x SuSE Linux 13.1-RELEASE x
x SuSE Linux 13.1-RELEASEx
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 - 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.
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 254 SD_BUS_SLOT_REF(3)
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