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 /* 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
sfswap(reg Sfio_t * f1,reg Sfio_t * f2)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