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 *                 Eclipse Public License, Version 1.0                  *
7 *                    by AT&T Intellectual Property                     *
8 *                                                                      *
9 *                A copy of the License is available at                 *
10 *          http://www.eclipse.org/org/documents/epl-v10.html           *
11 *         (with md5 checksum b35adb5213ca9657e911e9befb180842)         *
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
sfmutex(Sfio_t * f,int type)31 int sfmutex(Sfio_t* f, int type)
32 #else
33 int sfmutex(f, type)
34 Sfio_t*	f;
35 int	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