lvmdbustest: Add test for copy signature

Add test to ensure we detect when a PV signature is copied to a block
device.

test/dbus/lvmdbustest.py

@@ -8,7 +8,7 @@
 #
 # You should have received a copy of the GNU General Public License
 # along with this program. If not, see <http://www.gnu.org/licenses/>.
-
+import os
 import signal
 # noinspection PyUnresolvedReferences
 import subprocess
@@ -2394,6 +2394,30 @@ class TestDbusService(unittest.TestCase):
 			return False
 		return True
 
+	def _block_present_absent(self, block_device, present=False):
+		start = time.time()
+		keep_looping = True
+		while keep_looping and time.time() < start + 3:
+			if present:
+				if (self._lookup(block_device) != "/"):
+					keep_looping = False
+			else:
+				if (self._lookup(block_device) == "/"):
+					keep_looping = False
+
+		if keep_looping:
+			print("Daemon failed to update")
+		else:
+			print("Note: Time for udev update = %f" % (time.time() - start))
+		if present:
+			rc = self._lookup(block_device)
+			self.assertNotEqual(rc, '/')
+			return True
+		else:
+			rc = self._lookup(block_device)
+			self.assertEqual(rc, '/')
+			return True
+
 	def test_wipefs(self):
 		# Ensure we update the status of the daemon if an external process clears a PV
 		pv = self.objs[PV_INT][0]
@@ -2404,21 +2428,46 @@ class TestDbusService(unittest.TestCase):
 
 		if wipe_result:
 			# Need to wait a bit before the daemon will reflect the change
-			start = time.time()
+			self._block_present_absent(pv_device_path, False)
-			found = True
-			while found and time.time() < start + 10:
-				if (self._lookup(pv_device_path) == "/"):
-					found = False
-
-			print("Note: Time for udev update = %f" % (time.time() - start))
-			# Make sure that the service no longer has it
-			rc = self._lookup(pv_device_path)
-			self.assertEqual(rc, '/')
 
 			# Put it back
 			pv_object_path = self._pv_create(pv_device_path)
 			self.assertNotEqual(pv_object_path, '/')
 
+	@staticmethod
+	def _write_signature(device, data=None):
+		fd = os.open(device, os.O_RDWR|os.O_EXCL|os.O_NONBLOCK)
+		existing = os.read(fd, 1024)
+		os.lseek(fd, 0, os.SEEK_SET)
+
+		if data is None:
+			data_copy = bytearray(existing)
+			# Clear lvm signature
+			data_copy[536:536+9] = bytearray(8)
+			os.write(fd, data_copy)
+		else:
+			os.write(fd, data)
+		os.sync()
+		os.close(fd)
+		return existing
+
+	def test_copy_signature(self):
+		# Ensure we update the state of the daemon if an external process copies
+		# a pv signature onto a block device
+		pv = self.objs[PV_INT][0]
+		pv_device_path = pv.Pv.Name
+
+		try:
+			existing = TestDbusService._write_signature(pv_device_path, None)
+			if self._block_present_absent(pv_device_path, False):
+				TestDbusService._write_signature(pv_device_path, existing)
+				self._block_present_absent(pv_device_path, True)
+		finally:
+			# Ensure we put the PV back for sure.
+			rc = self._lookup(pv_device_path)
+			if rc == "/":
+				self._pv_create(pv_device_path)
+
 
 class AggregateResults(object):