A terminal, IDE or service manager can leave descriptors open in the
launcher, and the guest inherited all of them. tools/exec-guest.py closes
every descriptor above stderr and then execs the guest command.
A shell loop over /proc/self/fd cannot do this portably: dash only parses
single-digit descriptors in redirections, so "exec 10>&-" runs a command
named 10 and ends the launcher on Debian and Ubuntu.
The launcher offline check now leaks descriptors 3, 4, 12 and 200 into the
launcher and asserts the guest sees only 0, 1 and 2. It runs in CI.
Split from #61.
Co-authored-by: DevWebeloper <[email protected]>
Co-Authored-By: Claude Opus 5.5 <[email protected]>
