x SuSE Linux 13.1-RELEASE x
x SuSE Linux 13.1-RELEASEx
SD_BUS_SEND(3) sd_bus_send SD_BUS_SEND(3)
NAME
sd_bus_send, sd_bus_send_to, sd_bus_message_send - Queue a D-Bus
message for transfer
SYNOPSIS
#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);
int sd_bus_message_send(sd_bus_message *m);
DESCRIPTION
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.
sd_bus_message_send() is the same as sd_bus_send() but without the
first and last argument. sd_bus_message_send(m) is equivalent to
sd_bus_send(sd_bus_message_get_bus(m), m, NULL).
RETURN VALUE
On success, these functions return a non-negative integer. On failure,
they return a negative errno-style error code.
Errors
Returned errors may indicate the following problems:
-EINVAL
The input parameter m is NULL.
-EOPNOTSUPP
The bus connection does not support sending file descriptors.
-ECHILD
The bus connection was allocated in a parent process and is being
reused in a child process after fork().
-ENOBUFS
The bus connection's write queue is full.
-ENOTCONN
The input parameter bus is NULL or the bus is not connected.
-ECONNRESET
The bus connection was closed while waiting for the response.
-ENOMEM
Memory allocation failed.
NOTES
Functions described here are available as a shared library, which can
be compiled against and linked to with the libsystemd pkg-config(1)
file.
The code described here uses getenv(3), which is declared to be not
multi-thread-safe. This means that the code calling the functions
described here must not call setenv(3) from a parallel thread. It is
recommended to only do calls to setenv() from an early phase of the
program when no other threads have been started.
SEE ALSO
systemd(1), sd-bus(3), sd_bus_call_method(3),
sd_bus_message_set_destination(3), sd_bus_reply_method_return(3),
sd_bus_process(3)
systemd 254 SD_BUS_SEND(3)
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