/***********************************************************************
*                                                                      *
*               This software is part of the ast package               *
*           Copyright (c) 1985-2007 AT&T Knowledge Ventures            *
*                      and is licensed under the                       *
*                  Common Public License, Version 1.0                  *
*                      by AT&T Knowledge Ventures                      *
*                                                                      *
*                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));
}