bus: rework message handlers to always take an error argument

Message handler callbacks can be simplified drastically if the
dispatcher automatically replies to method calls if errors are returned.

Thus: add an sd_bus_error argument to all message handlers. When we
dispatch a message handler and it returns negative or a set sd_bus_error
we send this as message error back to the client. This means errors
returned by handlers by default are given back to clients instead of
rippling all the way up to the event loop, which is desirable to make
things robust.

As a side-effect we can now easily turn the SELinux checks into normal
function calls, since the method call dispatcher will generate the right
error replies automatically now.

Also, make sure we always pass the error structure to all property and
method handlers as last argument to follow the usual style of passing
variables for return values as last argument.

1 files changed, 5 insertions, 5 deletions

diff --git a/src/core/dbus-unit.h b/src/core/dbus-unit.h
index 859de102b6..57a5e19744 100644
--- a/src/core/dbus-unit.h
+++ b/src/core/dbus-unit.h
@@ -30,10 +30,10 @@ extern const sd_bus_vtable bus_unit_cgroup_vtable[];
 void bus_unit_send_change_signal(Unit *u);
 void bus_unit_send_removed_signal(Unit *u);
 
-int bus_unit_method_start_generic(sd_bus *bus, sd_bus_message *message, Unit *u, JobType job_type, bool reload_if_possible);
-int bus_unit_method_kill(sd_bus *bus, sd_bus_message *message, void *userdata);
-int bus_unit_method_reset_failed(sd_bus *bus, sd_bus_message *message, void *userdata);
+int bus_unit_method_start_generic(sd_bus *bus, sd_bus_message *message, Unit *u, JobType job_type, bool reload_if_possible, sd_bus_error *error);
+int bus_unit_method_kill(sd_bus *bus, sd_bus_message *message, void *userdata, sd_bus_error *error);
+int bus_unit_method_reset_failed(sd_bus *bus, sd_bus_message *message, void *userdata, sd_bus_error *error);
 
-int bus_unit_queue_job(sd_bus *bus, sd_bus_message *message, Unit *u, JobType type, JobMode mode, bool reload_if_possible);
+int bus_unit_queue_job(sd_bus *bus, sd_bus_message *message, Unit *u, JobType type, JobMode mode, bool reload_if_possible, sd_bus_error *error);
 int bus_unit_set_properties(Unit *u, sd_bus_message *message, UnitSetPropertiesMode mode, bool commit, sd_bus_error *error);
-int bus_unit_method_set_properties(sd_bus *bus, sd_bus_message *message, void *userdata);
+int bus_unit_method_set_properties(sd_bus *bus, sd_bus_message *message, void *userdata, sd_bus_error *error);