x SuSE Linux 13.1-RELEASE x
x SuSE Linux 13.1-RELEASEx
SD_BUS_SLOT_SET_FLOATING(3)sd_bus_slot_set_floatingSD_BUS_SLOT_SET_FLOATING(3)
NAME
sd_bus_slot_set_floating, sd_bus_slot_get_floating - Control whether a
bus slot object is "floating"
SYNOPSIS
#include <systemd/sd-bus.h>
int sd_bus_slot_set_floating(sd_bus_slot *slot, int b);
int sd_bus_slot_get_floating(sd_bus_slot *slot);
DESCRIPTION
sd_bus_slot_set_floating() controls whether the specified bus slot
object slot shall be "floating" or not. A floating bus slot object's
lifetime is bound to the lifetime of the bus object it is associated
with, meaning that it remains allocated as long as the bus object
itself and is freed automatically when the bus object is freed. Regular
(i.e. non-floating) bus slot objects keep the bus referenced, hence the
bus object remains allocated at least as long as there remains at least
one referenced bus slot object around. The floating state hence
controls the direction of referencing between the bus object and the
bus slot objects: if floating the bus pins the bus slot, and otherwise
the bus slot pins the bus objects. Use sd_bus_slot_set_floating() to
switch between both modes: if the b parameter is zero, the slot object
is considered floating, otherwise it is made a regular (non-floating)
slot object.
Bus slot objects may be allocated with calls such as
sd_bus_add_match(3). If the slot of these functions is non-NULL the
slot object will be of the regular kind (i.e. non-floating), otherwise
it will be created floating. With sd_bus_slot_set_floating() a bus slot
object allocated as regular can be converted into a floating object and
back. This is particularly useful for creating a bus slot object, then
changing parameters of it, and then turning it into a floating object,
whose lifecycle is managed by the bus object.
sd_bus_slot_get_floating() returns the current floating state of the
specified bus slot object. It returns negative on error, zero if the
bus slot object is a regular (non-floating) object and positive
otherwise.
RETURN VALUE
On success, these functions return 0 or a positive integer. On failure,
they return a negative errno-style error code.
Errors
Returned errors may indicate the following problems:
-EINVAL
The slot parameter is NULL.
-ECHILD
The bus connection has been created in a different process, library
or module instance.
-ESTALE
The bus object the specified bus slot object is associated with has
already been freed, and hence no change in the floating state can
be made anymore.
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_slot_set_destroy_callback(3),
sd_bus_add_match(3)
systemd 254 SD_BUS_SLOT_SET_FLOATING(3)
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