From 6f8944a96a5acd509014caae4e57dafbba51e126 Mon Sep 17 00:00:00 2001 From: Garrett D'Amore Date: Sat, 30 Mar 2024 22:14:33 -0700 Subject: finished proto open pages --- docs/reference/src/compat/nn_recvmsg.3compat.adoc | 99 +++++++++++++++++++++++ 1 file changed, 99 insertions(+) create mode 100644 docs/reference/src/compat/nn_recvmsg.3compat.adoc (limited to 'docs/reference/src/compat/nn_recvmsg.3compat.adoc') diff --git a/docs/reference/src/compat/nn_recvmsg.3compat.adoc b/docs/reference/src/compat/nn_recvmsg.3compat.adoc new file mode 100644 index 00000000..e0fcc758 --- /dev/null +++ b/docs/reference/src/compat/nn_recvmsg.3compat.adoc @@ -0,0 +1,99 @@ += nn_recvmsg(3compat) +// +// Copyright 2018 Staysail Systems, Inc. +// Copyright 2018 Capitar IT Group BV +// +// 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_recvmsg - receive message (compatible API) + +== SYNOPSIS + +[source, c] +---- +#include + +int nn_recvmsg(int sock, struct nn_msghdr *hdr, int flags); +---- + +== DESCRIPTION + +The `nn_recvmsg()` function receives a message into the header 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 no message is ready for receiving on _sock_, +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 scatter 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. + +The last member of this array may have the `iov_len` field set to `NN_MSG`, +in which case the function shall allocate a message buffer, and store the +pointer to it at the address indicated by `iov_base`. +This can help save an extra copy operation. +The buffer should be deallocated by xref:nn_freemsg.3compat.adoc[`nn_freemsg()`] +or similar when it is no longer needed. + +The values of `msg_control` and `msg_controllen` describe a buffer +of ancillary data associated with the message. +This is currently only useful to obtain 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)`]. + +== RETURN VALUES + +This function returns the number of bytes received on success, and -1 on error. + +== ERRORS + +[horizontal] +`EAGAIN`:: The operation would block. +`EBADF`:: The socket _sock_ is not open. +`EFSM`:: The socket cannot receive in this state. +`EINVAL`:: The _hdr_ is invalid. +`ENOTSUP`:: This protocol cannot receive. +`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)] -- cgit v1.2.3-70-g09d2