git-gui: Allow users to choose/create/clone a repository

If we are started outside of a git repository than it is likely
the user started us from some sort of desktop shortcut icon in
the operating system.  In such a case the user is expecting us to
prompt them to locate the git repository they want to work on,
or to help them make a new repository, or to clone one from an
existing location.  This is a very simple wizard that offers the
user one of these three choices.

When we clone a repository we always use the name `master` in the
local repository, even if the remote side does not appear to point
to that name.  I chose this as a policy decision.  Much of the Git
documentation talks about `master` being the default branch in a
repository and that's what git-init does too.  If the remote side
doesn't call its default branch `master` most users just don't care,
they just want to use Git the way the documentation describes.

Rather than relying on the git-clone Porcelain that ships with
git we build the new repository ourselves and then obtain content
by git-fetch.  This technique simplifies the entire clone process
to roughly: `git init && git fetch && git pull`.  Today we use
three passes with git-fetch; the first pass gets us the bulk of
the objects and the branches, the second pass gets us the tags,
and the final pass gets us the current value of HEAD to initialize
the default branch.

If the source repository is on the local disk we try to use a
hardlink to connect the objects into the new clone as this can
be many times faster than copying the objects or packing them and
passing the data through a pipe to index-pack.  Unlike git-clone
we stick to pure Tcl [file link -hard] operation thus avoiding the
need to fork a cpio process to setup the hardlinks.  If hardlinks
do not appear to be supported (e.g. filesystem doesn't allow them or
we are crossing filesystem boundaries) we use file copying instead.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

2 files changed, 841 insertions, 3 deletions

diff --git a/git-gui.sh b/git-gui.sh
index 3ddfcd50eb..37da8fde3b 100755
--- a/git-gui.sh
+++ b/git-gui.sh
@@ -833,9 +833,9 @@ if {[catch {
 		set _gitdir [git rev-parse --git-dir]
 		set _prefix [git rev-parse --show-prefix]
 	} err]} {
-	catch {wm withdraw .}
-	error_popup [strcat [mc "Cannot find the git directory:"] "\n\n$err"]
-	exit 1
+	load_config 1
+	apply_config
+	choose_repository::pick
 }
 if {![file isdirectory $_gitdir] && [is_Cygwin]} {
 	catch {set _gitdir [exec cygpath --windows $_gitdir]}
diff --git a/lib/choose_repository.tcl b/lib/choose_repository.tcl
new file mode 100644
index 0000000000..1bec8bd0a8
--- /dev/null
+++ b/lib/choose_repository.tcl
@@ -0,0 +1,838 @@
+# git-gui Git repository chooser
+# Copyright (C) 2007 Shawn Pearce
+
+class choose_repository {
+
+image create photo ::choose_repository::git_logo -data {
+R0lGODlh3wA9AMIHAMAAAMIKCsMKCgCAAN/v3/319f///wAAACH5BAEKAAcALAAAAADfAD0AAAP+
+aLrc/jDKSau9OOvNu/9gKI5kaZ5oqq5s675wLM90bd94ru987//AoHBILBqPyKSSFGg6n9BoUwCR
+Wq3Ux3X7zC4Xg7B4HN4Bzui0eo2GsN9wN3ye/jLI+IGZzpfz535/b3ZgeWN7goMPiXGLjGyECoaH
+Oo+QjpZ1mJlnkQaTYhigZR6cmg6mbZucnqN6F64fqZ2rmYGskbGwo7Kzt7a1lq28u6AfBcjJysvM
+yRDN0NHP0dTKniS619pG2dveQd3f4jzh40eu3eh5EOrq5kPtk3fxoQ/0xO9A93jz9+z7hvKBA1hP
+0r5/BMkIJIfvU0OE8opFXDjQWCGLEsplfEj+sUc6jg40RhDZMcdHjCNBpkQ5IuAHlx5gtjg5cWVN
+CiRjrnu5Uye/FzRlQhQ6IWcHohqQZlCKImhPm0ztqeT506dCqlddOK0K9SnOqVYphS141OuKrVm7
+cv3KUkRUC28rxMXW0KjDthvxgphb1GxSvynQilWblu1Nt4BFJZY4mIVgskMXhwQrN+GryQkj+zvx
+mFTew5/5Eo6nmV5p0pzrUr4LejTkv5mlxsZMsKlqvf1an3691PJud7JrpwZFoDgBu3Zzi/6NjrlI
+y5cD+74IPbrydowPBgfofPXe6QarW6eOuvLsBtC7424JnnX67djhtr++mTb3s+3Fe0avvexl2g3L
+laaPd4QECN9+HBioFYF2KMjff7AVtkNyBUpmnoQRNjYhg184SN94GfI2U38LeUieiIpBOGJ9JVpo
+mIYhIggUiQKZGB6GvanoGI0l9ejjj0AGKeSQRBZp5JFIJqnkkkxOkAAAOw==
+}
+
+field top
+field w
+field w_body      ; # Widget holding the center content
+field w_next      ; # Next button
+field o_cons      ; # Console object (if active)
+field w_types     ; # List of type buttons in clone
+
+field action          new ; # What action are we going to perform?
