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Diffstat (limited to 'docs/reference/src/compat/nn_sendmsg.3compat.adoc')
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diff --git a/docs/reference/src/compat/nn_sendmsg.3compat.adoc b/docs/reference/src/compat/nn_sendmsg.3compat.adoc new file mode 100644 index 00000000..b339bfe6 --- /dev/null +++ b/docs/reference/src/compat/nn_sendmsg.3compat.adoc @@ -0,0 +1,107 @@ += nn_sendmsg(3compat) +// +// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech> +// Copyright 2018 Capitar IT Group BV <info@capitar.com> +// +// This document is supplied under the terms of the MIT License, a +// copy of which should be located in the distribution where this +// file was obtained (LICENSE.txt). A copy of the license may also be +// found online at https://opensource.org/licenses/MIT. +// + +== NAME + +nn_sendmsg - send message (compatible API) + +== SYNOPSIS + +[source, c] +---- +#include <nanomsg/nn.h> + +int nn_sendmsg(int sock, const struct nn_msghdr *hdr, int flags); +---- + +== DESCRIPTION + +The `nn_sendmsg()` function sends the message described by _hdr_ using the +socket _sock_. + +NOTE: This function is provided for API +xref:nng_compat.3compat.adoc[compatibility] with legacy _libnanomsg_. +Consider using the relevant xref:libnng.3.adoc[modern API] instead. + +The _flags_ field may contain the special flag `NN_DONTWAIT`. +In this case, if the socket is unable to accept more data for sending, +the operation shall not block, but instead will fail with the error `EAGAIN`. + +The _hdr_ points to a structure of type `struct nn_msghdr`, which has the +following definition: + +[source, c] +---- +struct nn_iovec { + void * iov_base; + size_t iov_len; +}; + +struct nn_msghdr { + struct nn_iovec *msg_iov; + int msg_iovlen; + void * msg_control; + size_t msg_controllen; +}; +---- + +The `msg_iov` is an array of gather items, permitting the message +to be spread into different memory blocks. +There are `msg_iovlen` elements in this array, each of which +has the base address (`iov_base`) and length (`iov_len`) indicated. + +For buffers allocated for zero copy +(such as by xref:nn_allocmsg.3compat.adoc[`nn_allocmsg()`]), the value +of `iov_base` should be the address of the pointer to the buffer, +rather than the address of the buffer itself. +In this case, the value of `iov_len` should be `NN_MSG`, +as the length is inferred from the allocated message. +If the `msg_iovlen` field is `NN_MSG`, then this function will free +the associated buffer after it is done with it, if it returns successfully. +(If the function returns with an error, then the caller retains ownership +of the associated buffer and may retry the operation or free the buffer +at its choice.) + +The values of `msg_control` and `msg_controllen` describe a buffer +of ancillary data to send the message. +This is currently only useful to provide the message headers +used with xref:nng.7.adoc#raw_mode[raw mode] sockets. +In all other circumstances these fields should be zero. +Details about this structure are covered in +xref:nn_cmsg.3compat.adoc[`nn_cmsg(3compat)`]. + +NOTE: The send operation is performed asynchronously, and may not have +completed before this function returns control to the caller. + +== RETURN VALUES + +This function returns the number of bytes sent on success, and -1 on error. + +== ERRORS + +[horizontal] +`EAGAIN`:: The operation would block. +`EBADF`:: The socket _sock_ is not open. +`EFSM`:: The socket cannot send in this state. +`EINVAL`:: The _hdr_ is invalid. +`ENOTSUP`:: This protocol cannot send. +`ETIMEDOUT`:: Operation timed out. + +== SEE ALSO + +[.text-left] +xref:nn_cmsg.3compat.adoc[nn_cmsg(3compat)], +xref:nn_errno.3compat.adoc[nn_errno(3compat)], +xref:nn_recv.3compat.adoc[nn_recv(3compat)], +xref:nn_send.3compat.adoc[nn_send(3compat)], +xref:nn_socket.3compat.adoc[nn_socket(3compat)], +xref:nng_compat.3compat.adoc[nn_compat(3compat)], +xref:nng.7.adoc[nng(7)] |