Re: [PATCH v2 06/11] git-gui: use git rev-parse for worktree discovery

> git gui uses a combination of tcl code and git invocations to determine
> the worktree and the location with respect to the worktree root
> (_prefix). But, git rev-parse provides all of this information directly,
> and assures full error and configuration checking are done by git
> itself. The entirety of discovery in normal configurations involves
> 
> 	git rev-parse --show-toplevel (gets worktree root)
> 	git rev-parse --show-prefix (shows location wrt the root)
> 
> An error thrown on either of these lines means the worktree discovered
> by git is unusable, or git did not discover a worktree because the
> current directory is inside the repository. If the user has defined
> GIT_DIR or GIT_WORK_TREE, this is a user configuration error and git-gui
> should stop.
> 
> Otherwise, the blame or browser subcommands can be used without a
> worktree.
> 
> A separate error might occur when changing to the root of the discovered
> worktree. The cause would be file system related and completely outside
> of git's control. So, the final "cd $worktree_root" is separately
> trapped.
> 
> Discovery of the repository and the worktree must be guarded to trap
> errors: the intent is that any configuration problems are caught during
> discovery, and later processing need not include error trapping and
> recovery. So, move all worktree discovery code to be immediately after
> repository discovery.
> 
> This does move configuration loading to occur after worktree discovery
> rather than before. None of the code executed in worktree discovery has
> any option controlled by a git-gui configuration variable, so no impact
> is expected. git itself will always read the repository configuration,
> including worktree specific configuration data if that exists, so this
> is unaffected by when git-gui loads its own config data, and we cannot
> be sure the full worktree dependent configuration can be loaded before
> full discovery is complete.

> 
> Signed-off-by: Mark Levedahl <mlevedahl@gmail.com>
> ---
>  git-gui.sh | 64 +++++++++++++++++++++++++-----------------------------
>  1 file changed, 30 insertions(+), 34 deletions(-)
> 
> diff --git a/git-gui.sh b/git-gui.sh
> index 936c309e59..8fe25fe188 100755
> --- a/git-gui.sh
> +++ b/git-gui.sh
> @@ -1164,6 +1164,36 @@ if {$_gitdir eq {}} {
>  	set picked 1
>  }
>  
> +# find worktree, continue without if not required
> +if {[catch {
> +	set _gitworktree [git rev-parse --show-toplevel]
> +	set _prefix [git rev-parse --show-prefix]
> +} err]} {
> +	if {[is_gitvars_error $err]} {
> +		exit 1
> +	}
> +	set _gitworktree {}
> +	set _prefix {}
> +}
> +
> +if {![is_bare]} {
> +	if {[catch {
> +		cd $_gitworktree
> +	} err]} {
> +		catch {wm withdraw .}
> +		error_popup [strcat [mc "Cannot change to discovered worktree: "] \
> +			"$_gitworktree" "\n\n$err"]
> +		exit 1;
> +	}
> +} elseif {![is_enabled bare]} {
> +	catch {wm withdraw .}
> +	error_popup [strcat [mc "Cannot use bare repository:"] "\n\n" $_gitdir]
> +	exit 1
> +}
> +
> +# repository and worktree config are complete, export them
> +set_gitdir_vars
> +
>  # Use object format as hash algorithm (either "sha1" or "sha256")
>  set hashalgorithm [git rev-parse --show-object-format]
>  if {$hashalgorithm eq "sha1"} {
> @@ -1179,37 +1209,6 @@ if {$hashalgorithm eq "sha1"} {
>  load_config 0
>  apply_config
>  
> -set _gitworktree [git rev-parse --show-toplevel]
> -
> -if {$_prefix ne {}} {
> -	if {$_gitworktree eq {}} {
> -		regsub -all {[^/]+/} $_prefix ../ cdup
> -	} else {
> -		set cdup $_gitworktree
> -	}
> -	if {[catch {cd $cdup} err]} {
> -		catch {wm withdraw .}
> -		error_popup [strcat [mc "Cannot move to top of working directory:"] "\n\n$err"]
> -		exit 1
> -	}
> -	set _gitworktree [pwd]
> -	unset cdup
> -} elseif {![is_enabled bare]} {
> -	if {[is_bare]} {
> -		catch {wm withdraw .}
> -		error_popup [strcat [mc "Cannot use bare repository:"] "\n\n$_gitdir"]
> -		exit 1
> -	}
> -	if {$_gitworktree eq {}} {
> -		set _gitworktree [file dirname $_gitdir]
> -	}
> -	if {[catch {cd $_gitworktree} err]} {
> -		catch {wm withdraw .}
> -		error_popup [strcat [mc "No working directory"] " $_gitworktree:\n\n$err"]
> -		exit 1
> -	}
> -	set _gitworktree [pwd]
> -}
>  set _reponame [file split [file normalize $_gitdir]]
>  if {[lindex $_reponame end] eq {.git}} {
>  	set _reponame [lindex $_reponame end-1]
> @@ -1217,9 +1216,6 @@ if {[lindex $_reponame end] eq {.git}} {
>  	set _reponame [lindex $_reponame end]
>  }
>  
> -# Export the final paths
> -set_gitdir_vars
> -
>  ######################################################################
>  ##
>  ## global init