xref: /netbsd-src/lib/libc/string/memmem.3 (revision 0e03e9aa32bfe10a387a6b8519ad3ec2bc3017c5)
1.\"	$NetBSD: memmem.3,v 1.4 2024/11/01 16:36:58 nia Exp $
2.\"
3.\" Copyright (c) 2005 The NetBSD Foundation, Inc.
4.\" All rights reserved.
5.\"
6.\" This code is derived from software contributed to The NetBSD Foundation
7.\" by Perry E. Metzger of Metzger, Dowdeswell & Co. LLC.
8.\"
9.\" Redistribution and use in source and binary forms, with or without
10.\" modification, are permitted provided that the following conditions
11.\" are met:
12.\" 1. Redistributions of source code must retain the above copyright
13.\"    notice, this list of conditions and the following disclaimer.
14.\" 2. Redistributions in binary form must reproduce the above copyright
15.\"    notice, this list of conditions and the following disclaimer in the
16.\"    documentation and/or other materials provided with the distribution.
17.\"
18.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
19.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
20.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
21.\" PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
22.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
23.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
24.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
25.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
26.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
27.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
28.\" POSSIBILITY OF SUCH DAMAGE.
29.\"
30.Dd November 1, 2024
31.Dt MEMMEM 3
32.Os
33.Sh NAME
34.Nm memmem
35.Nd locate substring in byte string
36.Sh LIBRARY
37.Lb libc
38.Sh SYNOPSIS
39.In string.h
40.Ft void *
41.Fn memmem "const void *block" "size_t blen" "const void *pat" "size_t plen"
42.Sh DESCRIPTION
43The
44.Fn memmem
45function locates the first occurrence of the binary string
46.Fa pat
47of size
48.Fa plen
49bytes in the byte string
50.Fa block
51of size
52.Fa blen
53bytes.
54.Sh RETURN VALUES
55The
56.Fn memmem
57function returns a pointer to the substring located, or
58.Dv NULL
59if no such substring exists within
60.Fa block .
61.Pp
62If
63.Fa plen
64is zero,
65.Fa block
66is returned, i.e. a zero length
67.Fa pat
68is deemed to match the start of the string, as with
69.Xr strstr 3 .
70.Sh SEE ALSO
71.Xr bm 3 ,
72.Xr memchr 3 ,
73.Xr strchr 3 ,
74.Xr strstr 3
75.Sh STANDARDS
76The
77.Nm
78function conforms to
79.St -p1003.1-2024 .
80.Sh HISTORY
81.Fn memmem
82first appeared in the Free Software Foundation's glibc library.
83