Re: Change Native Windows shell

From: brian m. carlson <sandals@crustytoothpaste.net>
Date: Jun 5, 2020, 00:00 UTC
Message-ID: <20200605000039.GB6569@camp.crustytoothpaste.net>
In-Reply-To: <CAAXzdLXt4+-34+OhS=Jn=-VeORN3Y2jMzzg9+bhyn88aN4hm0A@mail.gmail.com>

On 2020-06-04 at 23:33:16, Steven Penny wrote:

Show 19 quoted lines

> The Git pager is set up by the function `setup_pager` [1]. `setup_pager` calls
> `prepare_pager_args` [2]. `prepare_pager_args` sets `use_shell` [3]. Then
> `setup_pager` calls `start_command` [4]. Then, since `use_shell` has been
> defined, `prepare_shell_cmd` is called [5]. Finally, regardless of operating
> system, `sh` is called [6]:
> 
>     #ifndef GIT_WINDOWS_NATIVE
>                     argv_array_push(out, SHELL_PATH);
>     #else
>                     argv_array_push(out, "sh");
>     #endif
>                     argv_array_push(out, "-c");
> 
> The issue is, that it is possible to build a fully static native Windows
> Git [7]. A Git like this can run on a stock Windows system, with no requirement
> on MSYS2 or Cygwin. So it doesnt make sense for Git to be calling `sh`, when a
> user may not have or need `sh` on their system. I think that on Native Windows
> builds, that the Pager should be called directly, or if a shell must be used,
> then make it `cmd.exe` or `powershell.exe`.

This makes it impossible to write a configuration that works across platforms. CMD, PowerShell, and sh have entirely different quoting rules and functionality. The user would not be able to specify a pager or editor with arguments portably.

In addition, Git supports the EDITOR and VISUAL environment variables for editors and these always, 100% of the time, must be passed to sh to function correctly. It would be a bug if, when I used Windows, these variables were passed to CMD or PowerShell. People also use GIT_EDITOR or GIT_SEQUENCE_EDITOR for scripting changes to git rebase -i, and these also need to be interpreted in a portable way across systems, or programs will break.

Finally, Git needs sh for some commands, like git submodule, git bisect, git filter-branch, and others. While there's an effort to replace a lot of these with C because they don't perform very well on Windows, some of them are highly interactive and unlikely to be used for scripting, so porting them doesn't make a lot of sense.

If you really need Git functionality that doesn't rely on sh, you can look into libgit2 and its assorted language wrappers.

-- 
brian m. carlson: Houston, Texas, US
OpenPGP: https://keybase.io/bk2204