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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | HISTORY | SEE ALSO | COLOPHON |
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SD_BUS_SL..._FLOATING(3) sd_bus_slot_set_floatingSD_BUS_SL..._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
made into a regular (non-floating) slot object, otherwise it is
made into a 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,
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.
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.
sd_bus_slot_set_floating() and sd_bus_slot_get_floating() were
added in version 239.
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
⟨http://www.freedesktop.org/wiki/Software/systemd⟩. If you have a
bug report for this manual page, see
⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.
This page was obtained from the project's upstream Git repository
⟨https://github.com/systemd/systemd.git⟩ on 2025-08-11. (At that
time, the date of the most recent commit that was found in the
repository was 2025-08-11.) If you discover any rendering
problems in this HTML version of the page, or you believe there is
a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
[email protected]
systemd 258~rc2 SD_BUS_SL..._FLOATING(3)
Pages that refer to this page: sd-bus(3), sd_bus_add_match(3), sd_bus_add_node_enumerator(3), sd_bus_add_object(3), sd_bus_add_object_manager(3), sd_bus_call(3), sd_bus_default(3), sd_bus_slot_set_destroy_callback(3), systemd.directives(7), systemd.index(7)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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