I trying to use libusb on not rooted Nexus 5 as advised in this approach (by transferring usb file descriptor from java to native side).
My application ask permission via UsbManager.requestPermission and then run native method that call libusb_init to create libusb_context.
But libusb_init returns LIBUSB_ERROR_OTHER code (-99). After digging in the code I see why this happening. libusb reports 'could not find usbfs' because opendir("/dev/bus/usb") returns 0.
Also from adb shell I can't perform ls /dev, strange because I have rights (on Huawei U8950-1 with the same rights I can do this):
drwxr-xr-x root root 2014-09-04 10:26 dev
Looks like approach described below work not for all android devices. Can someone explain why?
There is already a fix in this libusb fork:
https://github.com/martinmarinov/rtl_tcp_andro-
Now, not only you will need to pass the file descriptor, you will need to pass the device file path as well via UsbDevice.getDeviceName().
Looks like Android L have an additional restriction about accessing to /dev deirectory. I have no more ideas about this
Update
Security Enhancements in Android 5.0
...
Android sandbox reinforced with SELinux. Android now requires SELinux in enforcing mode for all domains. SELinux is a mandatory access control (MAC) system in the Linux kernel used to augment the existing [discretionary access control (DAC) security] model](http://en.wikipedia.org/wiki/Discretionary_access_control). This new layer provides additional protection against potential security vulnerabilities.
...
Workarounds
- Install SELinuxModeChanger and change SELinux mode to
permissive - https://github.com/Gritzman/libusb
There is a custom libusb 1.0 which is capable of solving this issue by doing LibusbInit by passing the path of the usb device , this can bypass readdir command http://www.libusb.org/ download from the home webpage itself.
来源：https://stackoverflow.com/questions/25662307/android-l-libusb-init-returns-libusb-error-other-99