units: add systemd-debug-shell.service

If enabled, the service provides a root shell from an early boot. It also
remains active late into shutdown. It is useful for debugging startup and
shutdown problems.

This is the unit referenced in
http://freedesktop.org/wiki/Software/systemd/Debugging#early_debug_shell

Makefile.am

@@ -340,7 +340,8 @@ nodist_systemunit_DATA = \
 	units/user@.service \
 	units/systemd-udev.service \
 	units/systemd-udev-trigger.service \
-	units/systemd-udev-settle.service
+	units/systemd-udev-settle.service \
+	units/systemd-debug-shell.service
 
 dist_userunit_DATA = \
 	units/user/default.target \
@@ -378,6 +379,7 @@ EXTRA_DIST += \
 	units/systemd-udev.service \
 	units/systemd-udev-trigger.service \
 	units/systemd-udev-settle.service \
+	units/systemd-debug-shell.service.in \
 	units/hibernate.service.in \
 	units/suspend.service.in \
 	introspect.awk \
@@ -3019,6 +3021,7 @@ SED_PROCESS = \
 		-e 's,@VERSION\@,$(VERSION),g' \
 		-e 's,@rootprefix\@,$(rootprefix),g' \
 		-e 's,@udevlibexecdir\@,$(libexecdir)/udev,g' \
+		-e 's,@sushell\@,$(sushell),g' \
 		< $< > $@ || rm $@
 
 units/%: units/%.in Makefile

configure.ac

@@ -172,6 +172,12 @@ if test "x$enable_selinux" != "xno"; then
         fi
 fi
 AM_CONDITIONAL(HAVE_SELINUX, [test "$have_selinux" = "yes"])
+if test "x${have_selinux}" != xno ; then
+        sushell=/sbin/sushell
+else
+        sushell=/bin/bash
+fi
+AC_SUBST(sushell)
 
 # ------------------------------------------------------------------------------
 have_xz=no

units/systemd-debug-shell.service.in

@@ -0,0 +1,25 @@
+[Unit]
+Description=Early root shell on tty9 FOR DEBUGGING ONLY
+DefaultDependencies=no
+IgnoreOnIsolate=yes
+
+[Service]
+Environment=TERM=linux
+ExecStart=@sushell@
+Restart=always
+RestartSec=0
+StandardInput=tty
+TTYPath=/dev/tty9
+TTYReset=yes
+TTYVHangup=yes
+KillMode=process
+IgnoreSIGPIPE=no
+# bash ignores SIGTERM
+KillSignal=SIGHUP
+
+# Unset locale for the console getty since the console has problems
+# displaying some internationalized messages.
+Environment=LANG= LANGUAGE= LC_CTYPE= LC_NUMERIC= LC_TIME= LC_COLLATE= LC_MONETARY= LC_MESSAGES= LC_PAPER= LC_NAME= LC_ADDRESS= LC_TELEPHONE= LC_MEASUREMENT= LC_IDENTIFICATION=
+
+[Install]
+WantedBy=sysinit.target