systemd sd_event_source_set_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_io3 or sd_event_add_time3, 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. sd_event_source_set_userdata() and sd_event_source_get_userdata() were added in version 229. sd-event3 sd_event_add_io3 sd_event_add_time3 sd_event_add_signal3 sd_event_add_child3 sd_event_add_inotify3 sd_event_add_defer3 sd_event_source_set_description3