1 /*********************************************************************** 2 * * 3 * This software is part of the ast package * 4 * Copyright (c) 1985-2009 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 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