1SD_BUS_NEGOTIATE_FDS(3) sd_bus_negotiate_fds SD_BUS_NEGOTIATE_FDS(3)
2
6 sd_bus_negotiate_fds, sd_bus_negotiate_timestamp,
7 sd_bus_negotiate_creds, sd_bus_get_creds_mask - Control feature
8 negotiation on bus connections
9
11 #include <systemd/sd-bus.h>
12 int sd_bus_negotiate_fds(sd_bus *bus, int b);
14 int sd_bus_negotiate_timestamp(sd_bus *bus, int b);
16 int sd_bus_negotiate_creds(sd_bus *bus, int b, uint64_t mask);
18 int sd_bus_get_creds_mask(sd_bus *bus, uint64_t *mask);
20
22 sd_bus_negotiate_fds() controls whether file descriptor passing shall
23 be negotiated for the specified bus connection. It takes a bus object
24 and a boolean, which, when true, enables file descriptor passing, and,
25 when false, disables it. Note that not all transports and servers
26 support file descriptor passing. In particular, networked transports
27 generally do not support file descriptor passing. To find out whether
28 file descriptor passing is available after negotiation, use
29 sd_bus_can_send(3) and pass SD_BUS_TYPE_UNIX_FD. Note that file
30 descriptor passing is always enabled for both sending and receiving or
31 for neither, but never only in one direction. By default, file
32 descriptor passing is negotiated for all connections.
33 sd_bus_negotiate_timestamp() controls whether implicit sender
35 timestamps shall be attached automatically to all incoming messages.
36 Takes a bus object and a boolean, which, when true, enables
37 timestamping, and, when false, disables it. Use
38 sd_bus_message_get_monotonic_usec(3),
39 sd_bus_message_get_realtime_usec(3), sd_bus_message_get_seqnum(3) to
40 query the timestamps of incoming messages. If negotiation is disabled
41 or not supported, these calls will fail with -ENODATA. Note that
42 currently no transports support timestamping of messages. By default,
43 message timestamping is not negotiated for connections.
44 sd_bus_negotiate_creds() controls whether and which implicit sender
46 credentials shall be attached automatically to all incoming messages.
47 Takes a bus object and a boolean indicating whether to enable or
48 disable the credential parts encoded in the bit mask value argument.
49 Note that not all transports support attaching sender credentials to
50 messages, or do not support all types of sender credential parameters,
51 or might suppress them under certain circumstances for individual
52 messages. Specifically, dbus1 only supports SD_BUS_CREDS_UNIQUE_NAME.
53 The sender credentials are suitable for authorization decisions. By
54 default, only SD_BUS_CREDS_WELL_KNOWN_NAMES and
55 SD_BUS_CREDS_UNIQUE_NAME are enabled. In fact, these two credential
56 fields are always sent along and cannot be turned off.
57 sd_bus_get_creds_mask() returns the set of sender credentials that was
59 negotiated to be attached to all incoming messages in mask. This value
60 is an upper boundary only. Hence, always make sure to explicitly check
61 which credentials are attached to a specific message before using it.
62 The sd_bus_negotiate_fds() function may be called only before the
64 connection has been started with sd_bus_start(3). Both
65 sd_bus_negotiate_timestamp() and sd_bus_negotiate_creds() may also be
66 called after a connection has been set up. Note that, when operating on
67 a connection that is shared between multiple components of the same
68 program (for example via sd_bus_default(3)), it is highly recommended
69 to only enable additional per message metadata fields, but never
70 disable them again, in order not to disable functionality needed by
71 other components.
72
74 On success, these functions return a non-negative integer. On failure,
75 they return a negative errno-style error code.
76 Errors
78 Returned errors may indicate the following problems:
79 -EPERM
81 The bus connection has already been started.
82 -EINVAL
84 An argument is invalid.
85 -ENOPKG
87 The bus cannot be resolved.
88 -ECHILD
90 The bus was created in a different process, library or module
91 instance.
92
94 Functions described here are available as a shared library, which can
95 be compiled against and linked to with the libsystemd pkg-config(1)
96 file.
97 The code described here uses getenv(3), which is declared to be not
99 multi-thread-safe. This means that the code calling the functions
100 described here must not call setenv(3) from a parallel thread. It is
101 recommended to only do calls to setenv() from an early phase of the
102 program when no other threads have been started.
103
105 systemd(1), sd-bus(3), sd_bus_start(3), sd_bus_can_send(3),
106 sd_bus_message_get_monotonic_usec(3),
107 sd_bus_message_get_realtime_usec(3), sd_bus_message_get_seqnum(3),
108 sd_bus_message_get_creds(3)
109systemd 254 SD_BUS_NEGOTIATE_FDS(3)