+field done              0 ; # Finished picking the repository?
+field local_path       {} ; # Where this repository is locally
+field origin_url       {} ; # Where we are cloning from
+field origin_name  origin ; # What we shall call 'origin'
+field clone_type hardlink ; # Type of clone to construct
+field readtree_err        ; # Error output from read-tree (if any)
+
+constructor pick {} {
+	global M1T M1B
+
+	make_toplevel top w
+	wm title $top [mc "Git Gui"]
+
+	if {$top eq {.}} {
+		menu $w.mbar -tearoff 0
+		$top configure -menu $w.mbar
+
+		$w.mbar add cascade \
+			-label [mc Repository] \
+			-menu $w.mbar.repository
+		menu $w.mbar.repository
+		$w.mbar.repository add command \
+			-label [mc Quit] \
+			-command exit \
+			-accelerator $M1T-Q
+
+		if {[is_MacOSX]} {
+			$w.mbar add cascade -label [mc Apple] -menu .mbar.apple
+			menu $w.mbar.apple
+			$w.mbar.apple add command \
+				-label [mc "About %s" [appname]] \
+				-command do_about
+		} else {
+			$w.mbar add cascade -label [mc Help] -menu $w.mbar.help
+			menu $w.mbar.help
+			$w.mbar.help add command \
+				-label [mc "About %s" [appname]] \
+				-command do_about
+		}
+
+		_center $top 500 350
+		wm protocol $top WM_DELETE_WINDOW exit
+		bind $top <$M1B-q> exit
+		bind $top <$M1B-Q> exit
+		bind $top <Key-Escape> exit
+	} else {
+		wm geometry $top "+[winfo rootx .]+[winfo rooty .]"
+		bind $top <Key-Escape> [list destroy $top]
+	}
+
+	label $w.git_logo \
+		-borderwidth 1 \
+		-relief sunken \
+		-background white \
+		-image ::choose_repository::git_logo
+	pack $w.git_logo -side top -fill x -padx 20 -pady 20
+
+	set w_body $w.body
+	frame $w_body
+	radiobutton $w_body.new \
+		-anchor w \
+		-text [mc "Create New Repository"] \
+		-variable @action \
+		-value new
+	radiobutton $w_body.clone \
+		-anchor w \
+		-text [mc "Clone Existing Repository"] \
+		-variable @action \
+		-value clone
+	radiobutton $w_body.open \
+		-anchor w \
+		-text [mc "Open Existing Repository"] \
+		-variable @action \
+		-value open
+	pack $w_body.new -anchor w -fill x
+	pack $w_body.clone -anchor w -fill x
+	pack $w_body.open -anchor w -fill x
+	pack $w_body -fill x -padx 10
+
+	frame $w.buttons
+	set w_next $w.buttons.next
+	button $w_next \
+		-default active \
+		-text [mc "Next >"] \
+		-command [cb _next]
+	pack $w_next -side right -padx 5
+	button $w.buttons.quit \
+		-text [mc "Quit"] \
+		-command exit
+	pack $w.buttons.quit -side right -padx 5
+	pack $w.buttons -side bottom -fill x -padx 10 -pady 10
+
+	bind $top <Return> [cb _invoke_next]
+	bind $top <Visibility> "
+		grab $top
+		focus $top
+	"
+	tkwait variable @done
+
+	if {$top eq {.}} {
+		eval destroy [winfo children $top]
+		_center $top 500 600
+	}
+}
+
+proc _home {} {
+	if {[catch {set h $::env(HOME)}]
+		|| ![file isdirectory $h]} {
+		set h .
