sd_bus_attach_event(3) — Linux manual page


SD_BUS_ATTACH_EVENT(3)     sd_bus_attach_event    SD_BUS_ATTACH_EVENT(3)

NAME         top

       sd_bus_attach_event, sd_bus_detach_event, sd_bus_get_event -
       Attach a bus connection object to an event loop

SYNOPSIS         top

       #include <systemd/sd-bus.h>

       int sd_bus_attach_event(sd_bus *bus, sd_event *e, int priority);

       int sd_bus_detach_event(sd_bus *bus);

       sd_event *sd_bus_get_event(sd_bus *bus);

DESCRIPTION         top

       sd_bus_attach_event() attaches the specified bus connection
       object to an sd-event(3) event loop object at the specified
       priority (see sd_event_source_set_priority(3) for details on
       event loop priorities). When a bus connection object is attached
       to an event loop incoming messages will be automatically read and
       processed, and outgoing messages written, whenever the event loop
       is run. When the event loop is about to terminate, the bus
       connection is automatically flushed and closed (see
       sd_bus_set_close_on_exit(3) for details on this). By default bus
       connection objects are not attached to any event loop. When a bus
       connection object is attached to one it is not necessary to
       invoke sd_bus_wait(3) or sd_bus_process(3) as this functionality
       is handled automatically by the event loop.

       sd_bus_detach_event() detaches a bus object from its event loop.

       The sd_bus_get_event() returns the event loop object the
       specified bus object is currently attached to, or NULL if it is
       currently not attached to any.

       Note that sd_bus_attach_event() is only one of three supported
       ways to implement I/O event handling for bus connections.
       Alternatively use sd_bus_get_fd(3) for hooking up a bus
       connection object with external or manual event loops. Or use
       sd_bus_wait(3) as a simple synchronous, blocking I/O waiting

RETURN VALUE         top

       On success, sd_bus_attach_event() and sd_bus_detach_event()
       return 0 or a positive integer. On failure, they return a
       negative errno-style error code.

       sd_bus_get_event() returns an event loop object or NULL.

       Returned errors may indicate the following problems:

           The bus connection has been created in a different process,
           library or module instance.

NOTES         top

       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

HISTORY         top

       sd_bus_attach_event(), sd_bus_detach_event(), and
       sd_bus_get_event() were added in version 240.

SEE ALSO         top

       systemd(1), sd-bus(3), sd-event(3),
       sd_event_source_set_priority(3), sd_bus_set_close_on_exit(3),
       sd_bus_wait(3), sd_bus_get_fd(3)

COLOPHON         top

       This page is part of the systemd (systemd system and service
       manager) project.  Information about the project can be found at
       ⟨⟩.  If you have
       a bug report for this manual page, see
       This page was obtained from the project's upstream Git repository
       ⟨⟩ on 2023-12-22.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2023-12-22.)  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

systemd 255                                       SD_BUS_ATTACH_EVENT(3)

Pages that refer to this page: sd-bus(3)sd_bus_get_fd(3)sd_bus_process(3)sd_bus_set_close_on_exit(3)sd_bus_set_exit_on_disconnect(3)sd_bus_wait(3)systemd.directives(7)systemd.index(7)