sd_event_source_set_destroy_callback(3) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | SEE ALSO | COLOPHON

SD_EVENT_SOURCE_SET_DESTROY_CALLBACK(3)estroy_callbackESTROY_CALLBACK(3)

NAME         top

       sd_event_source_set_destroy_callback,
       sd_event_source_get_destroy_callback, sd_event_destroy_t - Define
       the callback function for resource cleanup

SYNOPSIS         top

       #include <systemd/sd-event.h>

       typedef int (*sd_event_destroy_t)(void *userdata);

       int sd_event_source_set_destroy_callback(sd_event_source *source,
                                                sd_event_destroy_t callback);

       int sd_event_source_get_destroy_callback(sd_event_source *source,
                                                sd_event_destroy_t *callback);

DESCRIPTION         top

       sd_event_source_set_destroy_callback() sets callback as the
       callback function to be called right before the event source
       object source is deallocated. The userdata pointer from the event
       source object will be passed as the userdata parameter. This
       pointer can be set by an argument to the constructor functions,
       see sd_event_add_io(3), or directly, see
       sd_event_source_set_userdata(3). This callback function is called
       even if userdata is NULL. Note that this callback is invoked at a
       time where the event source object itself is already invalidated,
       and executing operations or taking new references to the event
       source object is not permissible.

       sd_event_source_get_destroy_callback() returns the current
       callback for source in the callback parameter.

RETURN VALUE         top

       On success, sd_event_source_set_destroy_callback() returns 0 or a
       positive integer. On failure, it returns a negative errno-style
       error code.

       sd_event_source_get_destroy_callback() returns positive if the
       destroy callback function is set, 0 if not. On failure, returns a
       negative errno-style error code.

   Errors
       Returned errors may indicate the following problems:

       -EINVAL
           The source parameter is NULL.

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-event(3), sd_event_add_io(3),
       sd_event_add_time(3), sd_event_add_signal(3),
       sd_event_add_child(3), sd_event_add_inotify(3),
       sd_event_add_defer(3), sd_event_source_set_userdata(3)

COLOPHON         top

       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 2021-04-01.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2021-04-01.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
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       (which is not part of the original manual page), send a mail to
       man-pages@man7.org

systemd 248                      SD_EVENT_SOURCE_SET_DESTROY_CALLBACK(3)

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