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/*
* Copyright (c) 2003-2003
* Fraunhofer Institute for Open Communication Systems (FhG Fokus).
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* Author: Hartmut Brandt <harti@freebsd.org>
*
* $Begemot: libunimsg/atm/misc/unimsg_common.c,v 1.2 2003/09/19 12:05:45 hbb Exp $
*/
#include <netnatm/unimsg.h>
/*
* Make sure there is enough space in front of the data for
* len bytes, and update the read pointer.
*/
int
uni_msg_prepend(struct uni_msg *msg, size_t len)
{
size_t need;
if (uni_msg_leading(msg) >= len) {
msg->b_rptr -= len;
return (0);
}
need = len - uni_msg_leading(msg);
if (uni_msg_ensure(msg, need))
return (-1);
memcpy(msg->b_rptr + need, msg->b_rptr, uni_msg_len(msg));
msg->b_rptr += need - len;
msg->b_wptr += need;
return (0);
}
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