|
NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | SEE ALSO | COLOPHON |
SD_BUS_REQUEST_NAME(3) sd_bus_request_name SD_BUS_REQUEST_NAME(3)
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
#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);
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:
SD_BUS_NAME_ALLOW_REPLACEMENT
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.
SD_BUS_NAME_REPLACE_EXISTING
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.
SD_BUS_NAME_QUEUE
Queue the acquisition of the name when the name is already taken.
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_release_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.
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.
Errors
Returned errors may indicate the following problems:
-EALREADY
The caller already is the owner of the specified name.
-EEXIST
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.
-ESRCH
It was attempted to release a name that is currently not
registered on the bus.
-EADDRINUSE
It was attempted to release a name that is owned by a different
peer on the bus.
-EINVAL
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.
-ENOTCONN
The bus connection has been disconnected.
-ECHILD
The bus connection has been created in a different process than
the current one.
These APIs are implemented as a shared library, which can be compiled
and linked to with the libsystemd pkg-config(1) file.
systemd(1), sd-bus(3), sd_bus_new(3), sd_bus_slot_unref(3)
This page is part of the systemd (systemd system and service manager)
project. Information about the project can be found at
⟨http://www.freedesktop.org/wiki/Software/systemd⟩. If you have a bug
report for this manual page, see
⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩. This
page was obtained from the project's upstream Git repository
⟨https://github.com/systemd/systemd.git⟩ on 2020-08-13. (At that
time, the date of the most recent commit that was found in the repos‐
itory was 2020-08-11.) 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
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of the original manual page), send a mail to man-pages@man7.org
systemd 246 SD_BUS_REQUEST_NAME(3)
Pages that refer to this page: 30-systemd-environment-d-generator(7) , systemd.index(7)