1*4887Schin /*********************************************************************** 2*4887Schin * * 3*4887Schin * This software is part of the ast package * 4*4887Schin * Copyright (c) 1985-2007 AT&T Knowledge Ventures * 5*4887Schin * and is licensed under the * 6*4887Schin * Common Public License, Version 1.0 * 7*4887Schin * by AT&T Knowledge Ventures * 8*4887Schin * * 9*4887Schin * A copy of the License is available at * 10*4887Schin * http://www.opensource.org/licenses/cpl1.0.txt * 11*4887Schin * (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9) * 12*4887Schin * * 13*4887Schin * Information and Software Systems Research * 14*4887Schin * AT&T Research * 15*4887Schin * Florham Park NJ * 16*4887Schin * * 17*4887Schin * Glenn Fowler <gsf@research.att.com> * 18*4887Schin * David Korn <dgk@research.att.com> * 19*4887Schin * Phong Vo <kpv@research.att.com> * 20*4887Schin * * 21*4887Schin ***********************************************************************/ 22*4887Schin #include "sfhdr.h" 23*4887Schin 24*4887Schin 25*4887Schin /* Push/pop streams 26*4887Schin ** 27*4887Schin ** Written by Kiem-Phong Vo. 28*4887Schin */ 29*4887Schin 30*4887Schin #define STKMTXLOCK(f1,f2) \ 31*4887Schin { if(f1) SFMTXLOCK(f1); \ 32*4887Schin if(f2) SFMTXLOCK(f2); \ 33*4887Schin } 34*4887Schin #define STKMTXRETURN(f1,f2,rv) \ 35*4887Schin { if(f1) SFMTXUNLOCK(f1); \ 36*4887Schin if(f2) SFMTXUNLOCK(f2); \ 37*4887Schin return(rv); \ 38*4887Schin } 39*4887Schin 40*4887Schin #if __STD_C 41*4887Schin Sfio_t* sfstack(Sfio_t* f1, Sfio_t* f2) 42*4887Schin #else 43*4887Schin Sfio_t* sfstack(f1,f2) 44*4887Schin Sfio_t* f1; /* base of stack */ 45*4887Schin Sfio_t* f2; /* top of stack */ 46*4887Schin #endif 47*4887Schin { 48*4887Schin reg int n; 49*4887Schin reg Sfio_t* rf; 50*4887Schin reg Sfrsrv_t* rsrv; 51*4887Schin reg Void_t* mtx; 52*4887Schin 53*4887Schin STKMTXLOCK(f1,f2); 54*4887Schin 55*4887Schin if(f1 && (f1->mode&SF_RDWR) != f1->mode && _sfmode(f1,0,0) < 0) 56*4887Schin STKMTXRETURN(f1,f2, NIL(Sfio_t*)); 57*4887Schin if(f2 && (f2->mode&SF_RDWR) != f2->mode && _sfmode(f2,0,0) < 0) 58*4887Schin STKMTXRETURN(f1,f2, NIL(Sfio_t*)); 59*4887Schin if(!f1) 60*4887Schin STKMTXRETURN(f1,f2, f2); 61*4887Schin 62*4887Schin /* give access to other internal functions */ 63*4887Schin _Sfstack = sfstack; 64*4887Schin 65*4887Schin if(f2 == SF_POPSTACK) 66*4887Schin { if(!(f2 = f1->push)) 67*4887Schin STKMTXRETURN(f1,f2, NIL(Sfio_t*)); 68*4887Schin f2->mode &= ~SF_PUSH; 69*4887Schin } 70*4887Schin else 71*4887Schin { if(f2->push) 72*4887Schin STKMTXRETURN(f1,f2, NIL(Sfio_t*)); 73*4887Schin if(f1->pool && f1->pool != &_Sfpool && f1->pool != f2->pool && 74*4887Schin f1 == f1->pool->sf[0]) 75*4887Schin { /* get something else to pool front since f1 will be locked */ 76*4887Schin for(n = 1; n < f1->pool->n_sf; ++n) 77*4887Schin { if(SFFROZEN(f1->pool->sf[n]) ) 78*4887Schin continue; 79*4887Schin (*_Sfpmove)(f1->pool->sf[n],0); 80*4887Schin break; 81*4887Schin } 82*4887Schin } 83*4887Schin } 84*4887Schin 85*4887Schin if(f2->pool && f2->pool != &_Sfpool && f2 != f2->pool->sf[0]) 86*4887Schin (*_Sfpmove)(f2,0); 87*4887Schin 88*4887Schin /* swap streams */ 89*4887Schin sfswap(f1,f2); 90*4887Schin 91*4887Schin /* but the reserved buffer and mutex must remain the same */ 92*4887Schin rsrv = f1->rsrv; f1->rsrv = f2->rsrv; f2->rsrv = rsrv; 93*4887Schin mtx = f1->mutex; f1->mutex = f2->mutex; f2->mutex = mtx; 94*4887Schin 95*4887Schin SFLOCK(f1,0); 96*4887Schin SFLOCK(f2,0); 97*4887Schin 98*4887Schin if(f2->push != f2) 99*4887Schin { /* freeze the pushed stream */ 100*4887Schin f2->mode |= SF_PUSH; 101*4887Schin f1->push = f2; 102*4887Schin rf = f1; 103*4887Schin } 104*4887Schin else 105*4887Schin { /* unfreeze the just exposed stream */ 106*4887Schin f1->mode &= ~SF_PUSH; 107*4887Schin f2->push = NIL(Sfio_t*); 108*4887Schin rf = f2; 109*4887Schin } 110*4887Schin 111*4887Schin SFOPEN(f1,0); 112*4887Schin SFOPEN(f2,0); 113*4887Schin 114*4887Schin STKMTXRETURN(f1,f2, rf); 115*4887Schin } 116