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