NAME

       sd_bus_slot_ref, sd_bus_slot_unref, sd_bus_slot_unrefp - 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);

DESCRIPTION

       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[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.

RETURN VALUE

       sd_bus_slot_ref() always returns the argument.

       sd_bus_slot_unref() always returns NULL.

NOTES

       Functions described here are available as a shared library, which can be compiled against and linked to
       with the libsystemd pkg-config(1) file.

       The code described here uses getenv(3), which is declared to be not multi-thread-safe. This means that
       the code calling the functions described here must not call setenv(3) from a parallel thread. It is
       recommended to only do calls to setenv() from an early phase of the program when no other threads have
       been started.

HISTORY

       sd_bus_slot_ref(), sd_bus_slot_unref(), and sd_bus_slot_unrefp() were added in version 240.

SEE ALSO

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

NOTES

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

systemd 257.4                                                                                 SD_BUS_SLOT_REF(3)