+	}
+	return $h
+}
+
+proc _center {top nx ny} {
+	set rx [expr {([winfo screenwidth  $top] - $nx) / 2}]
+	set ry [expr {([winfo screenheight $top] - $ny) / 2}]
+	wm geometry $top [format {%dx%d+%d+%d} $nx $ny $rx $ry]
+}
+
+method _invoke_next {} {
+	if {[winfo exists $w_next]} {
+		uplevel #0 [$w_next cget -command]
+	}
+}
+
+method _next {} {
+	destroy $w_body
+	_do_$action $this
+}
+
+method _write_local_path {args} {
+	if {$local_path eq {}} {
+		$w_next conf -state disabled
+	} else {
+		$w_next conf -state normal
+	}
+}
+
+method _git_init {} {
+	if {[file exists $local_path]} {
+		error_popup [mc "Location %s already exists." $local_path]
+		return 0
+	}
+
+	if {[catch {file mkdir $local_path} err]} {
+		error_popup [strcat \
+			[mc "Failed to create repository %s:" $local_path] \
+			"\n\n$err"]
+		return 0
+	}
+
+	if {[catch {cd $local_path} err]} {
+		error_popup [strcat \
+			[mc "Failed to create repository %s:" $local_path] \
+			"\n\n$err"]
+		return 0
+	}
+
+	if {[catch {git init} err]} {
+		error_popup [strcat \
+			[mc "Failed to create repository %s:" $local_path] \
+			"\n\n$err"]
+		return 0
+	}
+
+	set ::_gitdir .git
+	set ::_prefix {}
+	return 1
+}
+
+proc _is_git {path} {
+	if {[file exists [file join $path HEAD]]
+	 && [file exists [file join $path objects]]
+	 && [file exists [file join $path config]]} {
+		return 1
+	}
+	return 0
+}
+
+######################################################################
+##
+## Create New Repository
+
+method _do_new {} {
+	$w_next conf \
+		-state disabled \
+		-command [cb _do_new2] \
+		-text [mc "Create"]
+
+	frame $w_body
+	label $w_body.h \
+		-font font_uibold \
+		-text [mc "Create New Repository"]
+	pack $w_body.h -side top -fill x -pady 10
+	pack $w_body -fill x -padx 10
+
+	frame $w_body.where
+	label $w_body.where.l -text [mc "Directory:"]
+	entry $w_body.where.t \
+		-textvariable @local_path \
+		-font font_diff \
+		-width 50
+	button $w_body.where.b \
+		-text [mc "Browse"] \
+		-command [cb _new_local_path]
+
+	pack $w_body.where.b -side right
+	pack $w_body.where.l -side left
+	pack $w_body.where.t -fill x
+	pack $w_body.where -fill x
+
+	trace add variable @local_path write [cb _write_local_path]
+	update
+	focus $w_body.where.t
+}
+
+method _new_local_path {} {
+	if {$local_path ne {}} {
+		set p [file dirname $local_path]
+	} else {
+		set p [_home]
+	}
+
+	set p [tk_chooseDirectory \
+		-initialdir $p \
+		-parent $top \
+		-title [mc "Git Repository"] \
+		-mustexist false]
+	if {$p eq {}} return
+
+	set p [file normalize $p]
+	if {[file isdirectory $p]} {
+		foreach i [glob \
+			-directory $p \
+			-tails \
+			-nocomplain \
+			* .*] {
+			switch -- $i {
+			 . continue
+			.. continue
+			default {
+				error_popup [mc "Directory %s already exists." $p]
+				return
+			}
+			}
+		}
+		if {[catch {file delete $p} err]} {
+			error_popup [strcat \
+				[mc "Directory %s already exists." $p] \
+				"\n\n$err"]
+			return
+		}
+	} elseif {[file exists $p]} {
+		error_popup [mc "File %s already exists." $p]
+		return
+	}
+	set local_path $p
+}
+
+method _do_new2 {} {
+	if {![_git_init $this]} {
+		return
+	}
+	set done 1
+}
+
