1SD_BUS_NEGOTIATE_FDS(3)      sd_bus_negotiate_fds      SD_BUS_NEGOTIATE_FDS(3)
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NAME

6       sd_bus_negotiate_fds, sd_bus_negotiate_timestamp,
7       sd_bus_negotiate_creds - Control feature negotiation on bus connections
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SYNOPSIS

10       #include <systemd/sd-bus.h>
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12       int sd_bus_negotiate_fds(sd_bus *bus, int b);
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14       int sd_bus_negotiate_timestamp(sd_bus *bus, int b);
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16       int sd_bus_negotiate_creds(sd_bus *bus, int b, uint64_t mask);
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DESCRIPTION

19       sd_bus_negotiate_fds() controls whether file descriptor passing shall
20       be negotiated for the specified bus connection. It takes a bus object
21       and a boolean, which, when true, enables file descriptor passing, and,
22       when false, disables it. Note that not all transports and servers
23       support file descriptor passing. In particular, networked transports
24       generally do not support file descriptor passing. To find out whether
25       file descriptor passing is available after negotiation, use
26       sd_bus_can_send(3) and pass SD_BUS_TYPE_UNIX_FD. Note that file
27       descriptor passing is always enabled for both sending and receiving or
28       for neither, but never only in one direction. By default, file
29       descriptor passing is negotiated for all connections.
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31       sd_bus_negotiate_timestamp() controls whether implicit sender
32       timestamps shall be attached automatically to all incoming messages.
33       Takes a bus object and a boolean, which, when true, enables
34       timestamping, and, when false, disables it. Use
35       sd_bus_message_get_monotonic_usec(3),
36       sd_bus_message_get_realtime_usec(3), sd_bus_message_get_seqnum(3) to
37       query the timestamps of incoming messages. If negotiation is disabled
38       or not supported, these calls will fail with -ENODATA. Note that
39       currently no transports support timestamping of messages. By default,
40       message timestamping is not negotiated for connections.
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42       sd_bus_negotiate_creds() controls whether and which implicit sender
43       credentials shall be attached automatically to all incoming messages.
44       Takes a bus object and a boolean indicating whether to enable or
45       disable the credential parts encoded in the bit mask value argument.
46       Note that not all transports support attaching sender credentials to
47       messages, or do not support all types of sender credential parameters,
48       or might suppress them under certain circumstances for individual
49       messages. Specifically, dbus1 only supports SD_BUS_CREDS_UNIQUE_NAME.
50       The sender credentials are suitable for authorization decisions. By
51       default, only SD_BUS_CREDS_WELL_KNOWN_NAMES and
52       SD_BUS_CREDS_UNIQUE_NAME are enabled. In fact, these two credential
53       fields are always sent along and cannot be turned off.
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55       The sd_bus_negotiate_fds() function may be called only before the
56       connection has been started with sd_bus_start(3). Both
57       sd_bus_negotiate_timestamp() and sd_bus_negotiate_creds() may also be
58       called after a connection has been set up. Note that, when operating on
59       a connection that is shared between multiple components of the same
60       program (for example via sd_bus_default(3)), it is highly recommended
61       to only enable additional per message metadata fields, but never
62       disable them again, in order not to disable functionality needed by
63       other components.
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RETURN VALUE

66       On success, these functions return 0 or a positive integer. On failure,
67       they return a negative errno-style error code.
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69   Errors
70       Returned errors may indicate the following problems:
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72       -EPERM
73           The bus connection has already been started.
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NOTES

76       These APIs are implemented as a shared library, which can be compiled
77       and linked to with the libsystemd pkg-config(1) file.
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SEE ALSO

80       systemd(1), sd-bus(3), sd_bus_start(3), sd_bus_message_can_send(3),
81       sd_bus_message_get_monotonic_usec(3),
82       sd_bus_message_get_realtime_usec(3), sd_bus_message_get_seqnum(3),
83       sd_bus_message_get_creds(3)
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87systemd 245                                            SD_BUS_NEGOTIATE_FDS(3)
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