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

> Hi,
> 
> On Fri, 27 Sep 2019, Pratyush Yadav wrote:
> 
> > On 26/09/19 10:46AM, Thomas Klaeger via GitGitGadget wrote:
> > > 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.
> 
> Except when Git GUI is installed in an unexpected location. This check
> is purely defensive programming.
> 
> >
> > > +		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.
> 
> That's not an option on Windows. `git-bash.exe` is not intended to be in
> the `PATH`, specifically not.
> 
> The implemented method is the best approach we found to determine the
> location of `git-bash.exe`.