usb: use iovecs in USBPacket

Zap data pointer from USBPacket, add a QEMUIOVector instead.
Add a bunch of helper functions to manage USBPacket data.
Switch over users to the new interface.

Note that USBPacket->len was used for two purposes:  First to
pass in the buffer size and second to return the number of
transfered bytes or the status code on async transfers.  There
is a new result variable for the latter.  A new status code
was added to catch uninitialized result.

Nobody creates iovecs with more than one element (yet).
Some users are (temporarely) limited to iovecs with a single
element to keep the patch size as small as possible.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/hw/usb-wacom.c b/hw/usb-wacom.c
index d76ee97e49..25580067f2 100644
--- a/hw/usb-wacom.c
+++ b/hw/usb-wacom.c
@@ -308,6 +308,7 @@ static int usb_wacom_handle_control(USBDevice *dev, USBPacket *p,
 static int usb_wacom_handle_data(USBDevice *dev, USBPacket *p)
 {
     USBWacomState *s = (USBWacomState *) dev;
+    uint8_t buf[p->iov.size];
     int ret = 0;
 
     switch (p->pid) {
@@ -317,9 +318,10 @@ static int usb_wacom_handle_data(USBDevice *dev, USBPacket *p)
                 return USB_RET_NAK;
             s->changed = 0;
             if (s->mode == WACOM_MODE_HID)
-                ret = usb_mouse_poll(s, p->data, p->len);
+                ret = usb_mouse_poll(s, buf, p->iov.size);
             else if (s->mode == WACOM_MODE_WACOM)
-                ret = usb_wacom_poll(s, p->data, p->len);
+                ret = usb_wacom_poll(s, buf, p->iov.size);
+            usb_packet_copy(p, buf, ret);
             break;
         }
         /* Fall through.  */