"xpra --use-display" error-resistance

[pmarek]

xpra should do all necessary initializations _before_ taking over another display.

I just wanted to replace a hung xpra, and used the same commandline arguments - plus "--use-display". But that got the running session killed:

$ /usr/bin/xpra ...
cannot start - failed to create tcp socket: [Errno 98] The address is already in use
removing socket ...

because I may not use the same "--bind-tcp" address.

• perhaps the bound socket could be passed, like the Xvfb connection?
• try to get that socket bound _before_ taking over?
• In case of an error try to keep the Xvfb running (by starting a child that holds the socket?), to keep the applications alive

[Antoine Martin]

Yes, that may well be what caused other problems.

• Passing sockets is not going to happen.
• we could try to bind to sockets, etc, before taking over
• keep the Xvfb running: we want to avoid running the cleanups if we fail during startup and we have "--use-display", or maybe even always avoid killing the Xvfb when "--use-display" is used.

[Antoine Martin]

fixed in r1010: we start sockets before xvfb, tcp first so we don't clobber the unix domain socket if we fail to create the tcp socket