plugin: add a function to get a descriptor to the image dir

Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

include/criu-plugin.h

@@ -23,4 +23,7 @@
 typedef int (cr_plugin_init_t)(void);
 typedef void (cr_plugin_fini_t)(void);
 
+/* Public API */
+extern int criu_get_image_dir(void);
+
 #endif

util.c

@@ -319,6 +319,11 @@ int get_service_fd(enum sfd_type type)
 	return __get_service_fd(type, service_fd_id);
 }
 
+int criu_get_image_dir(void)
+{
+	return get_service_fd(IMG_FD_OFF);
+}
+
 int close_service_fd(enum sfd_type type)
 {
 	int fd;