34it returns a pointer to the parent directory of the pathname pointed to by
35.Fa path .
36Any trailing
37.Sq \&/
38characters are not counted as part of the directory
39name.
40.Sh RETURN VALUES
41If
42.Fa path
43is a null pointer, the empty string, or contains no
44.Sq \&/
45characters,
46.Fn dirname
47returns a pointer to the string
48.Qq \&. ,
49signifying the current directory.
50Otherwise,
51it returns a pointer to the parent directory of
52.Fa path .
53.Sh IMPLEMENTATION NOTES
54This implementation of
55.Fn dirname
56uses the buffer provided by the caller to store the resulting parent
57directory.
58Other vendor implementations may return a pointer to internal storage
59space instead.
60The advantage of the former approach is that it ensures thread-safety,
61while also placing no upper limit on the supported length of the
62pathname.
63.Sh SEE ALSO
64.Xr basename 1 ,
65.Xr dirname 1 ,
66.Xr basename 3
67.Sh STANDARDS
68The
69.Fn dirname
70function conforms to
71.St -xpg4.2 .
72.Sh HISTORY
73The
74.Fn dirname
75function first appeared in
76.Ox 2.2
77and
78.Fx 4.2 .
79.Pp
80In
81.Fx 12.0 ,
82this function was reimplemented to store its result in the provided
83input buffer.
84.Sh AUTHORS
85.An Nuxi, the Netherlands
86