Differential D15204 Diff 42775 head/lib/libc/sys/recv.2

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head/lib/libc/sys/recv.2

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	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT			.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY			.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF			.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	.\" SUCH DAMAGE.			.\" SUCH DAMAGE.
	.\"			.\"
	.\" @(#)recv.2 8.3 (Berkeley) 2/21/94			.\" @(#)recv.2 8.3 (Berkeley) 2/21/94
	.\" $FreeBSD$			.\" $FreeBSD$
	.\"			.\"
	.Dd October 3, 2017			.Dd May 20, 2018
	.Dt RECV 2			.Dt RECV 2
	.Os			.Os
	.Sh NAME			.Sh NAME
	.Nm recv ,			.Nm recv ,
	.Nm recvfrom ,			.Nm recvfrom ,
	.Nm recvmsg ,			.Nm recvmsg ,
	.Nm recvmmsg			.Nm recvmmsg
	.Nd receive message(s) from a socket			.Nd receive message(s) from a socket
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	or the next data to be received is of a different type than that returned.			or the next data to be received is of a different type than that returned.
	The			The
	.Dv MSG_DONTWAIT			.Dv MSG_DONTWAIT
	flag requests the call to return when it would block otherwise.			flag requests the call to return when it would block otherwise.
	If no data is available,			If no data is available,
	.Va errno			.Va errno
	is set to			is set to
	.Er EAGAIN .			.Er EAGAIN .
	This flag is not available in strict			This flag is not available in strict ANSI or C99 compilation mode.
	.Tn ANSI
	or C99 compilation mode.
	The			The
	.Dv MSG_WAITFORONE			.Dv MSG_WAITFORONE
	flag sets MSG_DONTWAIT after the first message has been received.			flag sets MSG_DONTWAIT after the first message has been received.
	This flag is only relevant for			This flag is only relevant for
	.Fn recvmmsg .			.Fn recvmmsg .
	.Pp			.Pp
	The			The
	.Fn recvmsg			.Fn recvmsg
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	is returned to indicate that expedited or out-of-band data were received.			is returned to indicate that expedited or out-of-band data were received.
	.Pp			.Pp
	The			The
	.Fn recvmmsg			.Fn recvmmsg
	system call uses the			system call uses the
	.Fa mmsghdr			.Fa mmsghdr
	structure, defined as follows in the			structure, defined as follows in the
	.In sys/socket.h			.In sys/socket.h
	header :			header:
	.Bd -literal			.Bd -literal
	struct mmsghdr {			struct mmsghdr {
	struct msghdr msg_hdr; /* message header */			struct msghdr msg_hdr; /* message header */
	ssize_t msg_len; /* message length */			ssize_t msg_len; /* message length */
	};			};
	.Ed			.Ed
	.Pp			.Pp
	On data reception the			On data reception the
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