Android L | libusb_init返回LIBUSB_ERROR_OTHER（-99）

Question

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?

Answer 1

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().

Answer 2

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

1. Install SELinuxModeChanger and change SELinux mode to permissive
2. https://github.com/Gritzman/libusb

Answer 3

有一个自定义libusb 1.0能够通过传递usb设备的路径来执行LibusbInit来解决这个问题，这可以绕过来自主页网页本身的readdir命令http://www.libusb.org/ download。