RE: [Patch 1/3] connect.c: add nonstopssh variant to the sshVariant set.

From: Randall S. Becker <rsbecker@nexbridge.com>
Date: Jun 4, 2021, 20:35 UTC
Message-ID: <00f801d75981$29225c90$7b6715b0$@nexbridge.com>
In-Reply-To: <xmqqo8cl1k8s.fsf@gitster.g>

On June 4, 2021 3:52 PM, Junio C Hamano wrote:

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>"Randall S. Becker" <rsbecker@nexbridge.com> writes:
>> The primary
>> problem is supplying -S $ZSSH0 on the command line causes $ZSSH0 to be
>> resolved as a shell variable. It is not.
>
>I think we've heard that one before, and the whole thing sounds like you are saying that a command line
>
>    $ cmd $ZSSH0
>
>expects ZSSH0 to be a variable and tries to interpolate its value before passing it to "cmd" while you want "cmd" to see a literal

string that

>begins with a dollar sign.
>
>And the standard solution to that problem obviously is to tell the shell that the dollar-sign is not a reference to a variable by

quoting, by

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>using any variant of e.g.
>
>    $ cmd \$ZSSH0
>    $ cmd '$ZSSH0'
>    $ cmd "\$ZSSH0"

I'm going to have to retest this, but, when I last tried this, admittedly around git 2.0, what happened was that one level of escaping the $ worked for ls-remote, but we needed two levels for upload-pack which seemed to have two shells processing the command. I might be wrong about the specifics (been 4 years), but there was an inconsistency with the number of required escapes. The single quote did not work for upload-pack at the time. It is entirely possible that the second level indirection happened because the execution of the sshoss command itself cross over a platform boundary between the POSIX and non-POSIX file systems (it lives in the non-POSIX side).

>As far as I can tell, the code in connect.c that spawns ssh via GIT_SSH_COMMAND uses the pretty vanilla run_command() interface,

and

>that ought to be capable of producing such a command line, so I am lost as to where the need to have special case comes from.

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>"cmd" here may be "ssh" but run_command() should not care what exact command is being invoked.  I am puzzled why a simple quoting
>like the following cannot be adjusted for this particular case, for
>example:
>
>    $ cat >>.git/config <<\EOF
>    [alias]
>	cmdtest0 = "!echo ..\\$ZSSH0.."
>	cmdtest1 = "!echo ..$ZSSH0.."
>    EOF
>    $ ZSSH0=foo git cmdtest0
>    ..$ZSSH0..
>    $ ZSSH0=foo git cmdtest1
>    ..foo..

The multi-level resolution that I experienced is not covered in this situation. Still going to investigate this. I'm working on a different approach to extend my wrapper script to parse out the port, to supply to sshoss, which is not complaint with the standard ssh. If I have to stick with that script, there's no point going further on this variant.