+######################################################################
+##
+## Clone Existing Repository
+
+method _do_clone {} {
+	$w_next conf \
+		-state disabled \
+		-command [cb _do_clone2] \
+		-text [mc "Clone"]
+
+	frame $w_body
+	label $w_body.h \
+		-font font_uibold \
+		-text [mc "Clone Existing Repository"]
+	pack $w_body.h -side top -fill x -pady 10
+	pack $w_body -fill x -padx 10
+
+	set args $w_body.args
+	frame $w_body.args
+	pack $args -fill both
+
+	label $args.origin_l -text [mc "URL:"]
+	entry $args.origin_t \
+		-textvariable @origin_url \
+		-font font_diff \
+		-width 50
+	button $args.origin_b \
+		-text [mc "Browse"] \
+		-command [cb _open_origin]
+	grid $args.origin_l $args.origin_t $args.origin_b -sticky ew
+
+	label $args.where_l -text [mc "Directory:"]
+	entry $args.where_t \
+		-textvariable @local_path \
+		-font font_diff \
+		-width 50
+	button $args.where_b \
+		-text [mc "Browse"] \
+		-command [cb _new_local_path]
+	grid $args.where_l $args.where_t $args.where_b -sticky ew
+
+	label $args.type_l -text [mc "Clone Type:"]
+	frame $args.type_f
+	set w_types [list]
+	lappend w_types [radiobutton $args.type_f.hardlink \
+		-state disabled \
+		-anchor w \
+		-text [mc "Standard (Fast, Semi-Redundant, Hardlinks)"] \
+		-variable @clone_type \
+		-value hardlink]
+	lappend w_types [radiobutton $args.type_f.full \
+		-state disabled \
+		-anchor w \
+		-text [mc "Full Copy (Slower, Redundant Backup)"] \
+		-variable @clone_type \
+		-value full]
+	lappend w_types [radiobutton $args.type_f.shared \
+		-state disabled \
+		-anchor w \
+		-text [mc "Shared (Fastest, Not Recommended, No Backup)"] \
+		-variable @clone_type \
+		-value shared]
+	foreach r $w_types {
+		pack $r -anchor w
+	}
+	grid $args.type_l $args.type_f -sticky new
+
+	grid columnconfigure $args 1 -weight 1
+
+	trace add variable @local_path write [cb _update_clone]
+	trace add variable @origin_url write [cb _update_clone]
+	update
+	focus $args.origin_t
+}
+
+method _open_origin {} {
+	if {$origin_url ne {} && [file isdirectory $origin_url]} {
+		set p $origin_url
+	} else {
+		set p [_home]
+	}
+
+	set p [tk_chooseDirectory \
+		-initialdir $p \
+		-parent $top \
+		-title [mc "Git Repository"] \
+		-mustexist true]
+	if {$p eq {}} return
+
+	set p [file normalize $p]
+	if {![_is_git [file join $p .git]] && ![_is_git $p]} {
+		error_popup [mc "Not a Git repository: %s" [file tail $p]]
+		return
+	}
+	set origin_url $p
+}
+
+method _update_clone {args} {
+	if {$local_path ne {} && $origin_url ne {}} {
+		$w_next conf -state normal
+	} else {
+		$w_next conf -state disabled
+	}
+
+	if {$origin_url ne {} &&
+		(  [_is_git [file join $origin_url .git]]
+		|| [_is_git $origin_url])} {
+		set e normal
+		if {[[lindex $w_types 0] cget -state] eq {disabled}} {
+			set clone_type hardlink
+		}
+	} else {
+		set e disabled
+		set clone_type full
+	}
+
+	foreach r $w_types {
+		$r conf -state $e
+	}
+}
+
+method _do_clone2 {} {
+	if {[file isdirectory $origin_url]} {
+		set origin_url [file normalize $origin_url]
+	}
+
+	if {$clone_type eq {hardlink} && ![file isdirectory $origin_url]} {
+		error_popup [mc "Standard only available for local repository."]
