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SD_BUS_SLOT_REF(3) sd_bus_slot_ref SD_BUS_SLOT_REF(3)

NAME

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

SYNOPSIS

#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 *sd_bus_slot_get_bus(sd_bus_slot *m);

DESCRIPTION

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

sd_bus_slot_unref() decreases the 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[1]. 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.

sd_bus_slot_get_bus() returns the bus object that message slot is attached to.

RETURN VALUE

sd_bus_slot_ref() always returns the argument.

sd_bus_slot_unref() always returns NULL.

sd_bus_slot_get_bus() always returns the bus object.

NOTES

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_slot_new_signal(3), sd_bus_call_method_async(3)

NOTES

1.
Clean-up Variable Attribute
https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html
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