[Libusb-devel] [PATCH] libusb-compat: Incompatible error messages in usb_detach_kernel_driver_np()

[Stanislav B. <sb...@su...>]

usb_detach_kernel_driver_np() from the compat library returns different
error messages than the old libusb0. It causes problems for drivers that
expect exact error code.

Proposed patch converts libusb1 errors to libusb0 errors. But maybe it
is overcomplicated. If we accept that the function was implemented only
in Linux (and the same is valid for libusb0), we can just simply return
original errno instead of double conversion of errno to libusb1 error
code and back to errno.

As an alternative, we can check only for -ENODATA condition as
libusb-compat does in usb_get_driver_np().

The affected software:
lirc-0.8.7/daemons/hw_srm7500libusb.c: srm7500_initialize_usbdongle()
The function continues if usb_detach_kernel_driver_np() finishes with no
error or if it returns -ENODATA. But the compat layer returns -ENOENT
and the driver considers this error as fatal.

I am waiting for confirmation of the fix.
Downstream bug reference:
https://bugzilla.novell.com/show_bug.cgi?id=683307

--- libusb/core.c
+++ libusb/core.c
@@ -912,6 +912,22 @@ API_EXPORTED int usb_get_driver_np(usb_d
 
 API_EXPORTED int usb_detach_kernel_driver_np(usb_dev_handle *dev, int interface)
 {
-	return compat_err(libusb_detach_kernel_driver(dev->handle, interface));
+	int r = compat_err(libusb_detach_kernel_driver(dev->handle, interface));
+	if (r == 0) {
+		return 0;
+	} else {
+		switch (r) {
+		case LIBUSB_ERROR_NOT_FOUND:
+			return ENODATA;
+		case LIBUSB_ERROR_INVALID_PARAM:
+			return EINVAL;
+		case LIBUSB_ERROR_NO_DEVICE:
+			return ENODEV;
+		case LIBUSB_ERROR_OTHER:
+			return errno;
+		default:
+			return ERANGE;
+		}
+	}
 }
 

-- 
Best Regards / S pozdravem,

Stanislav Brabec
software developer
---------------------------------------------------------------------
SUSE LINUX, s. r. o.                          e-mail: sb...@su...
Lihovarská 1060/12                            tel: +49 911 7405384547
190 00 Praha 9                                  fax: +420 284 028 951
Czech Republic                                    http://www.suse.cz/