Fix early stdio close due to multiple ownership

[mgjm]

What type of PR is this?

/kind bug

What this PR does / why we need it:

The ContainerIO::read_loop_stdin function was taking the fd to stdin as a RawFd and took ownership of the file descriptor. This worked for piped IO (streams.rs) but not for tty based IO (terminal.rs).

With tty based IO the same file descriptor was used as an AsyncFd and passed to read_loop_stdin this resulted in two owners of the same file descriptor. The first owner (stdin in most cases) would close the fd on drop. The second owner would stall as it won't be notified that the fd closed and once the second owner would drop it would try to close the same fd again. Which could have been reused in the meantime.

This change refactors ContainerIO::read_loop_stdin to take an implementation of AsyncWrite and introduces a new TerminalFd which wraps the pty file descriptor and implements AsyncRead and AsyncWrite for references to itself. This allows us to use reference counting to close the file descriptor only after both the read_loop_stdin and read_loop terminate.

Which issue(s) this PR fixes:

None

Special notes for your reviewer:

Does this PR introduce a user-facing change?

None

[saschagrunert]

That's a good one, thank you for this fix!

@haircommander @rphillips PTAL

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: mgjm, saschagrunert

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[haircommander]

/lgtm

great find!