common/sfio/sfstack.c

da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin/***********************************************************************
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin*                                                                      *
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin*               This software is part of the ast package               *
3e14f97f673e8a630f076077de35afdd43dc1587Roger A. Faulkner*          Copyright (c) 1985-2010 AT&T Intellectual Property          *
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin*                      and is licensed under the                       *
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin*                  Common Public License, Version 1.0                  *
7c2fbfb345896881c631598ee3852ce9ce33fb07April Chin*                    by AT&T Intellectual Property                     *
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin*                                                                      *
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin*                A copy of the License is available at                 *
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin*            http://www.opensource.org/licenses/cpl1.0.txt             *
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin*         (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9)         *
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin*                                                                      *
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin*              Information and Software Systems Research               *
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin*                            AT&T Research                             *
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin*                           Florham Park NJ                            *
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin*                                                                      *
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin*                 Glenn Fowler <gsf@research.att.com>                  *
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin*                  David Korn <dgk@research.att.com>                   *
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin*                   Phong Vo <kpv@research.att.com>                    *
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin*                                                                      *
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin***********************************************************************/
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin#include    "sfhdr.h"
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin/*  Push/pop streams
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin**
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin**  Written by Kiem-Phong Vo.
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin*/
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin#define STKMTXLOCK(f1,f2) \
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin    { if(f1) SFMTXLOCK(f1); \
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin      if(f2) SFMTXLOCK(f2); \
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin    }
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin#define STKMTXRETURN(f1,f2,rv) \
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin    { if(f1) SFMTXUNLOCK(f1); \
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin      if(f2) SFMTXUNLOCK(f2); \
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin      return(rv); \
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin    }
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin#if __STD_C
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chinSfio_t* sfstack(Sfio_t* f1, Sfio_t* f2)
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin#else
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chinSfio_t* sfstack(f1,f2)
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chinSfio_t* f1; /* base of stack    */
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chinSfio_t* f2; /* top of stack */
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin#endif
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin{
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin    reg int     n;
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin    reg Sfio_t* rf;
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin    reg Sfrsrv_t*   rsrv;
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin    reg Void_t* mtx;
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin    STKMTXLOCK(f1,f2);
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin    if(f1 && (f1->mode&SF_RDWR) != f1->mode && _sfmode(f1,0,0) < 0)
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin        STKMTXRETURN(f1,f2, NIL(Sfio_t*));
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin    if(f2 && (f2->mode&SF_RDWR) != f2->mode && _sfmode(f2,0,0) < 0)
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin        STKMTXRETURN(f1,f2, NIL(Sfio_t*));
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin    if(!f1)
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin        STKMTXRETURN(f1,f2, f2);
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin    /* give access to other internal functions */
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin    _Sfstack = sfstack;
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin    if(f2 == SF_POPSTACK)
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin    {   if(!(f2 = f1->push))
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin            STKMTXRETURN(f1,f2, NIL(Sfio_t*));
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin        f2->mode &= ~SF_PUSH;
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin    }
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin    else
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin    {   if(f2->push)
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin            STKMTXRETURN(f1,f2, NIL(Sfio_t*));
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin        if(f1->pool && f1->pool != &_Sfpool && f1->pool != f2->pool &&
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin           f1 == f1->pool->sf[0])
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin        {   /* get something else to pool front since f1 will be locked */
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin            for(n = 1; n < f1->pool->n_sf; ++n)
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin            {   if(SFFROZEN(f1->pool->sf[n]) )
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin                    continue;
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin                (*_Sfpmove)(f1->pool->sf[n],0);
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin                break;
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin            }
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin        }
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin    }
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin    if(f2->pool && f2->pool != &_Sfpool && f2 != f2->pool->sf[0])
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin        (*_Sfpmove)(f2,0);
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin    /* swap streams */
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin    sfswap(f1,f2);
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin    /* but the reserved buffer and mutex must remain the same */
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin    rsrv = f1->rsrv; f1->rsrv = f2->rsrv; f2->rsrv = rsrv;
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin    mtx = f1->mutex; f1->mutex = f2->mutex; f2->mutex = mtx;
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin    SFLOCK(f1,0);
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin    SFLOCK(f2,0);
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin    if(f2->push != f2)
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin    {   /* freeze the pushed stream */
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin        f2->mode |= SF_PUSH;
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin        f1->push = f2;
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin        rf = f1;
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin    }
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin    else
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin    {   /* unfreeze the just exposed stream */
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin        f1->mode &= ~SF_PUSH;
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin        f2->push = NIL(Sfio_t*);
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin        rf = f2;
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin    }
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin    SFOPEN(f1,0);
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin    SFOPEN(f2,0);
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin    STKMTXRETURN(f1,f2, rf);
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin}