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NAMEnn_sendmsg - fine-grained alternative to nn_sendSYNOPSIS#include <nanomsg/nn.h> int nn_sendmsg (int s, const struct nn_msghdr *msghdr , int flags);DESCRIPTIONSends data specified by msghdr parameter to socket s along with any additional control data. msghdr structure 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; void *iov_base; size_t iov_len; Specifies that the operation should be performed in
non-blocking mode. If the message cannot be sent straight away, the function
will fail with errno set to EAGAIN.
RETURN VALUEIf 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.ERRORSEINVALEither msghdr is NULL, there are multiple scatter
buffers but length is set to NN_MSG for one of them, or the sum of
iov_len values for the scatter buffers overflows size_t. These
are early checks and no pre-allocated message is freed in this case.
EMSGSIZE
msghdr→msg_iovlen is negative. This is an early
check and no pre-allocated message is freed in this case.
EFAULT
The supplied pointer for the pre-allocated message buffer
or the scatter buffer is NULL, or the length for the scatter buffer is
0.
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 the message cannot be
sent at the moment.
EINTR
The operation was interrupted by delivery of a signal
before the message was sent.
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.
EXAMPLEUsage of multiple scatter buffers:struct nn_msghdr hdr; struct nn_iovec iov [2]; iov [0].iov_base = "Hello"; iov [0].iov_len = 5; iov [1].iov_base = "World"; iov [1].iov_len = 5; memset (&hdr, 0, sizeof (hdr)); hdr.msg_iov = iov; hdr.msg_iovlen = 2; nn_sendmsg (s, &hdr, 0); void *msg; struct nn_msghdr hdr; struct nn_iovec iov; msg = nn_allocmsg(12, 0); strcpy(msg, "Hello World"); iov.iov_base = &msg; iov.iov_len = NN_MSG; memset (&hdr, 0, sizeof (hdr)); hdr.msg_iov = &iov; hdr.msg_iovlen = 1; nn_sendmsg (s, &hdr, 0); SEE ALSOnn_send(3) nn_recvmsg(3) nn_allocmsg(3) nn_freemsg(3) nn_cmsg(3) nanomsg(7)AUTHORSMartin <sustrik@250bpm.com>Sustrik
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