qemu-file: add writable socket QEMUFile

Reviewed-by: Orit Wasserman <owasserm@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
diff --git a/migration-tcp.c b/migration-tcp.c
index e78a296..7d975b5 100644
--- a/migration-tcp.c
+++ b/migration-tcp.c
@@ -95,7 +95,7 @@
         goto out;
     }
 
-    f = qemu_fopen_socket(c);
+    f = qemu_fopen_socket(c, "rb");
     if (f == NULL) {
         fprintf(stderr, "could not qemu_fopen socket\n");
         goto out;