sfclrlock.c

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/* Copyright (c) Colorado School of Mines, 2006.*/
/* All rights reserved.                       */

#include	"sfhdr.h"

/*	Function to clear a locked stream.
**	This is useful for programs that longjmp from the mid of an sfio function.
**	There is no guarantee on data integrity in such a case.
**
**	Written by Kiem-Phong Vo
*/
#if __STD_C
int sfclrlock(reg Sfio_t* f)
#else
int sfclrlock(f)
reg Sfio_t	*f;
#endif
{
	int	rv;

	/* already closed */
	if(f && (f->mode&SF_AVAIL))
		return 0;

	SFMTXSTART(f,0);

	/* clear error bits */
	f->flags &= ~(SF_ERROR|SF_EOF);

	/* clear peek locks */
	if(f->mode&SF_PKRD)
	{	f->here -= f->endb-f->next;
		f->endb = f->next;
	}

	SFCLRBITS(f);

	/* throw away all lock bits except for stacking state SF_PUSH */
	f->mode &= (SF_RDWR|SF_INIT|SF_POOL|SF_PUSH|SF_SYNCED|SF_STDIO);

	rv = (f->mode&SF_PUSH) ? 0 : (f->flags&SF_FLAGS);

	SFMTXRETURN(f, rv);
}