libusb: error [op_open] getcap failed in C++ on Linux

Question

I am running into trouble calling libusb_open in C++ on Linux (running on Raspberry Pi but virtualized to x86 using Exagear).

I can find a device using libusb_get_device_list but it appears translating a device to a device handler using libusb_open is causing problems, even though it returns a 0 (success), however no further commands work. It is giving me the error:

libusb: error [op_open] getcap failed (22)

UPDATE

A little bit of digging has revealed that the following command is producing the error (within libusb):

r = ioctl(hpriv->fd, IOCTL_USBFS_GET_CAPABILITIES, &hpriv->caps);

where IOCTL_USBFS_GET_CAPABILITIES is _IOR('U', 26, __u32). Digging has revealed that error 22 from ioctl is an invalid argument. I'm still trying to unpick this, but any help here is greatly appreciated.

question from:https://stackoverflow.com/questions/41504792/libusb-error-op-open-getcap-failed-in-c-on-linux

Answer 1

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