| chrome/browser/ash/usb |
| ====================== |
| |
| This directory contains the CrosUsbDetector, whose job it is to deal with devices that are plugged |
| into a chromeOS device - notifications of which come from the UsbDeviceManager Mojo service. |
| |
| Once a new device has been detected, CrosUsbDetector will first query permission_broker to see if |
| the device is allowed - either via device policy or via the rules which can allow or deny devices |
| based on various characteristics. CrosUsbDetector furthermore makes a decision if a user-facing |
| notification (of the form 'Share with Android/Linux') should be shown, or if the device will be made |
| silently available via the settings pages. |
| |
| If a user elects to share a device (in this case via the notification, as the settings flow is |
| handled elsewhere), the flow is roughly: AttachUsbDeviceToGuest() -> UnmountFilesystems() -> |
| OnUnmountFilesystems() -> AttachAfterDetach() -> OnAttachUsbDeviceOpened() -> DoVmAttach() -> |
| OnUsbDeviceAttachFinished(). A more thorough depiction of the flow can be seen below: |
| |
|  |
| |
| Things to note: |
| - permission_broker is actually asked twice if it is ok with a device being shared, once upon new |
| device detection and then once more upon the request to share it / pass it through. |
| - CrosUsbDetector also keeps a list of USB classes which it does not wish to be passed through, and |
| these are used to create an interface mask that permission_broker uses to drop those interfaces when |
| passing the device through. |
