Index: ulpt.c
===================================================================
RCS file: /usr/ncvs/src/sys/dev/usb/ulpt.c,v
retrieving revision 1.68
diff -u -r1.68 ulpt.c
--- ulpt.c	12 Nov 2005 17:39:31 -0000	1.68
+++ ulpt.c	24 Jan 2006 22:14:17 -0000
@@ -113,7 +113,9 @@
 	int sc_in;
 	usbd_pipe_handle sc_in_pipe;	/* bulk in pipe */
 	usbd_xfer_handle sc_in_xfer;
-	void *sc_in_buf;
+	char *sc_in_buf;		/* start of bulk read buffer */
+	char *sc_in_bp;			/* start of valid data in sc_in_buf */
+	int sc_in_len;			/* length of valid data at sc_in_bp */
 
 	usb_callout_t sc_read_callout;
 	int sc_has_callout;
@@ -584,6 +586,8 @@
 			usb_callout(sc->sc_read_callout, hz/5, ulpt_tick, sc);
 			sc->sc_has_callout = 1;
 		}
+		sc->sc_in_bp = NULL;
+		sc->sc_in_len = 0;
 	}
 
 	sc->sc_state = ULPT_OPEN;
@@ -726,33 +730,51 @@
 {
 	u_int32_t n, on;
 	int error = 0;
-	void *bufp;
+	char *bufp;
 	usbd_xfer_handle xfer;
 	usbd_status err;
 
-	DPRINTF(("ulptread\n"));
+	DPRINTF(("ulptread request %d\n", uio->uio_resid));
 
 	if (sc->sc_in_pipe == NULL)
 		return 0;
+	if (sc->sc_in_len != 0) {
+		n = min(sc->sc_in_len, uio->uio_resid);
+		error = uiomove(sc->sc_in_bp, n, uio);
+		if (error)
+		    return (error);
+		sc->sc_in_len -= n;
+		sc->sc_in_bp += n;
+		if (uio->uio_resid == 0)	/* read satisfied */
+		    return (error);
+	}
 
 	xfer = sc->sc_in_xfer;
 	bufp = sc->sc_in_buf;
-	while ((n = min(ULPT_BSIZE, uio->uio_resid)) != 0) {
-		DPRINTFN(1, ("ulptread: transfer %d bytes\n", n));
-		on = n;
+	
+	while (1) {
+		n = ULPT_BSIZE;
 		err = usbd_bulk_transfer(xfer, sc->sc_in_pipe,
 			  USBD_NO_COPY | USBD_SHORT_XFER_OK,
 			  USBD_NO_TIMEOUT, bufp, &n, "ulptrd");
 		if (err) {
 			DPRINTF(("ulptread: error=%d\n", err));
-			error = EIO;
-			break;
+			return (EIO);
 		}
-		error = uiomove(bufp, n, uio);
-		if (error)
+		DPRINTFN(1, ("ulptread: got %d bytes\n", n));
+		on = min(n, uio->uio_resid);
+		error = uiomove(bufp, on, uio);
+		if (error) {
+			sc->sc_in_bp = bufp;
+			sc->sc_in_len = n;
 			break;
-		if (on != n)
+		}
+		if (uio->uio_resid == 0 || n != ULPT_BSIZE) {
+			/* read satisfied or short read from printer */
+			sc->sc_in_bp = bufp + on;
+			sc->sc_in_len = n - on;
 			break;
+		}
 	}
 
 	return (error);