Follow-up from "_v2-entry-point: pass every environment variable"

@denittis wrote:

When inside a Flatpak container the socket fifo FD might be opened multiple times, for example from flatpak-spawn --host and from pressure-vessel-launcher.

@smcv wrote:

This is not ideal. The --info-fd protocol is meant to be: you read until EOF. flatpak-spawn should close all the fds after it has bounced them outside the container, so that it is not holding them open: otherwise, tricks like forwarding a fd that represents a locked resource won't work reliably.

We can do this for now, but one of us should send a MR to https://github.com/flatpak/flatpak-xdg-utils to make it close each fd in fd_list (except for stdin, stdout, stderr) before entering the main loop.

I think I might have copied the same bug into -launch, I'm not sure.

From a quick look it seems that also pressure-vessel-launch should be affected. I'm currently trying to glue together a small reproducer to be able to confirm the bug and use it as a validator for a possible fix.