#16 allow zero length control transfer (without buffer)

[mcuee]

https://sourceforge.net/p/libusb-win32/patches/16/

Using for instance libusbk.dll 3.0.7.0 (the version currently installed with Zadig) a control transfer with zero length will fail (see libusb/libusb#1006). I suspect this is due to the check on transfer_buffer_mdl in src/driver/ioctl.c since the same check for bulk transfer write is explicitly not done. The second patch changes the control transfer check to be consistent to the bulk transfer check.

The first patch just adds missing debug tags. The second patch applies on top.

I don't have the setup to rebuild and test libusb0.sys so I can only assume this is correct without verification by own testing. BTW this issue doesn't show when using the recently released libusbk.dll 3.0.8.0 because the control transfers are done differently here.

Driver error message caught with DebugView:
libusb0-sys:err [dispatch_ioctl] (null): invalid transfer request
patches.zip

[mcuee]

@tormodvolden Thanks a lot for the patches.
Please help to create a pull request here instead as we no longer use Sourceforge for development. Thanks.

[mcuee]

Reference: libusb/libusb#1006

Comments from @tormodvolden

I have been chasing this far into the woods of Windows dll's and drivers, and I believe to have found a bug in in libusb0.sys where it rejects zero-sized control writes in some cases where it shouldn't have to, and I have sent (https://sourceforge.net/p/libusb-win32/patches/16/) a patch upstream. But all this only to discover that libusk.dll 3.0.8.0 has changed its way of doing control transfer (thanks to mcuee/libusbk#15) so this bug doesn't surface any longer.

[tormodvolden]

Merge request in #22.
No problem, I didn't know it was moved to git and github. Can you please add a link on the SF page?

[mcuee]

Thanks. Updated the following page:
https://sourceforge.net/projects/libusb-win32/
https://sourceforge.net/p/libusb-win32/wiki/Home/