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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | HISTORY | SEE ALSO | COLOPHON |
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SD_BUS_...ALLBACK(3) sd_bus_slot_set_destroy_callbackSD_BUS_...ALLBACK(3)
sd_bus_slot_set_destroy_callback,
sd_bus_slot_get_destroy_callback,
sd_bus_track_set_destroy_callback,
sd_bus_track_get_destroy_callback, sd_bus_destroy_t - Define the
callback function for resource cleanup
#include <systemd/sd-bus.h>
typedef int (*sd_bus_destroy_t)(void *userdata);
int sd_bus_slot_set_destroy_callback(sd_bus_slot *slot,
sd_bus_destroy_t callback);
int sd_bus_slot_get_destroy_callback(sd_bus_slot *slot,
sd_bus_destroy_t *callback);
int sd_bus_track_set_destroy_callback(sd_bus_track *track,
sd_bus_destroy_t callback);
int sd_bus_track_get_destroy_callback(sd_bus_track *track,
sd_bus_destroy_t *callback);
sd_bus_slot_set_destroy_callback() sets callback as the callback
function to be called right before the bus slot object slot is
deallocated. The userdata pointer from the slot object will be
passed as the userdata parameter. This pointer can be set by an
argument to the constructor functions, see sd_bus_add_match(3), or
directly, see sd_bus_slot_set_userdata(3). This callback function
is called even if userdata is NULL. Note that this callback is
invoked at a time where the bus slot object itself is already
invalidated, and executing operations or taking new references to
the bus slot object is not permissible.
sd_bus_slot_get_destroy_callback() returns the current callback
for slot in the callback parameter.
sd_bus_track_set_destroy_callback() and
sd_bus_track_get_destroy_callback() provide equivalent
functionality for the userdata pointer associated with bus peer
tracking objects. For details about bus peer tracking objects, see
sd_bus_track_new(3).
On success, sd_bus_slot_set_destroy_callback() and
sd_bus_track_set_destroy_callback() return 0 or a positive
integer. On failure, they return a negative errno-style error
code.
sd_bus_slot_get_destroy_callback() and
sd_bus_track_get_destroy_callback() return positive if the destroy
callback function is set, 0 if not. On failure, they return a
negative errno-style error code.
Errors
Returned errors may indicate the following problems:
-EINVAL
The slot or track parameter is NULL.
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_destroy_t(), sd_bus_slot_set_destroy_callback(),
sd_bus_slot_get_destroy_callback(),
sd_bus_track_set_destroy_callback(), and
sd_bus_track_get_destroy_callback() were added in version 239.
systemd(1), sd-bus(3), sd_bus_slot_set_floating(3),
sd_bus_add_match(3), sd_bus_track_new(3),
sd_bus_slot_set_userdata(3), sd_bus_track_set_userdata(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
man-pages@man7.org
systemd 258~rc2 SD_BUS_...ALLBACK(3)
Pages that refer to this page: sd-bus(3), sd_bus_slot_set_floating(3), sd_bus_slot_set_userdata(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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