git-gui: Add a dialog that shows the OpenSSH public key.

Generating a new SSH key or finding an existing one may
be a difficult task for non-technical users, especially
on Windows.

This commit adds a new dialog that shows the public key,
or allows the user to generate a new one if none were found.
Since this is a convenience/informational feature for new
users, and the dialog is mostly read-only, it is located
in the Help menu.

The command line used to invoke ssh-keygen is designed to
force it to use SSH_ASKPASS if available, or accept empty
passphrases, but _never_ wait for user response on the tty.

Signed-off-by: Alexander Gavrilov <angavrilov@gmail.com>
Acked-by: Johannes Sixt <johannes.sixt@telecom.at>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

git-gui.sh

@@ -2536,6 +2536,10 @@ proc start_browser {url} {
 
 .mbar.help add command -label [mc "Online Documentation"] \
 	-command [list start_browser $doc_url]
+
+.mbar.help add command -label [mc "Show SSH Key"] \
+	-command do_ssh_key
+
 unset doc_path doc_url
 
 # -- Standard bindings

lib/sshkey.tcl

@@ -0,0 +1,126 @@
+# git-gui about git-gui dialog
+# Copyright (C) 2006, 2007 Shawn Pearce
+
+proc find_ssh_key {} {
+	foreach name {~/.ssh/id_dsa.pub ~/.ssh/id_rsa.pub ~/.ssh/identity.pub} {
+		if {[file exists $name]} {
+			set fh    [open $name r]
+			set cont  [read $fh]
+			close $fh
+			return [list $name $cont]
+		}
+	}
+
+	return {}
+}
+
+proc do_ssh_key {} {
+	global sshkey_title have_tk85 sshkey_fd
+
+	set w .sshkey_dialog
+	if {[winfo exists $w]} {
+		raise $w
+		return
+	}
+
+	toplevel $w
+	wm transient $w .
+
+	set finfo [find_ssh_key]
+	if {$finfo eq {}} {
+		set sshkey_title [mc "No keys found."]
+		set gen_state   normal
+	} else {
+		set sshkey_title [mc "Found a public key in: %s" [lindex $finfo 0]]
+		set gen_state   disabled
+	}
+
+	frame $w.header -relief flat
+	label $w.header.lbl -textvariable sshkey_title -anchor w
+	button $w.header.gen -text [mc "Generate Key"] \
+		-command [list make_ssh_key $w] -state $gen_state
+	pack $w.header.lbl -side left -expand 1 -fill x
+	pack $w.header.gen -side right
+	pack $w.header -fill x -pady 5 -padx 5
+
+	text $w.contents -width 60 -height 10 -wrap char -relief sunken
+	pack $w.contents -fill both -expand 1
+	if {$have_tk85} {
+		$w.contents configure -inactiveselectbackground darkblue
+	}
+
+	frame $w.buttons
+	button $w.buttons.close -text [mc Close] \
+		-default active -command [list destroy $w]
+	pack $w.buttons.close -side right
+	button $w.buttons.copy -text [mc "Copy To Clipboard"] \
+		-command [list tk_textCopy $w.contents]
+	pack $w.buttons.copy -side left
+	pack $w.buttons -side bottom -fill x -pady 5 -padx 5
+
+	if {$finfo ne {}} {
+		$w.contents insert end [lindex $finfo 1] sel
+	}
+	$w.contents configure -state disabled
+
+	bind $w <Visibility> "grab $w; focus $w.buttons.close"
+	bind $w <Key-Escape> "destroy $w"
+	bind $w <Key-Return> "destroy $w"
+	bind $w <Destroy> kill_sshkey
+	wm title $w [mc "Your OpenSSH Public Key"]
+	tk::PlaceWindow $w widget .
+	tkwait window $w
+}
+
+proc make_ssh_key {w} {
+	global sshkey_title sshkey_output sshkey_fd
+
+	set sshkey_title [mc "Generating..."]
+	$w.header.gen configure -state disabled
+
+	set cmdline [list sh -c {echo | ssh-keygen -q -t rsa -f ~/.ssh/id_rsa 2>&1}]
+
+	if {[catch { set sshkey_fd [_open_stdout_stderr $cmdline] } err]} {
+		error_popup [mc "Could not start ssh-keygen:\n\n%s" $err]
+		return
+	}
+
+	set sshkey_output {}
+	fconfigure $sshkey_fd -blocking 0
+	fileevent $sshkey_fd readable [list read_sshkey_output $sshkey_fd $w]
+}
+
+proc kill_sshkey {} {
+	global sshkey_fd
+	if {![info exists sshkey_fd]} return
+	catch { kill_file_process $sshkey_fd }
+	catch { close $sshkey_fd }
+}
+
+proc read_sshkey_output {fd w} {
+	global sshkey_fd sshkey_output sshkey_title
+
+	set sshkey_output "$sshkey_output[read $fd]"
+	if {![eof $fd]} return
+
+	fconfigure $fd -blocking 1
+	unset sshkey_fd
+
+	$w.contents configure -state normal
+	if {[catch {close $fd} err]} {
+		set sshkey_title [mc "Generation failed."]
+		$w.contents insert end $err
+		$w.contents insert end "\n"
+		$w.contents insert end $sshkey_output
+	} else {
+		set finfo [find_ssh_key]
+		if {$finfo eq {}} {
+			set sshkey_title [mc "Generation succeded, but no keys found."]
+			$w.contents insert end $sshkey_output
+		} else {
+			set sshkey_title [mc "Your key is in: %s" [lindex $finfo 0]]
+			$w.contents insert end [lindex $finfo 1] sel
+		}
+	}
+	$w.contents configure -state disable
+}