+		return
+	}
+	if {$clone_type eq {shared} && ![file isdirectory $origin_url]} {
+		error_popup [mc "Shared only available for local repository."]
+		return
+	}
+
+	if {$clone_type eq {hardlink} || $clone_type eq {shared}} {
+		set objdir [file join $origin_url .git objects]
+		if {![file isdirectory $objdir]} {
+			set objdir [file join $origin_url objects]
+			if {![file isdirectory $objdir]} {
+				error_popup [mc "Not a Git repository: %s" [file tail $origin_url]]
+				return
+			}
+		}
+	}
+
+	set giturl $origin_url
+	if {[is_Cygwin] && [file isdirectory $giturl]} {
+		set giturl [exec cygpath --unix --absolute $giturl]
+		if {$clone_type eq {shared}} {
+			set objdir [exec cygpath --unix --absolute $objdir]
+		}
+	}
+
+	if {![_git_init $this]} return
+	set local_path [pwd]
+
+	if {[catch {
+			git config remote.$origin_name.url $giturl
+			git config remote.$origin_name.fetch +refs/heads/*:refs/remotes/$origin_name/*
+		} err]} {
+		error_popup [strcat [mc "Failed to configure origin"] "\n\n$err"]
+		return
+	}
+
+	destroy $w_body $w_next
+
+	switch -exact -- $clone_type {
+	hardlink {
+		set tolink  [list]
+		file mkdir [file join .git objects pack]
+		foreach i [glob -tails -nocomplain \
+			-directory [file join $objdir pack] *] {
+			lappend tolink [file join pack $i]
+		}
+		foreach i [glob -tails -nocomplain \
+			-directory [file join $objdir] ??] {
+			file mkdir [file join .git objects $i]
+			foreach j [glob -tails -nocomplain \
+				-directory [file join $objdir $i] *] {
+				lappend tolink [file join $i $j]
+			}
+		}
+
+		if {$tolink eq {}} {
+			info_popup [strcat \
+				[mc "Nothing to clone from %s." $origin_url] \
+				"\n" \
+				[mc "The 'master' branch has not been initialized."] \
+				]
+			set done 1
+			return
+		}
+
+		set o_cons [status_bar::new $w_body]
+		pack $w_body -fill x -padx 10
+
+		set i [lindex $tolink 0]
+		if {[catch {
+				file link -hard \
+					[file join .git objects $i] \
+					[file join $objdir $i]
+			} err]} {
+			info_popup [strcat \
+				[mc "Hardlinks are unavailable.  Falling back to copying."] \
+				"\n" \
+				$err]
+			set i [_copy_files $this $objdir $tolink]
+		} else {
+			set i [_link_files $this $objdir [lrange $tolink 1 end]]
+		}
+		if {!$i} return
+
+		destroy $w_body
+	}
+	full {
+		set o_cons [console::embed \
+			$w_body \
+			[mc "Cloning from %s" $origin_url]]
+		pack $w_body -fill both -expand 1 -padx 10
+		$o_cons exec \
+			[list git fetch --no-tags -k $origin_name] \
+			[cb _do_clone_tags]
+	}
+	shared {
+		set fd [open [gitdir objects info alternates] w]
+		fconfigure $fd -translation binary
+		puts $fd $objdir
+		close $fd
+	}
+	}
+
+	if {$clone_type eq {hardlink} || $clone_type eq {shared}} {
+		if {![_clone_refs $this]} return
+		set pwd [pwd]
+		if {[catch {
+				cd $origin_url
+				set HEAD [git rev-parse --verify HEAD^0]
+			} err]} {
+			_clone_failed $this [mc "Not a Git repository: %s" [file tail $origin_url]]
+			return 0
+		}
+		cd $pwd
+		_do_clone_checkout $this $HEAD
+	}
+}
+
+method _copy_files {objdir tocopy} {
