1SD_BUS_REQUEST_NAME(3) sd_bus_request_name SD_BUS_REQUEST_NAME(3)
2
3
4
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
13 int sd_bus_request_name(sd_bus *bus, const char *name, uint64_t flags);
14
15 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
20 int sd_bus_release_name(sd_bus *bus, const char *name);
21
22 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 zero or more of the following
31 flags:
32
33 SD_BUS_NAME_ALLOW_REPLACEMENT
34 After acquiring the name successfully, permit other peers to take
35 over the name when they try to acquire it with the
36 SD_BUS_NAME_REPLACE_EXISTING flag set. If
37 SD_BUS_NAME_ALLOW_REPLACEMENT is not set on the original request,
38 such a request by other peers will be denied.
39
40 SD_BUS_NAME_REPLACE_EXISTING
41 Take over the name if it was already acquired by another peer, and
42 that other peer has permitted takeover by setting
43 SD_BUS_NAME_ALLOW_REPLACEMENT while acquiring it.
44
45 SD_BUS_NAME_QUEUE
46 Queue the acquisition of the name when the name is already taken.
47
48 sd_bus_request_name() operates in a synchronous fashion: a message
49 requesting the name is sent to the bus broker, and the call waits until
50 the broker responds.
51
52 sd_bus_request_name_async() is an asynchronous version of
53 sd_bus_release_name(). Instead of waiting for the request to complete,
54 the request message is enqueued. The specified callback will be called
55 when the broker's response is received. If the parameter is specified
56 as NULL a default implementation is used instead which will terminate
57 the connection when the name cannot be acquired. The function returns a
58 slot object in its slot parameter — if it is passed as non-NULL — which
59 may be used as a reference to the name request operation. Use
60 sd_bus_slot_unref(3) to destroy this reference. Note that destroying
61 the reference will not unregister the name, but simply ensure the
62 specified callback is no longer called.
63
64 sd_bus_release_name() releases an acquired well-known name. It takes a
65 bus connection and a valid bus name as parameters. This function
66 operates synchronously, sending a release request message to the bus
67 broker and waiting for it to reply.
68
69 sd_bus_release_name_async() is an asynchronous version of
70 sd_bus_release_name(). The specified callback function is called when
71 the name has been released successfully. If specified as NULL a generic
72 implementation is used that ignores the result of the operation. As
73 above, the slot (if non-NULL) is set to an object that may be used to
74 reference the operation.
75
76 These functions are supported only on bus connections, i.e. connections
77 to a bus broker and not on direct connections.
78
80 On success, these calls return 0 or a positive integer. On failure,
81 these calls return a negative errno-style error code.
82
83 If SD_BUS_NAME_QUEUE is specified, sd_bus_request_name() will return 0
84 when the name is already taken by another peer and the client has been
85 added to the queue for the name. In that case, the caller can subscribe
86 to "NameOwnerChanged" signals to be notified when the name is
87 successfully acquired. sd_bus_request_name() returns > 0 when the name
88 has immediately been acquired successfully.
89
90 Errors
91 Returned errors may indicate the following problems:
92
93 -EALREADY
94 The caller already is the owner of the specified name.
95
96 -EEXIST
97 The name has already been acquired by a different peer, and
98 SD_BUS_NAME_REPLACE_EXISTING was not specified or the other peer
99 did not specify SD_BUS_NAME_ALLOW_REPLACEMENT while acquiring the
100 name.
101
102 -ESRCH
103 It was attempted to release a name that is currently not registered
104 on the bus.
105
106 -EADDRINUSE
107 It was attempted to release a name that is owned by a different
108 peer on the bus.
109
110 -EINVAL
111 A specified parameter is invalid. This is also generated when the
112 requested name is a special service name reserved by the D-Bus
113 specification, or when the operation is requested on a connection
114 that does not refer to a bus.
115
116 -ENOTCONN
117 The bus connection has been disconnected.
118
119 -ECHILD
120 The bus connection has been created in a different process than the
121 current one.
122
124 These APIs are implemented as a shared library, which can be compiled
125 and linked to with the libsystemd pkg-config(1) file.
126
128 systemd(1), sd-bus(3), sd_bus_new(3), sd_bus_slot_unref(3)
129
130
131
132systemd 243 SD_BUS_REQUEST_NAME(3)