Import sources from 2011-03-30 iso image

1 files changed, 58 insertions, 0 deletions

diff --git a/sys/src/libbio/bseek.c b/sys/src/libbio/bseek.c
new file mode 100755
index 000000000..809b09323
--- /dev/null
+++ b/sys/src/libbio/bseek.c
@@ -0,0 +1,58 @@
+#include	<u.h>
+#include	<libc.h>
+#include	<bio.h>
+
+vlong
+Bseek(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;
+}