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sfset.c

/***********************************************************************
*                                                                      *
*               This software is part of the ast package               *
*                  Copyright (c) 1985-2005 AT&T Corp.                  *
*                      and is licensed under the                       *
*                  Common Public License, Version 1.0                  *
*                            by AT&T Corp.                             *
*                                                                      *
*                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"

/*    Set some control flags or file descript for the stream
**
**    Written by Kiem-Phong Vo.
*/

#if __STD_C
int sfset(reg Sfio_t* f, reg int flags, reg int set)
#else
int sfset(f,flags,set)
reg Sfio_t* f;
reg int           flags;
reg int           set;
#endif
{
      reg int     oflags;

      SFMTXSTART(f,0);

      if(flags == 0 && set == 0)
            SFMTXRETURN(f, (f->flags&SF_FLAGS));

      if((oflags = (f->mode&SF_RDWR)) != (int)f->mode && _sfmode(f,oflags,0) < 0)
            SFMTXRETURN(f, 0);

      if(flags == 0)
            SFMTXRETURN(f, (f->flags&SF_FLAGS));

      SFLOCK(f,0);

      /* preserve at least one rd/wr flag */
      oflags = f->flags;
      if(!(f->bits&SF_BOTH) || (flags&SF_RDWR) == SF_RDWR )
            flags &= ~SF_RDWR;

      /* set the flag */
      if(set)
            f->flags |=  (flags&SF_SETS);
      else  f->flags &= ~(flags&SF_SETS);

      /* must have at least one of read/write */
      if(!(f->flags&SF_RDWR))
            f->flags |= (oflags&SF_RDWR);

      if(f->extent < 0)
            f->flags &= ~SF_APPENDWR;

      /* turn to appropriate mode as necessary */
      if((flags &= SF_RDWR) )
      {     if(!set)
            {     if(flags == SF_READ)
                        flags = SF_WRITE;
                  else  flags = SF_READ;
            }
            if((flags == SF_WRITE && !(f->mode&SF_WRITE)) ||
               (flags == SF_READ && !(f->mode&(SF_READ|SF_SYNCED))) )
                  (void)_sfmode(f,flags,1);
      }

      /* if not shared or unseekable, public means nothing */
      if(!(f->flags&SF_SHARE) || f->extent < 0)
            f->flags &= ~SF_PUBLIC;

      SFOPEN(f,0);
      SFMTXRETURN(f, (oflags&SF_FLAGS));
}

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