1/***********************************************************************
2*                                                                      *
3*               This software is part of the ast package               *
4*          Copyright (c) 1985-2011 AT&T Intellectual Property          *
5*                      and is licensed under the                       *
6*                  Common Public License, Version 1.0                  *
7*                    by AT&T Intellectual Property                     *
8*                                                                      *
9*                A copy of the License is available at                 *
10*            http://www.opensource.org/licenses/cpl1.0.txt             *
11*         (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9)         *
12*                                                                      *
13*              Information and Software Systems Research               *
14*                            AT&T Research                             *
15*                           Florham Park NJ                            *
16*                                                                      *
17*                 Glenn Fowler <gsf@research.att.com>                  *
18*                  David Korn <dgk@research.att.com>                   *
19*                   Phong Vo <kpv@research.att.com>                    *
20*                                                                      *
21***********************************************************************/
22#include	"sfhdr.h"
23
24/*	Obtain/release exclusive use of a stream.
25**
26**	Written by Kiem-Phong Vo.
27*/
28
29/* the main locking/unlocking interface */
30#if __STD_C
31int sfmutex(Sfio_t* f, int type)
32#else
33int sfmutex(f, type)
34Sfio_t*	f;
35int	type;
36#endif
37{
38#if !vt_threaded
39	NOTUSED(f); NOTUSED(type);
40	return 0;
41#else
42
43	SFONCE();
44
45	if(!f)
46		return -1;
47
48	if(!f->mutex)
49	{	if(f->bits&SF_PRIVATE)
50			return 0;
51
52		vtmtxlock(_Sfmutex);
53		f->mutex = vtmtxopen(NIL(Vtmutex_t*), VT_INIT);
54		vtmtxunlock(_Sfmutex);
55		if(!f->mutex)
56			return -1;
57	}
58
59	if(type == SFMTX_LOCK)
60		return vtmtxlock(f->mutex);
61	else if(type == SFMTX_TRYLOCK)
62		return vtmtxtrylock(f->mutex);
63	else if(type == SFMTX_UNLOCK)
64		return vtmtxunlock(f->mutex);
65	else if(type == SFMTX_CLRLOCK)
66		return vtmtxclrlock(f->mutex);
67	else	return -1;
68#endif /*vt_threaded*/
69}
70