Virtual File Provider

Virtual File Provider is a service which provides file descriptors which forward access requests to chrome. From the accessing process‘s perspective, the file descriptor behaves like a regular file descriptor (unlike pipe, it’s seekable), while actually there is no real file associated with it.

Private FUSE file system

To forward access requests on file descriptors, this service implements a FUSE file system which is only accessible to this service itself.

D-Bus interface

This service provides two D-Bus methods, GenerateVirtualFileId() and OpenFileById().

GenerateVirtualFileId() generates and returns a new unique ID, to be used for file descriptor (FD) creation on the private FUSE file system at a later stage. For ARCVM, this is achieved by directly issuing open() on the FUSE file system with the returned ID, whereas for ARC++ container, the FD is created by calling OpenFileById() below.

When OpenFileById() is called with a unique ID, in the ARC++ container flow, it creates and returns a seekable FD backed by the FUSE file system.

When the file descriptor created above is being accessed, Virtual File Provider will send signal to forward the access request to chrome.