sd_bus_request_name(3) — Linux manual page


SD_BUS_REQUEST_NAME(3)     sd_bus_request_name    SD_BUS_REQUEST_NAME(3)

NAME         top

       sd_bus_request_name, sd_bus_request_name_async,
       sd_bus_release_name, sd_bus_release_name_async - Request or
       release a well-known service name on a bus

SYNOPSIS         top

       #include <systemd/sd-bus.h>

       typedef int (*sd_bus_message_handler_t)(sd_bus_message *m,
                                               void *userdata,
                                               sd_bus_error *ret_error);

       int sd_bus_request_name(sd_bus *bus, const char *name,
                               uint64_t flags);

       int sd_bus_request_name_async(sd_bus *bus, sd_bus_slot **slot,
                                     const char *name, uint64_t flags,
                                     sd_bus_message_handler_t callback,
                                     void *userdata);

       int sd_bus_release_name(sd_bus *bus, const char *name);

       int sd_bus_release_name_async(sd_bus *bus, sd_bus_slot **slot,
                                     const char *name,
                                     sd_bus_message_handler_t callback,
                                     void *userdata);

DESCRIPTION         top

       sd_bus_request_name() requests a well-known service name on a
       bus. It takes a bus connection, a valid bus name, and a flags
       parameter. The flags parameter is a combination of zero or more
       of the following flags:

           After acquiring the name successfully, permit other peers to
           take over the name when they try to acquire it with the
           SD_BUS_NAME_REPLACE_EXISTING flag set. If
           SD_BUS_NAME_ALLOW_REPLACEMENT is not set on the original
           request, such a request by other peers will be denied.

           Added in version 209.

           Take over the name if it was already acquired by another
           peer, and that other peer has permitted takeover by setting
           SD_BUS_NAME_ALLOW_REPLACEMENT while acquiring it.

           Added in version 209.

           Queue the acquisition of the name when the name is already

           Added in version 209.

       sd_bus_request_name() operates in a synchronous fashion: a
       message requesting the name is sent to the bus broker, and the
       call waits until the broker responds.

       sd_bus_request_name_async() is an asynchronous version of
       sd_bus_request_name(). Instead of waiting for the request to
       complete, the request message is enqueued. The specified callback
       will be called when the broker's response is received. If the
       parameter is specified as NULL a default implementation is used
       instead which will terminate the connection when the name cannot
       be acquired. The function returns a slot object in its slot
       parameter — if it is passed as non-NULL — which may be used as a
       reference to the name request operation. Use sd_bus_slot_unref(3)
       to destroy this reference. Note that destroying the reference
       will not unregister the name, but simply ensure the specified
       callback is no longer called.

       sd_bus_release_name() releases an acquired well-known name. It
       takes a bus connection and a valid bus name as parameters. This
       function operates synchronously, sending a release request
       message to the bus broker and waiting for it to reply.

       sd_bus_release_name_async() is an asynchronous version of
       sd_bus_release_name(). The specified callback function is called
       when the name has been released successfully. If specified as
       NULL a generic implementation is used that ignores the result of
       the operation. As above, the slot (if non-NULL) is set to an
       object that may be used to reference the operation.

       These functions are supported only on bus connections, i.e.
       connections to a bus broker and not on direct connections.

RETURN VALUE         top

       On success, these calls return 0 or a positive integer. On
       failure, these calls return a negative errno-style error code.

       If SD_BUS_NAME_QUEUE is specified, sd_bus_request_name() will
       return 0 when the name is already taken by another peer and the
       client has been added to the queue for the name. In that case,
       the caller can subscribe to "NameOwnerChanged" signals to be
       notified when the name is successfully acquired.
       sd_bus_request_name() returns > 0 when the name has immediately
       been acquired successfully.

       Returned errors may indicate the following problems:

           The caller already is the owner of the specified name.

           The name has already been acquired by a different peer, and
           SD_BUS_NAME_REPLACE_EXISTING was not specified or the other
           peer did not specify SD_BUS_NAME_ALLOW_REPLACEMENT while
           acquiring the name.

           It was attempted to release a name that is currently not
           registered on the bus.

           It was attempted to release a name that is owned by a
           different peer on the bus.

           A specified parameter is invalid. This is also generated when
           the requested name is a special service name reserved by the
           D-Bus specification, or when the operation is requested on a
           connection that does not refer to a bus.

           The bus connection has been disconnected.

           The bus connection has been created in a different process
           than the current one.

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_request_name() and sd_bus_release_name() were added in
       version 209.

       sd_bus_request_name_async() and sd_bus_release_name_async() were
       added in version 237.

SEE ALSO         top

       systemd(1), sd-bus(3), sd_bus_new(3), sd_bus_slot_unref(3)

COLOPHON         top

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       This page was obtained from the project's upstream Git repository
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systemd 255                                       SD_BUS_REQUEST_NAME(3)

Pages that refer to this page: sd-bus(3)sd_bus_set_watch_bind(3)systemd.directives(7)systemd.index(7)