sd_event_source_set_userdata - Man Page

#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​.

All functions listed here are thread-agnostic and only a single thread may operate on a given object at any given time​. Different threads may access the same object at different times​. Multiple independent objects may be used from different threads in parallel​.

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)

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).

The man page sd_event_source_get_userdata(3) is an alias of sd_event_source_set_userdata(3).