/***********************************************************************
*                                                                      *
*               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"

/*	Synchronize data in buffers with the file system.
**	If f is nil, all streams are sync-ed
**
**	Written by Kiem-Phong Vo.
*/

#if __STD_C
static int _sfall(void)
#else
static int _sfall()
#endif
{
	reg Sfpool_t	*p, *next;
	reg Sfio_t*	f;
	reg int		n, rv;
	reg int		nsync, count, loop;
#define MAXLOOP 3

	for(loop = 0; loop < MAXLOOP; ++loop)
	{	rv = nsync = count = 0;
		for(p = &_Sfpool; p; p = next)
		{	/* find the next legitimate pool */
			for(next = p->next; next; next = next->next)
				if(next->n_sf > 0)
					break;

			/* walk the streams for _Sfpool only */
			for(n = 0; n < ((p == &_Sfpool) ? p->n_sf : 1); ++n)
			{	count += 1;
				f = p->sf[n];

				if(f->flags&SF_STRING )
					goto did_sync;
				if(SFFROZEN(f))
					continue;
				if((f->mode&SF_READ) && (f->mode&SF_SYNCED) )
					goto did_sync;
				if((f->mode&SF_READ) && !(f->bits&SF_MMAP) &&
				   f->next == f->endb)
					goto did_sync;
				if((f->mode&SF_WRITE) && !(f->bits&SF_HOLE) &&
				   f->next == f->data)
					goto did_sync;

				if(sfsync(f) < 0)
					rv = -1;

			did_sync:
				nsync += 1;
			}
		}

		if(nsync == count)
			break;
	}
	return rv;
}

#if __STD_C
int sfsync(reg Sfio_t* f)
#else
int sfsync(f)
reg Sfio_t*	f;	/* stream to be synchronized */
#endif
{
	int	local, rv, mode, lock;
	Sfio_t*	origf;

	if(!(origf = f) )
		return _sfall();

	SFMTXSTART(origf,-1);

	GETLOCAL(origf,local);

	if(origf->disc == _Sfudisc)	/* throw away ungetc */
		(void)sfclose((*_Sfstack)(origf,NIL(Sfio_t*)));

	rv = 0;

	lock = origf->mode&SF_LOCK;
	if(origf->mode == (SF_SYNCED|SF_READ) ) /* already synced */
		goto done;

	if((origf->mode&SF_RDWR) != SFMODE(origf,local) && _sfmode(origf,0,local) < 0)
	{	rv = -1;
		goto done;
	}

	for(; f; f = f->push)
	{	
		if((f->flags&SF_IOCHECK) && f->disc && f->disc->exceptf)
			(void)(*f->disc->exceptf)(f,SF_SYNC,(Void_t*)((int)1),f->disc);

		SFLOCK(f,local);

		/* pretend that this stream is not on a stack */
		mode = f->mode&SF_PUSH;
		f->mode &= ~SF_PUSH;

		/* these streams do not need synchronization */
		if((f->flags&SF_STRING) || (f->mode&SF_SYNCED))
			goto next;

		if((f->mode&SF_WRITE) && (f->next > f->data || (f->bits&SF_HOLE)) )
		{	/* sync the buffer, make sure pool don't move */
			reg int pool = f->mode&SF_POOL;
			f->mode &= ~SF_POOL;
			if(f->next > f->data && (SFWRALL(f), SFFLSBUF(f,-1)) < 0)
				rv = -1;
			if(!SFISNULL(f) && (f->bits&SF_HOLE) )
			{	/* realize a previously created hole of 0's */
				if(SFSK(f,(Sfoff_t)(-1),SEEK_CUR,f->disc) >= 0)
					(void)SFWR(f,"",1,f->disc);
				f->bits &= ~SF_HOLE;
			}
			f->mode |= pool;
		}

		if((f->mode&SF_READ) && f->extent >= 0 &&
		   ((f->bits&SF_MMAP) || f->next < f->endb) )
		{	/* make sure the file pointer is at the right place */
			f->here -= (f->endb-f->next);
			f->endr = f->endw = f->data;
			f->mode = SF_READ|SF_SYNCED|lock;
			(void)SFSK(f,f->here,SEEK_SET,f->disc);

			if((f->flags&SF_SHARE) && !(f->flags&SF_PUBLIC) &&
			   !(f->bits&SF_MMAP) )
			{	f->endb = f->next = f->data;
				f->mode &= ~SF_SYNCED;
			}
		}

	next:
		f->mode |= mode;
		SFOPEN(f,local);

		if((f->flags&SF_IOCHECK) && f->disc && f->disc->exceptf)
			(void)(*f->disc->exceptf)(f,SF_SYNC,(Void_t*)((int)0),f->disc);
	}

done:
	if(!local && f && (f->mode&SF_POOL) && f->pool && f != f->pool->sf[0])
		SFSYNC(f->pool->sf[0]);

	SFMTXRETURN(origf, rv);
}