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att
GitHub Repository: att/ast
 Path: blob/master/src/lib/libast/sfio/sfmutex.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) 1985-2011 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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*                  David Korn <[email protected]>                   *

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*                   Phong Vo <[email protected]>                    *

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*                                                                      *

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

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#include	"sfhdr.h"

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/*	Obtain/release exclusive use of a stream.

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**

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**	Written by Kiem-Phong Vo.

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*/

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/* the main locking/unlocking interface */

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#if __STD_C

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int sfmutex(Sfio_t* f, int type)

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#else

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int sfmutex(f, type)

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Sfio_t*	f;

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int	type;

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#endif

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{

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#if !vt_threaded

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	NOTUSED(f); NOTUSED(type);

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	return 0;

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#else

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	SFONCE();

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	if(!f)

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		return -1;

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	if(!f->mutex)

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	{	if(f->bits&SF_PRIVATE)

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			return 0;

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		vtmtxlock(_Sfmutex);

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		f->mutex = vtmtxopen(NIL(Vtmutex_t*), VT_INIT);

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		vtmtxunlock(_Sfmutex);

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		if(!f->mutex)

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			return -1;

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	}

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	if(type == SFMTX_LOCK)

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		return vtmtxlock(f->mutex);

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	else if(type == SFMTX_TRYLOCK)

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		return vtmtxtrylock(f->mutex);

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	else if(type == SFMTX_UNLOCK)

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		return vtmtxunlock(f->mutex);

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	else if(type == SFMTX_CLRLOCK)

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		return vtmtxclrlock(f->mutex);

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	else	return -1;

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#endif /*vt_threaded*/

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}

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