git-gui: Add a simple implementation of SSH_ASKPASS.

OpenSSH allows specifying an external program to use
for direct user interaction. While most Linux systems
already have such programs, some environments, for
instance, msysgit, lack it. This patch adds a simple
fallback Tcl implementation of the tool.

In msysgit it is also necessary to set a fake value of
the DISPLAY variable, because otherwise ssh won't even
try to use SSH_ASKPASS handlers.

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>

3 files changed, 73 insertions, 0 deletions

diff --git a/Makefile b/Makefile
index 55765c8a3a..3ad8a21b30 100644
--- a/Makefile
+++ b/Makefile
@@ -285,6 +285,7 @@ all:: $(GITGUI_MAIN) lib/tclIndex $(ALL_MSGFILES)
 install: all
 	$(QUIET)$(INSTALL_D0)'$(DESTDIR_SQ)$(gitexecdir_SQ)' $(INSTALL_D1)
 	$(QUIET)$(INSTALL_X0)git-gui $(INSTALL_X1) '$(DESTDIR_SQ)$(gitexecdir_SQ)'
+	$(QUIET)$(INSTALL_X0)git-gui--askpass $(INSTALL_X1) '$(DESTDIR_SQ)$(gitexecdir_SQ)'
 	$(QUIET)$(foreach p,$(GITGUI_BUILT_INS), $(INSTALL_L0)'$(DESTDIR_SQ)$(gitexecdir_SQ)/$p' $(INSTALL_L1)'$(DESTDIR_SQ)$(gitexecdir_SQ)/git-gui' $(INSTALL_L2)'$(DESTDIR_SQ)$(gitexecdir_SQ)/$p' $(INSTALL_L3) &&) true
 ifdef GITGUI_WINDOWS_WRAPPER
 	$(QUIET)$(INSTALL_R0)git-gui.tcl $(INSTALL_R1) '$(DESTDIR_SQ)$(gitexecdir_SQ)'
@@ -302,6 +303,7 @@ endif
 uninstall:
 	$(QUIET)$(CLEAN_DST) '$(DESTDIR_SQ)$(gitexecdir_SQ)'
 	$(QUIET)$(REMOVE_F0)'$(DESTDIR_SQ)$(gitexecdir_SQ)'/git-gui $(REMOVE_F1)
+	$(QUIET)$(REMOVE_F0)'$(DESTDIR_SQ)$(gitexecdir_SQ)'/git-gui--askpass $(REMOVE_F1)
 	$(QUIET)$(foreach p,$(GITGUI_BUILT_INS), $(REMOVE_F0)'$(DESTDIR_SQ)$(gitexecdir_SQ)'/$p $(REMOVE_F1) &&) true
 ifdef GITGUI_WINDOWS_WRAPPER
 	$(QUIET)$(REMOVE_F0)'$(DESTDIR_SQ)$(gitexecdir_SQ)'/git-gui.tcl $(REMOVE_F1)
diff --git a/git-gui--askpass b/git-gui--askpass
new file mode 100755
index 0000000000..12e117ecb1
--- /dev/null
+++ b/git-gui--askpass
@@ -0,0 +1,59 @@
+#!/bin/sh
+# Tcl ignores the next line -*- tcl -*- \
+exec wish "$0" -- "$@"
+
+# This is a trivial implementation of an SSH_ASKPASS handler.
+# Git-gui uses this script if none are already configured.
+
+set answer {}
+set yesno  0
+set rc     255
+
+if {$argc < 1} {
+	set prompt "Enter your OpenSSH passphrase:"
+} else {
+	set prompt [join $argv " "]
+	if {[regexp -nocase {\(yes\/no\)\?\s*$} $prompt]} {
+		set yesno 1
+	}
+}
+
+message .m -text $prompt -justify center -aspect 4000
+pack .m -side top -fill x -padx 20 -pady 20 -expand 1
+
+entry .e -textvariable answer -width 50
+pack .e -side top -fill x -padx 10 -pady 10
+
+if {!$yesno} {
+	.e configure -show "*"
+}
+
+frame .b
+button .b.ok     -text OK     -command finish
+button .b.cancel -text Cancel -command {destroy .}
+
+pack .b.ok -side left -expand 1
+pack .b.cancel -side right -expand 1
+pack .b -side bottom -fill x -padx 10 -pady 10
+
+bind . <Visibility> {focus -force .e}
+bind . <Key-Return> finish
+bind . <Key-Escape> {destroy .}
+bind . <Destroy>    {exit $rc}
+
+proc finish {} {
+	if {$::yesno} {
+		if {$::answer ne "yes" && $::answer ne "no"} {
+			tk_messageBox -icon error -title "Error" -type ok \
+				-message "Only 'yes' or 'no' input allowed."
+			return
+		}
+	}
+
+	set ::rc 0
+	puts $::answer
+	destroy .
+}
+
+wm title . "OpenSSH"
+tk::PlaceWindow .
diff --git a/git-gui.sh b/git-gui.sh
index e4d1f70f1c..12b496bec9 100755
--- a/git-gui.sh
+++ b/git-gui.sh
@@ -592,6 +592,11 @@ bind . <Visibility> {
 if {[is_Windows]} {
 	wm iconbitmap . -default $oguilib/git-gui.ico
 	set ::tk::AlwaysShowSelection 1
+
+	# Spoof an X11 display for SSH
+	if {![info exists env(DISPLAY)]} {
+		set env(DISPLAY) :9999
+	}
 }
 
 ######################################################################
@@ -1071,6 +1076,13 @@ set nullid2 "0000000000000000000000000000000000000001"
 set have_tk85 [expr {[package vcompare $tk_version "8.5"] >= 0}]
 
 ######################################################################
+
+# Suggest our implementation of askpass, if none is set
+if {![info exists env(SSH_ASKPASS)]} {
+	set env(SSH_ASKPASS) [gitexec git-gui--askpass]
+}
+
+######################################################################
 ##
 ## task management