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NN_RECVMSG(3)			 nanomsg 1.1.5			 NN_RECVMSG(3)

NAME
       nn_recvmsg - fine-grained alternative to	nn_recv

SYNOPSIS
       #include	<nanomsg/nn.h>

       NN_EXPORT int nn_recvmsg	(int s,	struct nn_msghdr *msghdr, int flags);

DESCRIPTION
       Receives	a message from socket s	into buffers specified by msghdr
       parameter along with any	additional control data. msghdr	parameter
       should be nullified before being	used.

       Structure nn_msghdr contains at least following members:

	   struct nn_iovec *msg_iov;
	   int msg_iovlen;
	   void	*msg_control;
	   size_t msg_controllen;

       msg_iov points to a gather array	of buffers to fill in. msg_iovlen
       specifies the size of the array.

       msg_control points to the buffer	to hold	control	information
       associated with the received message. msg_controllen specifies the
       length of the buffer. If	the control information	should not be
       retrieved, set msg_control parameter to NULL. For detailed discussion
       of how to parse the control information check nn_cmsg(3)	man page.

       Structure nn_iovec defines one element in the gather array (a buffer to
       be filled in by message data) and contains following members:

	   void	*iov_base;
	   size_t iov_len;

       Alternatively, nanomsg library can allocate the buffer for you. To do
       so, let the iov_base point to void* variable to receive the buffer and
       set iov_len to NN_MSG. After successful completion user is responsible
       for deallocating	the message using nn_freemsg(3)	function. Gather array
       in nn_msghdr structure can contain only one element in this case.

       The flags argument is a combination of the flags	defined	below:

       NN_DONTWAIT
	   Specifies that the operation	should be performed in non-blocking
	   mode. If the	message	cannot be received straight away, the function
	   will	fail with errno	set to EAGAIN.

RETURN VALUE
       If the function succeeds	number of bytes	in the message is returned.
       Otherwise, -1 is	returned and errno is set to to	one of the values
       defined below.

ERRORS
       EBADF
	   The provided	socket is invalid.

       ENOTSUP
	   The operation is not	supported by this socket type.

       EFSM
	   The operation cannot	be performed on	this socket at the moment
	   because socket is not in the	appropriate state. This	error may
	   occur with socket types that	switch between several states.

       EAGAIN
	   Non-blocking	mode was requested and there's no message to receive
	   at the moment.

       EINTR
	   The operation was interrupted by delivery of	a signal before	the
	   message was received.

       ETIMEDOUT
	   Individual socket types may define their own	specific timeouts. If
	   such	timeout	is hit this error will be returned.

       ETERM
	   The library is terminating.

EXAMPLE
	   struct nn_msghdr hdr;
	   struct nn_iovec iov [2];
	   char	buf0 [4];
	   char	buf1 [2];
	   iov [0].iov_base = buf0;
	   iov [0].iov_len = sizeof (buf0);
	   iov [1].iov_base = buf1;
	   iov [1].iov_len = sizeof (buf1);
	   memset (&hdr, 0, sizeof (hdr));
	   hdr.msg_iov = iov;
	   hdr.msg_iovlen = 2;
	   nn_recvmsg (s, &hdr,	0);

SEE ALSO
       nn_recv(3) nn_sendmsg(3)	nn_allocmsg(3) nn_freemsg(3) nn_cmsg(3)
       nanomsg(7)

AUTHORS
       Martin Sustrik <sustrik@250bpm.com>

				  2018-10-15			 NN_RECVMSG(3)

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLE | SEE ALSO | AUTHORS

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