Initial revision

src/libbio/bseek.c

@@ -0,0 +1,56 @@
+#include	"lib9.h"
+#include	<bio.h>
+
+off_t
+Bseek(Biobuf *bp, off_t offset, int base)
+{
+	off_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) {
+			d = n - Boffset(bp);
+			bp->icount += d;
+			if(d >= 0) {
+				if(bp->icount <= 0)
+					return n;
+			} else {
+				if(bp->ebuf - bp->gbuf >= -bp->icount)
+					return n;
+			}
+		}
+
+		/*
+		 * reset the buffer
+		 */
+		n = lseek(bp->fid, n, base);
+		bp->icount = 0;
+		bp->gbuf = bp->ebuf;
+		break;
+
+	case Bwactive:
+		Bflush(bp);
+		n = lseek(bp->fid, offset, base);
+		break;
+	}
+	bp->offset = n;
+	return n;
+}