memmem started as a GNU extension but is now widely available. Reviewed by: mhorne (slightly earlier version) Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D39337
97 lines
2.8 KiB
Groff
97 lines
2.8 KiB
Groff
.\" Copyright (c) 2005 Pascal Gloor <pascal.gloor@spale.com>
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. The name of the author may not be used to endorse or promote
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.\" products derived from this software without specific prior written
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.\" permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd March 30, 2023
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.Dt MEMMEM 3
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.Os
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.Sh NAME
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.Nm memmem
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.Nd "locate a byte substring in a byte string"
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In string.h
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.Ft "void *"
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.Fo memmem
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.Fa "const void *big" "size_t big_len"
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.Fa "const void *little" "size_t little_len"
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.Fc
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.Sh DESCRIPTION
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The
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.Fn memmem
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function
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locates the first occurrence of the byte string
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.Fa little
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in the byte string
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.Fa big .
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.Sh RETURN VALUES
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If
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.Fa little_len
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is zero
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.Fa big
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is returned (that is, an empty little is deemed to match at the beginning of
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big);
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if
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.Fa little
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occurs nowhere in
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.Fa big ,
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.Dv NULL
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is returned;
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otherwise a pointer to the first character of the first occurrence of
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.Fa little
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is returned.
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.Sh SEE ALSO
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.Xr memchr 3 ,
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.Xr strchr 3 ,
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.Xr strstr 3
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.Sh CONFORMING TO
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.Fn memmem
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started as a GNU extension but is now available in at least
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the GNU, musl, bionic, OpenBSD, NetBSD, macOS, and Illumos C runtime libraries.
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.Sh HISTORY
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The
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.Fn memmem
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function first appeared in
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.Fx 6.0 .
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It was replaced with an optimized O(n) implementation from the musl libc
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project in
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.Fx 12.0 .
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.An Pascal Gloor Aq Mt pascal.gloor@spale.com
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provided this man page along with the previous implementation.
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.Sh BUGS
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This function was broken in Linux libc up to and including version 5.0.9
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and in GNU libc prior to version 2.1.
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Prior to
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.Fx 11.0
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.Nm
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returned
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.Dv NULL
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when
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.Fa little_len
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equals 0.
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