varlink: implement file descriptor passing

Let's add infrastructure to implement fd passing in varlink, when used
over AF_UNIX.

This will optionally associate one or more fds with a message sent via
varlink and deliver it to the server.

1 files changed, 12 insertions, 0 deletions

diff --git a/src/shared/varlink.h b/src/shared/varlink.h
index ea4e23ff9c..a94f5a7729 100644
--- a/src/shared/varlink.h
+++ b/src/shared/varlink.h
@@ -107,6 +107,18 @@ int varlink_error_errno(Varlink *v, int error);
 int varlink_notify(Varlink *v, JsonVariant *parameters);
 int varlink_notifyb(Varlink *v, ...);
 
+/* Write outgoing fds into the socket (to be associated with the next enqueued message) */
+int varlink_push_fd(Varlink *v, int fd);
+int varlink_dup_fd(Varlink *v, int fd);
+int varlink_reset_fds(Varlink *v);
+
+/* Read incoming fds from the socket (associated with the currently handled message) */
+int varlink_peek_fd(Varlink *v, size_t i);
+int varlink_take_fd(Varlink *v, size_t i);
+
+int varlink_set_allow_fd_passing_input(Varlink *v, bool b);
+int varlink_set_allow_fd_passing_output(Varlink *v, bool b);
+
 /* Bind a disconnect, reply or timeout callback */
 int varlink_bind_reply(Varlink *v, VarlinkReply reply);