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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | HISTORY | SEE ALSO | COLOPHON |
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SD_EVENT...USERDATA(3) sd_event_source_set_userdataSD_EVENT...USERDATA(3)
sd_event_source_set_userdata, sd_event_source_get_userdata - Set
or retrieve user data pointer of event sources
#include <systemd/sd-event.h>
void* sd_event_source_set_userdata(sd_event_source *source,
void *userdata);
void* sd_event_source_get_userdata(sd_event_source *source);
sd_event_source_set_userdata() may be used to set an arbitrary
user data pointer for the event source object specified as source.
The user data pointer is usually specified when creating an event
source object with calls such as sd_event_add_io(3) or
sd_event_add_time(3), and may be updated with this call. The user
data pointer is also passed to all handler callback functions
associated with the event source. The userdata parameter specifies
the new user data pointer to set, the function returns the
previous user data pointer. Note that NULL is a valid user data
pointer.
sd_event_source_get_userdata() may be used to query the current
user data pointer assigned to the event source object source.
On success, sd_event_source_set_userdata() and
sd_event_source_get_userdata() return the previously set user data
pointer. On failure, they return 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_source_set_userdata() and sd_event_source_get_userdata()
were added in version 229.
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_description(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
[email protected]
systemd 258~rc2 SD_EVENT...USERDATA(3)
Pages that refer to this page: sd-event(3), sd_event_add_child(3), sd_event_add_defer(3), sd_event_add_inotify(3), sd_event_add_io(3), sd_event_add_memory_pressure(3), sd_event_add_signal(3), sd_event_add_time(3), sd_event_source_get_event(3), sd_event_source_set_description(3), sd_event_source_set_destroy_callback(3), sd_event_source_set_prepare(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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