|
NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | SEE ALSO | COLOPHON |
SD_BUS_SLOT_SET_FLOATING(3)d_bus_slot_set_floatingD_BUS_SLOT_SET_FLOATING(3)
sd_bus_slot_set_floating, sd_bus_slot_get_floating - Control whether
a bus slot object is "floating"
#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);
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.
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.
-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.
These APIs are implemented as a shared library, which can be compiled
and linked to with the libsystemd pkg-config(1) file.
systemd(1), sd-bus(3), sd_bus_slot_set_destroy_callback(3),
sd_bus_add_match(3)
This page is part of the systemd (systemd system and service manager)
project. Information about the project can be found at
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report for this manual page, see
⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩. This
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systemd 246 SD_BUS_SLOT_SET_FLOATING(3)
Pages that refer to this page: 30-systemd-environment-d-generator(7) , systemd.index(7)