Re: [PATCH 1/1] git-gui (Windows): use git-bash.exe if it is available

From: Pratyush Yadav <me@yadavpratyush.com>
Date: Sep 26, 2019, 21:57 UTC
Message-ID: <20190926215737.aq4z2vhfrl6j634r@yadavpratyush.com>
In-Reply-To: <414cf2c89876fe122ee18f8d6533f083c2f65654.1569519977.git.gitgitgadget@gmail.com>

On 26/09/19 10:46AM, Thomas Klaeger via GitGitGadget wrote:

Show 25 quoted lines

> From: Thomas Klaeger <thklaeger@gmail.com>
> 
> Git for Windows 2.x ships with an executable that starts the Git Bash
> with all the environment variables and what not properly set up. It is
> also adjusted according to the Terminal emulator option chosen when
> installing Git for Windows (while `bash.exe --login -i` would always
> launch with Windows' default console).
> 
> So let's use that executable (usually C:\Program Files\Git\git-bash.exe)
> instead of `bash.exe --login -i` if its presence was detected.
> 
> This fixes https://github.com/git-for-windows/git/issues/490
> 
> Signed-off-by: Thomas Kläger <thomas.klaeger@10a.ch>
> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
> ---
>  git-gui.sh | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/git-gui.sh b/git-gui.sh
> index f9b323abff..5a1bfd736e 100755
> --- a/git-gui.sh
> +++ b/git-gui.sh
> @@ -2700,10 +2700,18 @@ if {![is_bare]} {
>  }

  
This hunk is kind of hard to understand. I'm writing what I make of it. 
Please correct me if I read it wrong.

Since this is a 4 year old commit not even authored by you, you might not have all the answers. That's OK. But I'd still like to point these things out. I do have a question at the end so please read the entire thing :)

>  if {[is_Windows]} {
> +	# Use /git-bash.exe if available
> +	set normalized [file normalize $::argv0]

argv0 would be the location of git-gui. We get an absolute path for the git-gui executable in the variable normalized.

> +	regsub "/mingw../libexec/git-core/git-gui$" \
> +		$normalized "/git-bash.exe" cmdLine

This finds the install location of git-bash by doing a string substitution. I'm assuming the path before /mingw.. is the installation directory of git, and so that's where git-bash would reside. We put that directory in cmdLine.

Nitpick: most of the code here uses snake case. So s/cmdLine/cmd_line/

> +	if {$cmdLine != $normalized && [file exists $cmdLine]} {

Why the $cmdLine != $normalized? When would they be equal? The string substitution should always change $cmdLine.

Show 12 quoted lines

> +		set cmdLine [list "Git Bash" $cmdLine &]
> +	} else {
> +		set cmdLine [list "Git Bash" bash --login -l &]
> +	}
>  	.mbar.repository add command \
>  		-label [mc "Git Bash"] \
> -		-command {eval exec [auto_execok start] \
> -					  [list "Git Bash" bash --login -l &]}
> +		-command {eval exec [auto_execok start] $cmdLine}
>  }
>  
>  if {[is_Windows] || ![is_bare]} {

The way of finding the path of git-bash is very hacky and would break as soon as there are any changes in the install locations. Plus, it is not at all easy to understand what's going on at first look.

Is there no better way of finding out git-bash's location? Is there something like the PATH environment variable in Windows that we can use to locate git-bash's executable? I have never developed in Windows so I have no idea how things work there.

On Linux for example, the exec() family of functions look into the PATH environment variable for the executable, so it is a pretty clean mechanism to execute programs.

-- 
Regards,
Pratyush Yadav