+	$o_cons start \
+		[mc "Copying objects"] \
+		[mc "KiB"]
+	set tot 0
+	set cmp 0
+	foreach p $tocopy {
+		incr tot [file size [file join $objdir $p]]
+	}
+	foreach p $tocopy {
+		if {[catch {
+				set f_in [open [file join $objdir $p] r]
+				set f_cp [open [file join .git objects $p] w]
+				fconfigure $f_in -translation binary -encoding binary
+				fconfigure $f_cp -translation binary -encoding binary
+
+				while {![eof $f_in]} {
+					incr cmp [fcopy $f_in $f_cp -size 16384]
+					$o_cons update \
+						[expr {$cmp / 1024}] \
+						[expr {$tot / 1024}]
+					update
+				}
+
+				close $f_in
+				close $f_cp
+			} err]} {
+			_clone_failed $this [mc "Unable to copy object: %s" $err]
+			return 0
+		}
+	}
+	return 1
+}
+
+method _link_files {objdir tolink} {
+	set total [llength $tolink]
+	$o_cons start \
+		[mc "Linking objects"] \
+		[mc "objects"]
+	for {set i 0} {$i < $total} {} {
+		set p [lindex $tolink $i]
+		if {[catch {
+				file link -hard \
+					[file join .git objects $p] \
+					[file join $objdir $p]
+			} err]} {
+			_clone_failed $this [mc "Unable to hardlink object: %s" $err]
+			return 0
+		}
+
+		incr i
+		if {$i % 5 == 0} {
+			$o_cons update $i $total
+			update
+		}
+	}
+	return 1
+}
+
+method _clone_refs {} {
+	set pwd [pwd]
+	if {[catch {cd $origin_url} err]} {
+		error_popup [mc "Not a Git repository: %s" [file tail $origin_url]]
+		return 0
+	}
+	set fd_in [git_read for-each-ref \
+		--tcl \
+		{--format=list %(refname) %(objectname) %(*objectname)}]
+	cd $pwd
+
+	set fd [open [gitdir packed-refs] w]
+	fconfigure $fd -translation binary
+	puts $fd "# pack-refs with: peeled"
+	while {[gets $fd_in line] >= 0} {
+		set line [eval $line]
+		set refn [lindex $line 0]
+		set robj [lindex $line 1]
+		set tobj [lindex $line 2]
+
+		if {[regsub ^refs/heads/ $refn \
+			"refs/remotes/$origin_name/" refn]} {
+			puts $fd "$robj $refn"
+		} elseif {[string match refs/tags/* $refn]} {
+			puts $fd "$robj $refn"
+			if {$tobj ne {}} {
+				puts $fd "^$tobj"
+			}
+		}
+	}
+	close $fd_in
+	close $fd
+	return 1
+}
+
+method _do_clone_tags {ok} {
+	if {$ok} {
+		$o_cons exec \
+			[list git fetch --tags -k $origin_name] \
+			[cb _do_clone_HEAD]
+	} else {
+		$o_cons done $ok
+		_clone_failed $this [mc "Cannot fetch branches and objects.  See console output for details."]
+	}
+}
+
+method _do_clone_HEAD {ok} {
+	if {$ok} {
+		$o_cons exec \
+			[list git fetch $origin_name HEAD] \
+			[cb _do_clone_full_end]
+	} else {
+		$o_cons done $ok
+		_clone_failed $this [mc "Cannot fetch tags.  See console output for details."]
+	}
+}
+
+method _do_clone_full_end {ok} {
+	$o_cons done $ok
+
+	if {$ok} {
+		destroy $w_body
+
+		set HEAD {}
+		if {[file exists [gitdir FETCH_HEAD]]} {
+			set fd [open [gitdir FETCH_HEAD] r]
+			while {[gets $fd line] >= 0} {
+				if {[regexp "^(.{40})\t\t" $line line HEAD]} {
+					break
+				}
+			}
+			close $fd
+		}
+
+		catch {git pack-refs}
+		_do_clone_checkout $this $HEAD
+	} else {
+		_clone_failed $this [mc "Cannot determine HEAD.  See console output for details."]
