sd_bus_send_to(3) — Linux manual page


SD_BUS_SEND(3)                   sd_bus_send                  SD_BUS_SEND(3)

NAME         top

       sd_bus_send, sd_bus_send_to - Queue a D-Bus message for transfer

SYNOPSIS         top

       #include <systemd/sd-bus.h>

       int sd_bus_send(sd_bus *bus, sd_bus_message *m, uint64_t *cookie);

       int sd_bus_send_to(sd_bus *bus, sd_bus_message *m,
                          const char *destination, uint64_t *cookie);

DESCRIPTION         top

       sd_bus_send() queues the bus message object m for transfer. If bus is
       NULL, the bus that m is attached to is used.  bus only needs to be
       set when the message is sent to a different bus than the one it's
       attached to, for example when forwarding messages. If the output
       parameter cookie is not NULL, it is set to the message identifier.
       This value can later be used to match incoming replies to their
       corresponding messages. If cookie is set to NULL and the message is
       not sealed, sd_bus_send() assumes the message m doesn't expect a
       reply and adds the necessary headers to indicate this.

       Note that in most scenarios, sd_bus_send() should not be called
       directly. Instead, use higher level functions such as
       sd_bus_call_method(3) and sd_bus_reply_method_return(3) which call
       sd_bus_send() internally.

       sd_bus_send_to() is a shorthand for sending a message to a specific
       destination. It's main use case is to simplify sending unicast signal
       messages (signals that only have a single receiver). It's behavior is
       similar to calling sd_bus_message_set_destination(3) followed by
       calling sd_bus_send().

       sd_bus_send()/sd_bus_send_to() will write the message directly to the
       underlying transport (e.g. kernel socket buffer) if possible. If the
       connection is not set up fully yet the message is queued locally. If
       the transport buffers are congested any unwritten message data is
       queued locally, too. If the connection has been closed or is
       currently being closed the call fails.  sd_bus_process(3) should be
       invoked to write out any queued message data to the transport.

RETURN VALUE         top

       On success, these functions return a non-negative integer. On
       failure, they return a negative errno-style error code.

       Returned errors may indicate the following problems:

           The input parameter m is NULL.

           The bus connection does not support sending file descriptors.

           The bus connection was allocated in a parent process and is being
           reused in a child process after fork().

           The bus connection's write queue is full.

           The input parameter bus is NULL or the bus is not connected.

           The bus connection was closed while waiting for the response.

           Memory allocation failed.

NOTES         top

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

SEE ALSO         top

       systemd(1), sd-bus(3), sd_bus_call_method(3),
       sd_bus_message_set_destination(3), sd_bus_reply_method_return(3),

COLOPHON         top

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systemd 247                                                   SD_BUS_SEND(3)

Pages that refer to this page: sd-bus(3)30-systemd-environment-d-generator(7)systemd.index(7)