sd_bus_slot_set_floating(3) — Linux manual page



NAME         top

       sd_bus_slot_set_floating, sd_bus_slot_get_floating - Control whether
       a bus slot object is "floating"

SYNOPSIS         top

       #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         top

       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

RETURN VALUE         top

       On success, these functions return 0 or a positive integer. On
       failure, they return a negative errno-style error code.

       Returned errors may indicate the following problems:

           The slot parameter is NULL.

           The bus connection has been created in a different process.

           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         top

       These APIs are implemented as a shared library, which can be compiled
       and linked to with the libsystemd pkg-config(1) file.

SEE ALSO         top

       systemd(1), sd-bus(3), sd_bus_slot_set_destroy_callback(3),

COLOPHON         top

       This page is part of the systemd (systemd system and service manager)
       project.  Information about the project can be found at 
       ⟨⟩.  If you have a bug
       report for this manual page, see
       ⟨⟩.  This
       page was obtained from the project's upstream Git repository
       ⟨⟩ on 2020-08-13.  (At that
       time, the date of the most recent commit that was found in the repos‐
       itory was 2020-08-11.)  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

systemd 246                                      SD_BUS_SLOT_SET_FLOATING(3)

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