Cannot read a UsbFile content

[auloma04]

Hello everyone. I am trying to read the content of my USB device.

I can successfully list the content of the USB key, list files etc ..
I am supposed to have a file named "network.ini" on the USB key. The file is well listed

Problem

When I try to read the content of the file, i get the error: java.io.IOException: MAX_RECOVERY_ATTEMPTS Exceeded while trying to transfer command to device, please reattach device and try again
After having looked at the logcat, I saw that the Stack trace of the error mentions the error : System.err: Caused by: java.io.IOException: Could not read from device, result == -1 errno 0 null

So following the documentation advices, I tried to use libusb:

• Adding the right implementation in gradle dependencies
• Adding at the begining of my MainActivity:

UsbCommunicationFactory.registerCommunication(new LibusbCommunicationCreator());
UsbCommunicationFactory.setUnderlyingUsbCommunication(UsbCommunicationFactory.UnderlyingUsbCommunication.OTHER);

An still get an error when try to read the InputStream: java.io.IOException: MAX_RECOVERY_ATTEMPTS Exceeded while trying to transfer command to device, please reattach device and try again
But this time logcat is not pointing the same one on the stack trace: Caused by: me.jahnen.libaums.libusbcommunication.LibusbException: libusb control transfer failed: Input/output error [-1]

Expected behavior

What I want is to convert the content of the file into a String. (its content is very light)

How I do that after having accessed the fileSystem of the UsbMassStorageDevice:

public void readFs(FileSystem fs) throws IOException {
        Log.d(TAG, "Capacity: " + fs.getCapacity());
        Log.d(TAG, "Occupied Space: " + fs.getOccupiedSpace());
        Log.d(TAG, "Free Space: " + fs.getFreeSpace());
        Log.d(TAG, "Chunk size: " + fs.getChunkSize());

        UsbFile root = fs.getRootDirectory();

        UsbFile[] files = root.listFiles();
        for(UsbFile file: files) {
            Log.d(TAG, "File:" + file.getName() + " is a dir: " + file.isDirectory());
            if(!file.isDirectory()) {
                readFile(file, fs);
            }
        }
    }

    public void readFile(UsbFile file, FileSystem fs) throws IOException {
        Log.d(TAG, "readFile: " + file.getName());
        InputStream is = UsbFileStreamFactory.createBufferedInputStream(file, fs);
        byte[] buffer = new byte[fs.getChunkSize()];

        is.read(buffer);
    }

I spent a lot of time on this issue and have no more ideas to solve this quite urgent problem ...
Thanks for your help

[auloma04]

Github for reproduction: https://github.com/auloma04/android-usb-reader

[magnusja]

• Try not using libusb but the Android communication, does that work?
• Try a different OTG adapter. Sometimes these are not the best for stable communication.

Unfortunately, it looks like a low level communication errror. So not much I can help. Do other apps allowing USB access work?