xref: /titanic_41/usr/src/lib/libast/common/sfio/sfswap.c (revision e4f5a11d4a234623168c1558fcdf4341e11769e1)
1 /***********************************************************************
2 *                                                                      *
3 *               This software is part of the ast package               *
4 *          Copyright (c) 1985-2010 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 /*	Swap two streams. If the second argument is NULL,
25 **	a new stream will be created. Always return the second argument
26 **	or the new stream. Note that this function will always work
27 **	unless streams are locked by SF_PUSH.
28 **
29 **	Written by Kiem-Phong Vo.
30 */
31 
32 #if __STD_C
33 Sfio_t* sfswap(reg Sfio_t* f1, reg Sfio_t* f2)
34 #else
35 Sfio_t* sfswap(f1,f2)
36 reg Sfio_t*	f1;
37 reg Sfio_t*	f2;
38 #endif
39 {
40 	Sfio_t	tmp;
41 	int	f1pool, f2pool, f1mode, f2mode, f1flags, f2flags;
42 
43 	if(!f1 || (f1->mode&SF_AVAIL) || (SFFROZEN(f1) && (f1->mode&SF_PUSH)) )
44 		return NIL(Sfio_t*);
45 	if(f2 && SFFROZEN(f2) && (f2->mode&SF_PUSH) )
46 		return NIL(Sfio_t*);
47 	if(f1 == f2)
48 		return f2;
49 
50 	f1mode = f1->mode;
51 	SFLOCK(f1,0);
52 	f1->mode |= SF_PUSH;		/* make sure there is no recursion on f1 */
53 
54 	if(f2)
55 	{	f2mode = f2->mode;
56 		SFLOCK(f2,0);
57 		f2->mode |= SF_PUSH;	/* make sure there is no recursion on f2 */
58 	}
59 	else
60 	{	f2 = f1->file == 0 ? sfstdin :
61 		     f1->file == 1 ? sfstdout :
62 		     f1->file == 2 ? sfstderr : NIL(Sfio_t*);
63 		if((!f2 || !(f2->mode&SF_AVAIL)) )
64 		{	if(!(f2 = (Sfio_t*)malloc(sizeof(Sfio_t))) )
65 			{	f1->mode = f1mode;
66 				SFOPEN(f1,0);
67 				return NIL(Sfio_t*);
68 			}
69 
70 			SFCLEAR(f2,NIL(Vtmutex_t*));
71 		}
72 		f2->mode = SF_AVAIL|SF_LOCK;
73 		f2mode = SF_AVAIL;
74 	}
75 
76 	if(!f1->pool)
77 		f1pool = -1;
78 	else for(f1pool = f1->pool->n_sf-1; f1pool >= 0; --f1pool)
79 		if(f1->pool->sf[f1pool] == f1)
80 			break;
81 	if(!f2->pool)
82 		f2pool = -1;
83 	else for(f2pool = f2->pool->n_sf-1; f2pool >= 0; --f2pool)
84 		if(f2->pool->sf[f2pool] == f2)
85 			break;
86 
87 	f1flags = f1->flags;
88 	f2flags = f2->flags;
89 
90 	/* swap image and pool entries */
91 	memcpy((Void_t*)(&tmp),(Void_t*)f1,sizeof(Sfio_t));
92 	memcpy((Void_t*)f1,(Void_t*)f2,sizeof(Sfio_t));
93 	memcpy((Void_t*)f2,(Void_t*)(&tmp),sizeof(Sfio_t));
94 	if(f2pool >= 0)
95 		f1->pool->sf[f2pool] = f1;
96 	if(f1pool >= 0)
97 		f2->pool->sf[f1pool] = f2;
98 
99 	if(f2flags&SF_STATIC)
100 		f2->flags |= SF_STATIC;
101 	else	f2->flags &= ~SF_STATIC;
102 
103 	if(f1flags&SF_STATIC)
104 		f1->flags |= SF_STATIC;
105 	else	f1->flags &= ~SF_STATIC;
106 
107 	if(f2mode&SF_AVAIL)	/* swapping to a closed stream */
108 	{	if(!(f1->flags&SF_STATIC) )
109 			free(f1);
110 	}
111 	else
112 	{	f1->mode = f2mode;
113 		SFOPEN(f1,0);
114 	}
115 
116 	f2->mode = f1mode;
117 	SFOPEN(f2,0);
118 	return f2;
119 }
120