+	}
+}
+
+method _clone_failed {{why {}}} {
+	if {[catch {file delete -force $local_path} err]} {
+		set why [strcat \
+			$why \
+			"\n\n" \
+			[mc "Unable to cleanup %s" $local_path] \
+			"\n\n" \
+			$err]
+	}
+	if {$why ne {}} {
+		update
+		error_popup [strcat [mc "Clone failed."] "\n" $why]
+	}
+}
+
+method _do_clone_checkout {HEAD} {
+	if {$HEAD eq {}} {
+		info_popup [strcat \
+			[mc "No default branch obtained."] \
+			"\n" \
+			[mc "The 'master' branch has not been initialized."] \
+			]
+		set done 1
+		return
+	}
+	if {[catch {
+			git update-ref HEAD $HEAD^0
+		} err]} {
+		info_popup [strcat \
+			[mc "Cannot resolve %s as a commit." $HEAD^0] \
+			"\n  $err" \
+			"\n" \
+			[mc "The 'master' branch has not been initialized."] \
+			]
+		set done 1
+		return
+	}
+
+	set o_cons [status_bar::new $w_body]
+	pack $w_body -fill x -padx 10
+	$o_cons start \
+		[mc "Creating working directory"] \
+		[mc "files"]
+
+	set readtree_err {}
+	set fd [git_read --stderr read-tree \
+		-m \
+		-u \
+		-v \
+		HEAD \
+		HEAD \
+		]
+	fconfigure $fd -blocking 0 -translation binary
+	fileevent $fd readable [cb _readtree_wait $fd]
+}
+
+method _readtree_wait {fd} {
+	set buf [read $fd]
+	$o_cons update_meter $buf
+	append readtree_err $buf
+
+	fconfigure $fd -blocking 1
+	if {![eof $fd]} {
+		fconfigure $fd -blocking 0
+		return
+	}
+
+	if {[catch {close $fd}]} {
+		set err $readtree_err
+		regsub {^fatal: } $err {} err
+		error_popup [strcat \
+			[mc "Initial file checkout failed."] \
+			"\n\n$err"]
+		return
+	}
+
+	set done 1
+}
+
+######################################################################
+##
+## Open Existing Repository
+
+method _do_open {} {
+	$w_next conf \
+		-state disabled \
+		-command [cb _do_open2] \
+		-text [mc "Open"]
+
+	frame $w_body
+	label $w_body.h \
+		-font font_uibold \
+		-text [mc "Open Existing Repository"]
+	pack $w_body.h -side top -fill x -pady 10
+	pack $w_body -fill x -padx 10
+
+	frame $w_body.where
+	label $w_body.where.l -text [mc "Repository:"]
+	entry $w_body.where.t \
+		-textvariable @local_path \
+		-font font_diff \
+		-width 50
+	button $w_body.where.b \
+		-text [mc "Browse"] \
+		-command [cb _open_local_path]
+
+	pack $w_body.where.b -side right
+	pack $w_body.where.l -side left
+	pack $w_body.where.t -fill x
+	pack $w_body.where -fill x
+
+	trace add variable @local_path write [cb _write_local_path]
+	update
+	focus $w_body.where.t
+}
+
+method _open_local_path {} {
+	if {$local_path ne {}} {
+		set p $local_path
+	} else {
+		set p [_home]
+	}
+
+	set p [tk_chooseDirectory \
+		-initialdir $p \
+		-parent $top \
+		-title [mc "Git Repository"] \
+		-mustexist true]
+	if {$p eq {}} return
+
+	set p [file normalize $p]
+	if {![_is_git [file join $p .git]]} {
+		error_popup [mc "Not a Git repository: %s" [file tail $p]]
+		return
+	}
+	set local_path $p
+}
+
+method _do_open2 {} {
+	if {![_is_git [file join $local_path .git]]} {
+		error_popup [mc "Not a Git repository: %s" [file tail $local_path]]
+		return
+	}
+
+	if {[catch {cd $local_path} err]} {
+		error_popup [strcat \
+			[mc "Failed to open repository %s:" $local_path] \
+			"\n\n$err"]
+		return
+	}
+
+	set ::_gitdir .git
+	set ::_prefix {}
+	set done 1
+}
+
+}