Re: [BUG] GIT_SSH_COMMAND is not being decomposed

From: Junio C Hamano <gitster@pobox.com>
Date: Apr 16, 2019, 04:24 UTC
Message-ID: <xmqqsguipofi.fsf@gitster-ct.c.googlers.com>
In-Reply-To: <008101d4f3db$56c20410$04460c30$@nexbridge.com>

"Randall S. Becker" <rsbecker@nexbridge.com> writes:

> As a suggestion, with people who know how to escape stuff properly
> (or not), perhaps we can select the alternate behaviour explicitly
> using a core.sshIgnoreEscape=true/false option. Thoughts on that?

The semantics of prepare_shell_cmd() is, regardless of any "funny characters" on the command line, the spawned command MUST behave AS IF it was run via the shell. The strcspn() trick is there merely as a low-level optimization so that we do not have to say

	sh -c a-single-token

which would be exactly the same as running

	a-single-token

The most typical use of that strcspn() trick is to ensure that

	GIT_SSH_COMMAND="the-command and its arguments"

would not attempt to run a command with a long and funny name "the-command and its arguments" somewhere on the $PATH without any parameter, and instead run

	sh -c "the-command and its arguments"

i.e. run the "the-command" with three parameters (and perhaps more built-in parameters prepared by the caller in the ssh connection codepath).