'\" te
.\" Copyright (c) 2006, Sun Microsystems, Inc. All Rights Reserved.
.\" Copyright 1989 AT&T
.\" The contents of this file are subject to the terms of the Common Development and Distribution License (the "License").  You may not use this file except in compliance with the License.
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.TH unlinkb 9F "16 Jan 2006" "SunOS 5.11" "Kernel Functions for Drivers"
.SH NAME
unlinkb \- remove a message block from the head of a message
.SH SYNOPSIS
.LP
.nf
#include <sys/stream.h>



\fBmblk_t *\fR\fBunlinkb\fR(\fBmblk_t *\fR\fImp\fR);
.fi

.SH INTERFACE LEVEL
.sp
.LP
Architecture independent level 1 (DDI/DKI).
.SH PARAMETERS
.sp
.ne 2
.mk
.na
\fB\fImp\fR\fR
.ad
.RS 6n
.rt  
Pointer to the message.
.RE

.SH DESCRIPTION
.sp
.LP
The \fBunlinkb()\fR function removes the first message block from the message
pointed to by \fImp\fR. A new message, minus the removed message block, is
returned.
.SH RETURN VALUES
.sp
.LP
If successful, the \fBunlinkb()\fR function returns a pointer to the message
with the first message block removed. If there is only one message block in the
message, \fINULL\fR is returned.
.SH CONTEXT
.sp
.LP
The \fBunlinkb()\fR function can be called from user, interrupt, or kernel
context.
.SH EXAMPLES
.LP
\fBExample 1 \fR\fBunlinkb()\fR example
.sp
.LP
The routine expects to get passed an \fBM_PROTO T_DATA_IND\fR message. It will
remove and free the  \fBM_PROTO\fR header and return the remaining
\fBM_DATA\fR portion of the message.

.sp
.in +2
.nf
1  mblk_t *
2  makedata(mp)
3      mblk_t *mp;
4  {
5	mblk_t *nmp;
6
7	nmp = unlinkb(mp);
8	freeb(mp);
9	return(nmp);
10 }
.fi
.in -2

.SH SEE ALSO
.sp
.LP
\fBlinkb\fR(9F)
.sp
.LP
\fIWriting Device Drivers\fR
.sp
.LP
\fISTREAMS Programming Guide\fR