tools/xenstore: add live update command to xenstore-control

Add the "live-update" command to xenstore-control enabling updating
xenstored to a new version in a running Xen system.

With -c <arg> it is possible to pass a different command line to the
new instance of xenstored. This will replace the command line used
for the invocation of the just running xenstored instance.

The running xenstored (or xenstore-stubdom) needs to support live
updating, of course.

For now just add a small dummy handler to C xenstore denying any
live update action.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Paul Durrant <paul@xen.org>
Reviewed-by: Julien Grall <jgrall@amazon.com>
Acked-by: Wei Liu <wl@xen.org>

docs/misc/xenstore.txt

@@ -317,6 +317,27 @@ CONTROL			<command>|[<parameters>|]
 	Current commands are:
 	check
 		checks xenstored innards
+	live-update|<params>|+
+		perform a live-update of the Xenstore daemon, only to
+		be used via xenstore-control command.
+		<params> are implementation specific and are used for
+		different steps of the live-update processing. Currently
+		supported <params> are:
+		-f <file>  specify new daemon binary
+		-b <size>  specify size of new stubdom binary
+		-d <chunk-size> <binary-chunk>  transfer chunk of new
+			stubdom binary
+		-c <pars>  specify new command line to use
+		-s [-t <sec>] [-F]  start live update process (-t specifies
+			timeout in seconds to wait for active transactions
+			to finish, default is 60 seconds; -F will force
+			live update to happen even with running transactions
+			after timeout elapsed)
+		-a  abort live update handling
+		All sub-options will return "OK" in case of success or an
+		error string in case of failure. -s can return "BUSY" in case
+		of an active transaction, a retry of -s can be done in that
+		case.
 	log|on
 		turn xenstore logging on
 	log|off

tools/xenstore/Makefile

@@ -11,6 +11,7 @@ CFLAGS += -include $(XEN_ROOT)/tools/config.h
 CFLAGS += -I./include
 CFLAGS += $(CFLAGS_libxenevtchn)
 CFLAGS += $(CFLAGS_libxenctrl)
+CFLAGS += $(CFLAGS_libxenguest)
 CFLAGS += $(CFLAGS_libxentoolcore)
 CFLAGS += -DXEN_LIB_STORED="\"$(XEN_LIB_STORED)\""
 CFLAGS += -DXEN_RUN_STORED="\"$(XEN_RUN_STORED)\""
@@ -81,7 +82,7 @@ xenstore: xenstore_client.o
 	$(CC) $< $(LDFLAGS) $(LDLIBS_libxenstore) $(LDLIBS_libxentoolcore) $(SOCKET_LIBS) -o $@ $(APPEND_LDFLAGS)
 
 xenstore-control: xenstore_control.o
-	$(CC) $< $(LDFLAGS) $(LDLIBS_libxenstore) $(LDLIBS_libxentoolcore) $(SOCKET_LIBS) -o $@ $(APPEND_LDFLAGS)
+	$(CC) $< $(LDFLAGS) $(LDLIBS_libxenstore) $(LDLIBS_libxenctrl) $(LDLIBS_libxenguest) $(LDLIBS_libxentoolcore) $(SOCKET_LIBS) -o $@ $(APPEND_LDFLAGS)
 
 xs_tdb_dump: xs_tdb_dump.o utils.o tdb.o talloc.o
 	$(CC) $^ $(LDFLAGS) -o $@ $(APPEND_LDFLAGS)