1SD_BUS_REQUEST_NAME(3) sd_bus_request_name SD_BUS_REQUEST_NAME(3)
2
6 sd_bus_request_name, sd_bus_request_name_async, sd_bus_release_name,
7 sd_bus_release_name_async - Request or release a well-known service
8 name on a bus
9
11 #include <systemd/sd-bus.h>
12 typedef int (*sd_bus_message_handler_t)(sd_bus_message *m,
14 void *userdata,
15 sd_bus_error *ret_error);
16 int sd_bus_request_name(sd_bus *bus, const char *name, uint64_t flags);
18 int sd_bus_request_name_async(sd_bus *bus, sd_bus_slot **slot,
20 const char *name, uint64_t flags,
21 sd_bus_message_handler_t callback,
22 void *userdata);
23 int sd_bus_release_name(sd_bus *bus, const char *name);
25 int sd_bus_release_name_async(sd_bus *bus, sd_bus_slot **slot,
27 const char *name,
28 sd_bus_message_handler_t callback,
29 void *userdata);
30
32 sd_bus_request_name() requests a well-known service name on a bus. It
33 takes a bus connection, a valid bus name, and a flags parameter. The
34 flags parameter is a combination of zero or more of the following
35 flags:
36 SD_BUS_NAME_ALLOW_REPLACEMENT
38 After acquiring the name successfully, permit other peers to take
39 over the name when they try to acquire it with the
40 SD_BUS_NAME_REPLACE_EXISTING flag set. If
41 SD_BUS_NAME_ALLOW_REPLACEMENT is not set on the original request,
42 such a request by other peers will be denied.
43 SD_BUS_NAME_REPLACE_EXISTING
45 Take over the name if it was already acquired by another peer, and
46 that other peer has permitted takeover by setting
47 SD_BUS_NAME_ALLOW_REPLACEMENT while acquiring it.
48 SD_BUS_NAME_QUEUE
50 Queue the acquisition of the name when the name is already taken.
51 sd_bus_request_name() operates in a synchronous fashion: a message
53 requesting the name is sent to the bus broker, and the call waits until
54 the broker responds.
55 sd_bus_request_name_async() is an asynchronous version of
57 sd_bus_request_name(). Instead of waiting for the request to complete,
58 the request message is enqueued. The specified callback will be called
59 when the broker's response is received. If the parameter is specified
60 as NULL a default implementation is used instead which will terminate
61 the connection when the name cannot be acquired. The function returns a
62 slot object in its slot parameter — if it is passed as non-NULL — which
63 may be used as a reference to the name request operation. Use
64 sd_bus_slot_unref(3) to destroy this reference. Note that destroying
65 the reference will not unregister the name, but simply ensure the
66 specified callback is no longer called.
67 sd_bus_release_name() releases an acquired well-known name. It takes a
69 bus connection and a valid bus name as parameters. This function
70 operates synchronously, sending a release request message to the bus
71 broker and waiting for it to reply.
72 sd_bus_release_name_async() is an asynchronous version of
74 sd_bus_release_name(). The specified callback function is called when
75 the name has been released successfully. If specified as NULL a generic
76 implementation is used that ignores the result of the operation. As
77 above, the slot (if non-NULL) is set to an object that may be used to
78 reference the operation.
79 These functions are supported only on bus connections, i.e. connections
81 to a bus broker and not on direct connections.
82
84 On success, these calls return 0 or a positive integer. On failure,
85 these calls return a negative errno-style error code.
86 If SD_BUS_NAME_QUEUE is specified, sd_bus_request_name() will return 0
88 when the name is already taken by another peer and the client has been
89 added to the queue for the name. In that case, the caller can subscribe
90 to "NameOwnerChanged" signals to be notified when the name is
91 successfully acquired. sd_bus_request_name() returns > 0 when the name
92 has immediately been acquired successfully.
93 Errors
95 Returned errors may indicate the following problems:
96 -EALREADY
98 The caller already is the owner of the specified name.
99 -EEXIST
101 The name has already been acquired by a different peer, and
102 SD_BUS_NAME_REPLACE_EXISTING was not specified or the other peer
103 did not specify SD_BUS_NAME_ALLOW_REPLACEMENT while acquiring the
104 name.
105 -ESRCH
107 It was attempted to release a name that is currently not registered
108 on the bus.
109 -EADDRINUSE
111 It was attempted to release a name that is owned by a different
112 peer on the bus.
113 -EINVAL
115 A specified parameter is invalid. This is also generated when the
116 requested name is a special service name reserved by the D-Bus
117 specification, or when the operation is requested on a connection
118 that does not refer to a bus.
119 -ENOTCONN
121 The bus connection has been disconnected.
122 -ECHILD
124 The bus connection has been created in a different process than the
125 current one.
126
128 These APIs are implemented as a shared library, which can be compiled
129 and linked to with the libsystemd pkg-config(1) file.
130
132 systemd(1), sd-bus(3), sd_bus_new(3), sd_bus_slot_unref(3)
133systemd 253 SD_BUS_REQUEST_NAME(3)