Index · Directives systemd 253


sd_bus_slot_ref, sd_bus_slot_unref, sd_bus_slot_unrefp — Create and destroy references to a bus slot object


#include <systemd/sd-bus.h>
sd_bus_slot *sd_bus_slot_ref(sd_bus_slot *slot);
sd_bus_slot *sd_bus_slot_unref(sd_bus_slot *slot);
void sd_bus_slot_unrefp(sd_bus_slot **slotp);


sd_bus_slot_ref() increases the internal reference counter of slot by one.

sd_bus_slot_unref() decreases the internal reference counter of slot by one. Once the reference count has dropped to zero, slot object is destroyed and cannot be used anymore, so further calls to sd_bus_slot_ref() or sd_bus_slot_unref() are illegal.

sd_bus_slot_unrefp() is similar to sd_bus_slot_unref() but takes a pointer to a pointer to an sd_bus_slot object. This call is useful in conjunction with GCC's and LLVM's Clean-up Variable Attribute. See sd_bus_new(3) for an example how to use the cleanup attribute.

sd_bus_slot_ref() and sd_bus_slot_unref() execute no operation if the passed in bus object address is NULL. sd_bus_slot_unrefp() will first dereference its argument, which must not be NULL, and will execute no operation if that is NULL.

Return Value

sd_bus_slot_ref() always returns the argument.

sd_bus_slot_unref() always returns NULL.


These APIs are implemented as a shared library, which can be compiled and linked to with the libsystemd pkg-config(1) file.

See Also

systemd(1), sd-bus(3), sd_bus_new(3), sd_bus_message_new(3), sd_bus_call_method_async(3)