'\" t
.TH "SD_BUS_IS_OPEN" "3" "" "systemd 255" "sd_bus_is_open"
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.SH "NAME"
sd_bus_is_open, sd_bus_is_ready \- Check whether the bus connection is open or ready
.SH "SYNOPSIS"
.sp
.ft B
.nf
#include <systemd/sd\-bus\&.h>
.fi
.ft
.HP \w'int\ sd_bus_is_open('u
.BI "int sd_bus_is_open(sd_bus\ *" "bus" ");"
.HP \w'int\ sd_bus_is_ready('u
.BI "int sd_bus_is_ready(sd_bus\ *" "bus" ");"
.SH "DESCRIPTION"
.PP
\fBsd_bus_is_open()\fR
checks whether the specified bus connection is open, i\&.e\&. in the process of being established, already established or in the process of being torn down\&. It returns zero when the connection has not been started yet (i\&.e\&.
\fBsd_bus_start\fR(3)
or some equivalent call has not been invoked yet), or is fully terminated again (for example after
\fBsd_bus_close\fR(3)), it returns positive otherwise\&.
.PP
\fBsd_bus_is_ready()\fR
checks whether the specified connection is fully established, i\&.e\&. completed the connection and authentication phases of the protocol and received the
\fBHello()\fR
method call response, and is not in the process of being torn down again\&. It returns zero outside of this state, and positive otherwise\&. Effectively, this function returns positive while regular messages can be sent or received on the connection\&.
.PP
The
\fIbus\fR
argument may be
\fBNULL\fR, zero is also returned in that case\&.
.PP
To be notified when the connection is fully established, use
\fBsd_bus_set_connected_signal\fR(3)
and install a match for the
\fBConnected()\fR
signal on the
"org\&.freedesktop\&.DBus\&.Local"
interface\&. To be notified when the connection is torn down again, install a match for the
\fBDisconnected()\fR
signal on the
"org\&.freedesktop\&.DBus\&.Local"
interface\&.
.SH "RETURN VALUE"
.PP
Those functions return 0 if the bus is
\fInot\fR
in the given state, and a positive integer when it is\&. On failure, a negative errno\-style error code is returned\&.
.SS "Errors"
.PP
Returned errors may indicate the following problems:
.PP
\fB\-ECHILD\fR
.RS 4
The bus connection has been created in a different process, library or module instance\&.
.RE
.SH "NOTES"
.PP
Functions described here are available as a shared library, which can be compiled against and linked to with the
\fBlibsystemd\fR\ \&\fBpkg-config\fR(1)
file\&.
.PP
The code described here uses
\fBgetenv\fR(3), which is declared to be not multi\-thread\-safe\&. This means that the code calling the functions described here must not call
\fBsetenv\fR(3)
from a parallel thread\&. It is recommended to only do calls to
\fBsetenv()\fR
from an early phase of the program when no other threads have been started\&.
.SH "HISTORY"
.PP
\fBsd_bus_is_open()\fR
and
\fBsd_bus_is_ready()\fR
were added in version 237\&.
.SH "SEE ALSO"
.PP
\fBsystemd\fR(1),
\fBsd-bus\fR(3),
\fBsd_bus_start\fR(3),
\fBsd_bus_close\fR(3),
\fBsd_bus_set_connected_signal\fR(3)