Re: [PATCH 3/5] ssh: 'auto' variant to select between 'ssh' and 'simple'

On Mon, Oct 23, 2017 at 2:31 PM, Jonathan Nieder [off-list ref] wrote:

 1. First, check whether $GIT_SSH supports OpenSSH options by running

        $GIT_SSH -G <options> <host>

    This returns status 0 and prints configuration in OpenSSH if it
    recognizes all <options> and returns status 255 if it encounters
    an unrecognized option.  A wrapper script like

        exec ssh -- "$@"

    would fail with

        ssh: Could not resolve hostname -g: Name or service not known

capital -G?

-       if (variant == VARIANT_TORTOISEPLINK)
-               argv_array_push(&conn->args, "-batch");
+               detect.use_shell = conn->use_shell;

Why do we have to use a shell for evaluation of this
test balloon?

+               detect.no_stdin = detect.no_stdout = detect.no_stderr = 1;

okay.

...

+               argv_array_push(&detect.args, "-G");

...

+               variant = run_command(&detect) ? VARIANT_SIMPLE : VARIANT_SSH;

What if we have a VARIANT_SIMPLE, that doesn't care about -G
but just connects to the remote host (keeping the session open), do we need
to kill it after some time to have run_command return eventually?

Or can we give a command to be executed remotely (e.g. 'false') that
we know returns quickly?

 '

+test_expect_success 'OpenSSH-like uplink is treated as ssh' '
+       write_script "$TRASH_DIRECTORY/uplink" <<-EOF &&
+       if test "\$1" = "-G"

Reading this test (and the commit message) I realize, we do care
about the order of options, so this is fine.