sd_event_destroy_t(3) — Linux manual page

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

SD_EVENT_SOURCE_SET_DESTROY_CALLBACK(3)_destroy_callback_DESTROY_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 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 man-pages@man7.org

systemd 246                          SD_EVENT_SOURCE_SET_DESTROY_CALLBACK(3)

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