[Libusb-devel] libusb and possible linux devio.c bug

[<gn...@is...>]

The function usb_control_msg() in libusb can't seem to
handle control messages with recipient of zero. The errno
value returned is ENOENT (2). I traced it down to a
possible linux bug in the usb driver code. The endpoint
check in devio.c and function check_ctrlrecip() is where
the endpoint zero is rejected. I looked at kernels from
the 2.4.x and 2.6.x series. Can someone verify that this
is a valid USB request and that the driver is broken?
Thanx.

=======================================================
After open/claim with libusb, here's the calling function:

void
GetStatus(usb_dev_handle *devhandle, int which)
{
         unsigned char gotdat[64];
         int ret, index;

         printf("Retrieving status for endpoint 0x%x... ", which);

         // should work with 0x0 endpoint with fixed bug in linux
         ret = usb_control_msg(devhandle,
                         USB_ENDPOINT_IN | USB_RECIP_ENDPOINT,
                         USB_REQ_GET_STATUS,
                         0, which, gotdat, 2, 1000);
         if (ret > 0)
         {
                 printf("\nStatus data: ");
                 for (index = 0; index < ret; index++)
                         printf("\t0x%x", gotdat[index]);
         }
         else if (ret < 0)
                 printf("\nUSB error code %d: %s\n", ret,
			usb_strerror());
         else
                 printf("\n");

         printf("\n");
}


=======================================================
Here's the possible problem in the linux usb code with fix
in .....drivers/usb/devio.c:

static int check_ctrlrecip(struct dev_state *ps, unsigned int 
requesttype, unsigned int index)
{
         int ret;

         if (USB_TYPE_VENDOR == (USB_TYPE_MASK & requesttype))
                 return 0;

         switch (requesttype & USB_RECIP_MASK) {
         case USB_RECIP_ENDPOINT:
#if 1
                 if ((index & ~USB_ENDPOINT_DIR_MASK) == 0) /* ep 0 OK 
for control */
                         break;
#endif
                 if ((ret = findintfep(ps->dev, index & 0xff)) < 0)
                         return ret;
                 if ((ret = checkintf(ps, ret)))
                         return ret;
                 break;

         case USB_RECIP_INTERFACE:
                 if ((ret = findintfif(ps->dev, index & 0xff)) < 0)
                         return ret;
                 if ((ret = checkintf(ps, ret)))
                         return ret;
                 break;
         }
         return 0;
}