This was a requested feature. To make sure that FEXServer is running and
managed by a parent process, we need to have a way to tell FEXServer to
keep alive without any FEX clients. The best way to do this is to pass
FEXServer a Pipe (like FEX does when a client starts it), but instead of
FEXServer signaling to FEXInterpreter that it's ready. FEXServer listens
to the pipe to see if the management process is still alive.
The expectation here is that the management process passes FEXServer the
read end of a pipe, and when the management software is done (or gets
killed by the kernel!) then the write end of the pipe is closed, and
FEXServer naturally closes (As long as there's no FEX processes
remaining).
Abstract sockets have one limitation: they are bound to a network
namespace. Chromium/CEF sandboxes using a new netns, which breaks
connecting to the FEXServer.
To work around this, use and try *both* abstract and named sockets. As
long as either the filesystem or the network is unsandboxed, things will
work. If both are sandboxed, there isn't much we can do... but at that
point we shouldn't be reinitializing the FEXServer connection anyway
since the FS should be available on FEXInterpreter startup.
This is a relatively invasive change since multiple things needed to
happen at once.
* Socket based logging is removed
* Logging has been replaced to only support stdout, stderr, and server
* Server is now default and replaces what FEXLogServer did
* Server logging now uses a pipe instead of a socket
* Can be faster than stderr and stdout since the application doesn't
need to wait on terminal output
* FEXMountDaemon has been removed
* Functionality has been merged in to FEXServer
* FEXServer is always executed on FEX initialization time
* Similar in behaviour to Wine's wineserver
* Can explicitly start this before using FEX for logging purposes
* Stays around until all instances of FEX exit
* Will stick around for a short amount of time in case of spurious
execution
* FEXServer will soon be extended to do more than logging and squashfs
mounting
* FEX rootfs scripts will need to be updated to support this path
* Just means rbinding the /tmp folder and forcing a FEXServer instance
to be alive
* Pressure-vessel works fine in this case since FEXServer will already
be running
* It already rbinds the host /tmp folder which is why this works
Ryan Houdek