/*  * This file is part of the UCB release of Plan 9. It is subject to the license * terms in the LICENSE file found in the top-level directory of this * distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No * part of the UCB release of Plan 9, including this file, may be copied, * modified, propagated, or distributed except according to the terms contained * in the LICENSE file. */ #include	<u.h>#include	<libc.h>#include	<bio.h> vlongBseek(Biobufhdr *bp, vlong offset, int base){	vlong n, d; 	switch(bp->state) {	default:		fprint(2, "Bseek: unknown state %d\n", bp->state);		return Beof; 	case Bracteof:		bp->state = Bractive;		bp->icount = 0;		bp->gbuf = bp->ebuf; 	case Bractive:		n = offset;		if(base == 1) {			n += Boffset(bp);			base = 0;		} 		/*		 * try to seek within buffer		 */		if(base == 0) {			/*			 * if d is too large for an int, icount may wrap,			 * so we need to ensure that icount hasn't wrapped			 * and points within the buffer's valid data.			 */			d = n - Boffset(bp);			bp->icount += d;			if(d <= bp->bsize && bp->icount <= 0 &&			    bp->ebuf - bp->gbuf >= -bp->icount)				return n;		} 		/*		 * reset the buffer		 */		n = seek(bp->fid, n, base);		bp->icount = 0;		bp->gbuf = bp->ebuf;		break; 	case Bwactive:		Bflush(bp);		n = seek(bp->fid, offset, base);		break;	}	bp->offset = n;	return n;}