NAME

       sd_event_source_set_userdata, sd_event_source_get_userdata - Set or retrieve user data pointer of event
       sources

SYNOPSIS

       #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);

DESCRIPTION

       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.

RETURN VALUE

       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.

NOTES

       These APIs are implemented as a shared library, which can be compiled and linked to with the
       libsystemd pkg-config(1) file.

SEE ALSO

       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)