Prevent fd leakage by opening new libvirt connections in child.

cloudcontrol/node/hypervisor/__init__.py

@@ -339,14 +339,6 @@ class Handler(HostHandler):
             logger.exception('Cannot find domain %s on hypervisor for live'
                              ' migration', name)
             raise
-        try:
-            dest_virt_con = libvirt.open(
-                'qemu+tcp://127.0.0.1:%d/system' % remote_virt_port)
-        except libvirt.libvirtError:
-            logger.exception('Cannot connect to remote libvirt for live'
-                             ' migrating vm %s', name)
-            raise
-
 
         # we open a new connection to libvirt and fork because sometimes libvirt
         # python binding, while doing a operation,
@@ -356,14 +348,6 @@ class Handler(HostHandler):
         # libvirt connection for the migration and fork, the migration operation
         # in itself is handled by the child while other threads can be scheduled
 
-        # create a new libvirt connection dedicated to migration
-        try:
-            new_con = libvirt.open('qemu:///system')
-            domain = new_con.lookupByUUIDString(vm.uuid)
-        except libvirt.libvirtError:
-            logger.exception('Cannot connect to libvirt')
-            raise
-
         try:
             pid = os.fork()
         except OSError:
@@ -373,6 +357,29 @@ class Handler(HostHandler):
         if pid == 0:
             # child
             # FIXME we should close all unused fds
+            # create a new libvirt connection dedicated to migration
+            try:
+                new_con = libvirt.open('qemu:///system')
+                domain = new_con.lookupByUUIDString(vm.uuid)
+            except libvirt.libvirtError:
+                sys.stderr.write('Cannot connect to libvirt\n')
+                os._exit(4)
+            except:
+                # error
+                # TODO print traceback
+                os._exit(2)
+            try:
+                dest_virt_con = libvirt.open(
+                    'qemu+tcp://127.0.0.1:%d/system' % remote_virt_port)
+            except libvirt.libvirtError:
+                sys.stderr.write('Cannot connect to remote libvirt for live'
+                                 ' migrating vm %s', name)
+                os._exit(5)
+            except:
+                # error
+                # TODO print traceback
+                os._exit(2)
+
             try:
                 if unsafe:
                     # VIR_MIGRATE_UNSAFE is not defined for libvirt < 0.9.11
@@ -398,6 +405,7 @@ class Handler(HostHandler):
             else:
                 os._exit(0)
             finally:
+                new_con.close()
                 dest_virt_con.close()
         else:
             # watch for migration status every second
@@ -437,7 +445,13 @@ class Handler(HostHandler):
                     logger.error('Migration timeout for vm %s', name)
                     raise VMMigrationError('Timeout')
                 else:
-                    if status != 0:
+                    if status == 4:
+                        raise VMMigrationError('Cannot open new connection to'
+                                               ' libvirt')
+                    elif status == 5:
+                        raise VMMigrationError('Cannot open connection to'
+                                               ' remote libvirt')
+                    elif status != 0:
                         # error
                         logger.error('Libvirt error while live migrating vm %s',
                                      name)