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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | HISTORY | SEE ALSO | COLOPHON |
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SD_EV...LBACK(3) sd_event_source_set_destroy_callback SD_EV...LBACK(3)
sd_event_source_set_destroy_callback,
sd_event_source_get_destroy_callback, sd_event_destroy_t - Define
the callback function for resource cleanup
#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);
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.
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.
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_event_destroy_t(), sd_event_source_set_destroy_callback(), and
sd_event_source_get_destroy_callback() were added in version 239.
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)
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 2024-06-14. (At that
time, the date of the most recent commit that was found in the
repository was 2024-06-13.) 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 257~devel SD_EV...LBACK(3)
Pages that refer to this page: systemd.directives(7), systemd.index(7)
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HTML rendering created 2024-06-26 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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