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/***********************************************************************
* *
* This software is part of the ast package *
* Copyright (c) 1985-2009 AT&T Intellectual Property *
* and is licensed under the *
* Common Public License, Version 1.0 *
* by AT&T Intellectual Property *
* *
* A copy of the License is available at *
* http://www.opensource.org/licenses/cpl1.0.txt *
* (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9) *
* *
* Information and Software Systems Research *
* AT&T Research *
* Florham Park NJ *
* *
* Glenn Fowler <gsf@research.att.com> *
* David Korn <dgk@research.att.com> *
* Phong Vo <kpv@research.att.com> *
* *
***********************************************************************/
#include "sfhdr.h"
/* Push/pop streams
**
** Written by Kiem-Phong Vo.
*/
#define STKMTXLOCK(f1,f2) \
{ if(f1) SFMTXLOCK(f1); \
if(f2) SFMTXLOCK(f2); \
}
#define STKMTXRETURN(f1,f2,rv) \
{ if(f1) SFMTXUNLOCK(f1); \
if(f2) SFMTXUNLOCK(f2); \
return(rv); \
}
#if __STD_C
Sfio_t* sfstack(Sfio_t* f1, Sfio_t* f2)
#else
Sfio_t* sfstack(f1,f2)
Sfio_t* f1; /* base of stack */
Sfio_t* f2; /* top of stack */
#endif
{
reg int n;
reg Sfio_t* rf;
reg Sfrsrv_t* rsrv;
reg Void_t* mtx;
STKMTXLOCK(f1,f2);
if(f1 && (f1->mode&SF_RDWR) != f1->mode && _sfmode(f1,0,0) < 0)
STKMTXRETURN(f1,f2, NIL(Sfio_t*));
if(f2 && (f2->mode&SF_RDWR) != f2->mode && _sfmode(f2,0,0) < 0)
STKMTXRETURN(f1,f2, NIL(Sfio_t*));
if(!f1)
STKMTXRETURN(f1,f2, f2);
/* give access to other internal functions */
_Sfstack = sfstack;
if(f2 == SF_POPSTACK)
{ if(!(f2 = f1->push))
STKMTXRETURN(f1,f2, NIL(Sfio_t*));
f2->mode &= ~SF_PUSH;
}
else
{ if(f2->push)
STKMTXRETURN(f1,f2, NIL(Sfio_t*));
if(f1->pool && f1->pool != &_Sfpool && f1->pool != f2->pool &&
f1 == f1->pool->sf[0])
{ /* get something else to pool front since f1 will be locked */
for(n = 1; n < f1->pool->n_sf; ++n)
{ if(SFFROZEN(f1->pool->sf[n]) )
continue;
(*_Sfpmove)(f1->pool->sf[n],0);
break;
}
}
}
if(f2->pool && f2->pool != &_Sfpool && f2 != f2->pool->sf[0])
(*_Sfpmove)(f2,0);
/* swap streams */
sfswap(f1,f2);
/* but the reserved buffer and mutex must remain the same */
rsrv = f1->rsrv; f1->rsrv = f2->rsrv; f2->rsrv = rsrv;
mtx = f1->mutex; f1->mutex = f2->mutex; f2->mutex = mtx;
SFLOCK(f1,0);
SFLOCK(f2,0);
if(f2->push != f2)
{ /* freeze the pushed stream */
f2->mode |= SF_PUSH;
f1->push = f2;
rf = f1;
}
else
{ /* unfreeze the just exposed stream */
f1->mode &= ~SF_PUSH;
f2->push = NIL(Sfio_t*);
rf = f2;
}
SFOPEN(f1,0);
SFOPEN(f2,0);
STKMTXRETURN(f1,f2, rf);
}
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