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- /*
- * 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>
- int64_t
- Bseek(Biobufhdr *bp, int64_t offset, int base)
- {
- int64_t 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;
- }
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