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
25 /* Push/pop streams
26 **
27 ** Written by Kiem-Phong Vo.
28 */
29
30 #define STKMTXLOCK(f1,f2) \
31 { if(f1) SFMTXLOCK(f1); \
32 if(f2) SFMTXLOCK(f2); \
33 }
34 #define STKMTXRETURN(f1,f2,rv) \
35 { if(f1) SFMTXUNLOCK(f1); \
36 if(f2) SFMTXUNLOCK(f2); \
37 return(rv); \
38 }
39
40 #if __STD_C
sfstack(Sfio_t * f1,Sfio_t * f2)41 Sfio_t* sfstack(Sfio_t* f1, Sfio_t* f2)
42 #else
43 Sfio_t* sfstack(f1,f2)
44 Sfio_t* f1; /* base of stack */
45 Sfio_t* f2; /* top of stack */
46 #endif
47 {
48 reg int n;
49 reg Sfio_t* rf;
50 reg Sfrsrv_t* rsrv;
51 reg Void_t* mtx;
52
53 STKMTXLOCK(f1,f2);
54
55 if(f1 && (f1->mode&SF_RDWR) != f1->mode && _sfmode(f1,0,0) < 0)
56 STKMTXRETURN(f1,f2, NIL(Sfio_t*));
57 if(f2 && (f2->mode&SF_RDWR) != f2->mode && _sfmode(f2,0,0) < 0)
58 STKMTXRETURN(f1,f2, NIL(Sfio_t*));
59 if(!f1)
60 STKMTXRETURN(f1,f2, f2);
61
62 /* give access to other internal functions */
63 _Sfstack = sfstack;
64
65 if(f2 == SF_POPSTACK)
66 { if(!(f2 = f1->push))
67 STKMTXRETURN(f1,f2, NIL(Sfio_t*));
68 f2->mode &= ~SF_PUSH;
69 }
70 else
71 { if(f2->push)
72 STKMTXRETURN(f1,f2, NIL(Sfio_t*));
73 if(f1->pool && f1->pool != &_Sfpool && f1->pool != f2->pool &&
74 f1 == f1->pool->sf[0])
75 { /* get something else to pool front since f1 will be locked */
76 for(n = 1; n < f1->pool->n_sf; ++n)
77 { if(SFFROZEN(f1->pool->sf[n]) )
78 continue;
79 (*_Sfpmove)(f1->pool->sf[n],0);
80 break;
81 }
82 }
83 }
84
85 if(f2->pool && f2->pool != &_Sfpool && f2 != f2->pool->sf[0])
86 (*_Sfpmove)(f2,0);
87
88 /* swap streams */
89 sfswap(f1,f2);
90
91 /* but the reserved buffer and mutex must remain the same */
92 rsrv = f1->rsrv; f1->rsrv = f2->rsrv; f2->rsrv = rsrv;
93 mtx = f1->mutex; f1->mutex = f2->mutex; f2->mutex = mtx;
94
95 SFLOCK(f1,0);
96 SFLOCK(f2,0);
97
98 if(f2->push != f2)
99 { /* freeze the pushed stream */
100 f2->mode |= SF_PUSH;
101 f1->push = f2;
102 rf = f1;
103 }
104 else
105 { /* unfreeze the just exposed stream */
106 f1->mode &= ~SF_PUSH;
107 f2->push = NIL(Sfio_t*);
108 rf = f2;
109 }
110
111 SFOPEN(f1,0);
112 SFOPEN(f2,0);
113
114 STKMTXRETURN(f1,f2, rf);
115 }
116