sd_bus_slot_get_bus, sd_bus_slot_get_current_handler, sd_bus_slot_get_current_message, sd_bus_slot_get_current_userdata — Query information attached to a bus slot object
#include <systemd/sd-bus.h>
| typedef int (*sd_bus_message_handler_t)( | sd_bus_message *m, | 
| void *userdata, | |
| sd_bus_error *ret_error ); | 
| sd_bus *sd_bus_slot_get_bus( | sd_bus_slot *slot ); | 
| sd_bus_message_handler_t sd_bus_slot_get_current_handler
        ( | sd_bus_slot *slot ); | 
| sd_bus_message *sd_bus_slot_get_current_message( | sd_bus_slot *slot ); | 
| void *sd_bus_slot_get_current_userdata( | sd_bus_slot *slot ); | 
sd_bus_slot_get_bus() returns the bus object that message
    slot is attached to.
sd_bus_slot_get_current_handler(),
    sd_bus_slot_get_current_message() and
    sd_bus_slot_get_current_userdata() return the current handler, message and
    userdata respectively of the bus slot is attached to if we're currently
    executing the callback associated with slot.
sd_bus_slot_get_bus() always returns the bus object.
On success, sd_bus_slot_get_current_handler(),
    sd_bus_slot_get_current_message() and
    sd_bus_slot_get_current_userdata() return the requested object. On failure,
    they return NULL.
These APIs are implemented as a shared
  library, which can be compiled and linked to with the
  libsystemd pkg-config(1)
  file.