migration: add helpers for creating QEMUFile from a QIOChannel

Currently creating a QEMUFile instance from a QIOChannel is
quite simple only requiring a single call to
qemu_fopen_channel_input or  qemu_fopen_channel_output
depending on the end of migration connection.

When QEMU gains TLS support, however, there will need to be
a TLS negotiation done inbetween creation of the QIOChannel
and creation of the final QEMUFile. Introduce some helper
methods that will encapsulate this logic, isolating the
migration protocol drivers from knowledge about TLS.
Reviewed-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
Acked-by: NJuan Quintela <quintela@redhat.com>
Message-Id: <1461751518-12128-10-git-send-email-berrange@redhat.com>
Signed-off-by: NAmit Shah <amit.shah@redhat.com>

include/migration/migration.h

@@ -179,6 +179,12 @@ void process_incoming_migration(QEMUFile *f);
 
 void qemu_start_incoming_migration(const char *uri, Error **errp);
 
+void migration_set_incoming_channel(MigrationState *s,
+                                    QIOChannel *ioc);
+
+void migration_set_outgoing_channel(MigrationState *s,
+                                    QIOChannel *ioc);
+
 uint64_t migrate_max_downtime(void);
 
 void exec_start_incoming_migration(const char *host_port, Error **errp);

migration/migration.c

@@ -428,6 +428,27 @@ void process_incoming_migration(QEMUFile *f)
     qemu_coroutine_enter(co, f);
 }
 
+
+void migration_set_incoming_channel(MigrationState *s,
+                                    QIOChannel *ioc)
+{
+    QEMUFile *f = qemu_fopen_channel_input(ioc);
+
+    process_incoming_migration(f);
+}
+
+
+void migration_set_outgoing_channel(MigrationState *s,
+                                    QIOChannel *ioc)
+{
+    QEMUFile *f = qemu_fopen_channel_output(ioc);
+
+    s->to_dst_file = f;
+
+    migrate_fd_connect(s);
+}
+
+
 /*
  * Send a message on the return channel back to the source
  * of the migration.