.TH BUS_POLL 3 BUS-%VERSION%
.SH NAME
bus_poll - Wait a message to be broadcasted
.SH SYNOPSIS
.LP
.nf
#include <bus.h>
.P
int bus_poll_start(bus_t *bus, int flags);
int bus_poll_stop(const bus_t *bus);
const char * bus_poll(bus_t *bus);
.fi
.SH DESCRIPTION
The
.BR bus_poll(3)
function waits for a message to broadcasted on the \fIbus\fP, and return
the message it receives. The function fails if there is not already a
message waiting on the bus when the function is called and (\fIflags\fP
&BUS_NOWAIT) was used the last time
.BR bus_poll_start(3)
was called. Received messages shall be copied and parsed, and acted
upon, in a separate thread, and
.BR bus_poll(3)
or
.BR bus_poll_stop(3)
called again as soon as possible.
.PP
The
.BR bus_poll_start(3)
funcion must be called before
.BR bus_poll(3)
is called for the first time. When the process is done listening on the
bus it must call the
.BR bus_poll_stop(3)
function.
.SH RETURN VALUES
Upon successful completion, the functions
.BR bus_poll_start(3)
and
.BR bus_poll_stop(3)
returns 0.  Otherwise the functions returns -1 and sets \fIerrno\fP to
indicate the error.
.PP
Upon successful completion, the function
.BR bus_poll(3)
returns the received message.  Otherwise the function returns \fINULL\fP
and sets \fIerrno\fP to indicate the error.
.SH ERRORS
The
.BR bus_poll(3),
.BR bus_poll_start(3)
and
.BR bus_poll_stop(3)
functions may fail and set \fIerrno\fP to any of the errors specified for
.BR semop(3).
.SH SEE ALSO
bus-create(1), bus(5), libbus(7), bus_open(3), bus_write(3),
bus_read(3), semop(3)
.SH AUTHORS
Principal author, Mattias Andrée.  See the LICENSE file for the full
list of authors.
.SH LICENSE
MIT/X Consortium License.
.SH BUGS
Please report bugs to https://github.com/maandree/bus/issues or to
maandree@member.fsf.org