/***********************************************************************
* *
* This software is part of the ast package *
* Copyright (c) 1985-2011 AT&T Intellectual Property *
* and is licensed under the *
* Eclipse Public License, Version 1.0 *
* by AT&T Intellectual Property *
* *
* A copy of the License is available at *
* http://www.eclipse.org/org/documents/epl-v10.html *
* (with md5 checksum b35adb5213ca9657e911e9befb180842) *
* *
* Information and Software Systems Research *
* AT&T Research *
* Florham Park NJ *
* *
* Glenn Fowler <gsf@research.att.com> *
* David Korn <dgk@research.att.com> *
* Phong Vo <kpv@research.att.com> *
* *
***********************************************************************/
#include "sfhdr.h"
/* Obtain/release exclusive use of a stream.
**
** Written by Kiem-Phong Vo.
*/
/* the main locking/unlocking interface */
#if __STD_C
int sfmutex(Sfio_t* f, int type)
#else
int sfmutex(f, type)
Sfio_t* f;
int type;
#endif
{
#if !vt_threaded
NOTUSED(f); NOTUSED(type);
return 0;
#else
SFONCE();
if(!f)
return -1;
if(!f->mutex)
{ if(f->bits&SF_PRIVATE)
return 0;
vtmtxlock(_Sfmutex);
f->mutex = vtmtxopen(NIL(Vtmutex_t*), VT_INIT);
vtmtxunlock(_Sfmutex);
if(!f->mutex)
return -1;
}
if(type == SFMTX_LOCK)
return vtmtxlock(f->mutex);
else if(type == SFMTX_TRYLOCK)
return vtmtxtrylock(f->mutex);
else if(type == SFMTX_UNLOCK)
return vtmtxunlock(f->mutex);
else if(type == SFMTX_CLRLOCK)
return vtmtxclrlock(f->mutex);
else return -1;
#endif /*vt_threaded*/
}