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 int sd_bus_request_name(sd_bus *bus, const char *name, uint64_t flags);
14 int sd_bus_request_name_async(sd_bus *bus, sd_bus_slot **slot,
16 const char *name, uint64_t flags,
17 sd_bus_message_handler_t callback,
18 void *userdata);
19 int sd_bus_release_name(sd_bus *bus, const char *name);
21 int sd_bus_release_name_async(sd_bus *bus, sd_bus_slot **slot,
23 const char *name,
24 sd_bus_message_handler_t callback,
25 void *userdata);
26
28 sd_bus_request_name() requests a well-known service name on a bus. It
29 takes a bus connection, a valid bus name and a flags parameter. The
30 flags parameter is a combination of the following flags:
31 SD_BUS_NAME_ALLOW_REPLACEMENT
33 After acquiring the name successfully, permit other peers to take
34 over the name when they try to acquire it with the
35 SD_BUS_NAME_REPLACE_EXISTING flag set. If
36 SD_BUS_NAME_ALLOW_REPLACEMENT is not set on the original request,
37 such a request by other peers will be denied.
38 SD_BUS_NAME_REPLACE_EXISTING
40 Take over the name if it is already acquired by another peer, and
41 that other peer has permitted takeover by setting
42 SD_BUS_NAME_ALLOW_REPLACEMENT while acquiring it.
43 SD_BUS_NAME_QUEUE
45 Queue the acquisition of the name when the name is already taken.
46 sd_bus_request_name() operates in a synchronous fashion: a message
48 requesting the name is sent to the bus broker, and the call waits until
49 the broker responds.
50 sd_bus_request_name_async() is an asynchronous version of
52 sd_bus_release_name(). Instead of waiting for the request to complete,
53 the request message is enqueued. The specified callback will be called
54 when the broker's response is received. If the parameter is specified
55 as NULL a default implementation is used instead which will terminate
56 the connection when the name cannot be acquired. The function returns a
57 slot object in its slot parameter — if it is passed as non-NULL — which
58 may be used as a reference to the name request operation. Use
59 sd_bus_slot_unref(3) to destroy this reference. Note that destroying
60 the reference will not unregister the name, but simply ensure the
61 specified callback is no longer called.
62 sd_bus_release_name() releases an acquired well-known name. It takes a
64 bus connection and a valid bus name as parameters. This function
65 operates synchronously, sending a release request message to the bus
66 broker and waiting for it to reply.
67 sd_bus_release_name_async() is an asynchronous version of
69 sd_bus_release_name(). The specified callback function is called when
70 the name has been released successfully. If specified as NULL a generic
71 implementation is used that ignores the result of the operation. As
72 above, the slot (if non-NULL) is set to an object that may be used to
73 reference the operation.
74 These functions are supported only on bus connections, i.e. connections
76 to a bus broker and not on direct connections.
77
79 On success, these calls return 0 or a positive integer. On failure,
80 these calls return a negative errno-style error code.
81 If SD_BUS_NAME_QUEUE is specified, sd_bus_request_name() will return 0
83 when the name is already taken by another peer and the client has been
84 added to the queue for the name. In that case, the caller can subscribe
85 to "NameOwnerChanged" signals to be notified when the name is
86 successfully acquired. sd_bus_request_name() returns > 0 when the name
87 has immediately been acquired successfully.
88
90 Returned errors may indicate the following problems:
91 -EALREADY
93 The caller already is the owner of the specified name.
94 -EEXIST
96 The name has already been acquired by a different peer, and
97 SD_BUS_NAME_REPLACE_EXISTING was not specified or the other peer
98 did not specify SD_BUS_NAME_ALLOW_REPLACEMENT while acquiring the
99 name.
100 -ESRCH
102 It was attempted to release a name that is currently not registered
103 on the bus.
104 -EADDRINUSE
106 It was attempted to release a name that is owned by a different
107 peer on the bus.
108 -EINVAL
110 A specified parameter is invalid. This is also generated when the
111 requested name is a special service name reserved by the D-Bus
112 specification, or when the operation is requested on a connection
113 that does not refer to a bus.
114 -ENOTCONN
116 The bus connection has been disconnected.
117 -ECHILD
119 The bus connection has been created in a different process than the
120 current one.
121
123 These APIs are implemented as a shared library, which can be compiled
124 and linked to with the libsystemd pkg-config(1) file.
125
127 systemd(1), sd-bus(3), sd_bus_new(3), sd_bus_slot_unref(3)
128systemd 241 SD_BUS_REQUEST_NAME(3)