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GitHub Repository: att/ast
 Path: blob/master/src/lib/libcs/cspeek.c
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/***********************************************************************

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*                                                                      *

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*               This software is part of the ast package               *

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*          Copyright (c) 1990-2011 AT&T Intellectual Property          *

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*                      and is licensed under the                       *

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*                 Eclipse Public License, Version 1.0                  *

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*                    by AT&T Intellectual Property                     *

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*                                                                      *

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*                A copy of the License is available at                 *

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*          http://www.eclipse.org/org/documents/epl-v10.html           *

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*         (with md5 checksum b35adb5213ca9657e911e9befb180842)         *

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*                                                                      *

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*              Information and Software Systems Research               *

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*                            AT&T Research                             *

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*                           Florham Park NJ                            *

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*                                                                      *

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*                 Glenn Fowler <[email protected]>                  *

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*                                                                      *

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***********************************************************************/

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#pragma prototyped

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#include "cslib.h"

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#if _socket_peek && !CS_LIB_SOCKET

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#include <sys/socket.h>

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#endif

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#if _stream_peek && !CS_LIB_STREAM

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#include <stropts.h>

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#endif

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/*

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 * peek up to siz chars from fd into buf

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 * -1 returned if fd not peekable

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 *

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 * NOTE: cspeek() caches the peek state of fd

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 *	 call cspeek(-1,...) to flush the cache

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 */

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ssize_t

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cspeek(register Cs_t* state, int fd, void* buf, size_t siz)

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{

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	register int	n;

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#if _stream_peek

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	struct strpeek	pk;

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#endif

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	if (fd == -1)

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	{

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#if _stream_peek

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		state->nostream = -1;

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#endif

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#if _socket_peek

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		state->nosocket = -1;

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#endif

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		return -1;

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	}

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#if _stream_peek

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	if (fd != state->nostream)

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	{

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		pk.flags = 0;

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		pk.ctlbuf.maxlen = -1;

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		pk.ctlbuf.len = 0;

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		pk.ctlbuf.buf = 0;

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		pk.databuf.maxlen = siz;

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		pk.databuf.buf = (char*)buf;

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		pk.databuf.len = 0;

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		if ((n = ioctl(fd, I_PEEK, &pk)) >= 0)

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		{

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			state->nostream = -1;

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			if (n > 0) n = pk.databuf.len;

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			return n;

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		}

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		messagef((state->id, NiL, -1, "peek: %d: ioctl I_PEEK error", fd));

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		state->nostream = fd;

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	}

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#endif

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#if _socket_peek

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	if (fd != state->nosocket)

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	{

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		if ((n = recv(fd, (char*)buf, siz, MSG_PEEK)) >= 0)

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		{

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			state->nosocket = -1;

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			return n;

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		}

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		messagef((state->id, NiL, -1, "peek: %d: recv MSG_PEEK error", fd));

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		state->nosocket = fd;

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	}

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#endif

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	messagef((state->id, NiL, -1, "peek: %d: no peek", fd));

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	return -1;

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}

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ssize_t

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_cs_peek(int fd, void* buf, size_t siz)

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{

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	return cspeek(&cs, fd, buf, siz);

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}

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