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Diffstat (limited to 'docs/reference/src/compat/nn_allocmsg.3compat.adoc')
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1 files changed, 67 insertions, 0 deletions
diff --git a/docs/reference/src/compat/nn_allocmsg.3compat.adoc b/docs/reference/src/compat/nn_allocmsg.3compat.adoc new file mode 100644 index 00000000..a53da55c --- /dev/null +++ b/docs/reference/src/compat/nn_allocmsg.3compat.adoc @@ -0,0 +1,67 @@ += nn_allocmsg(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_allocmsg - allocate message (compatible API) + +== SYNOPSIS + +[source,c] +---- +#include <nanomsg/nn.h> + +void *nn_allocmsg(size_t size, int type); +---- + +== DESCRIPTION + +The `nn_allocmsg()` allocates a message structure of size _size_, and is +primarily used to support zero-copy send operations, making use of the +`NNG_MSG` special size indicator. +The value returned is a pointer to the start of the message payload buffer. + +The value of _size_ must be positive, and small enough to hold reasonable +message data plus book-keeping information. + +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 value of _type_ *must* be zero. +(This argument was reserved to support different kinds of memory spaces +for RDMA devices, but this was never developed in the legacy API.) + +The returned message must be disposed of by either +xref:nn_freemsg.3compat.adoc[`nn_freemsg()`] or +xref:nn_send.3compat.adoc[`nn_send()`] when the caller is finished with it. + +== RETURN VALUES + +This function returns a pointer to message buffer space, or `NULL` +on failure. + +== ERRORS + +[horizontal] +`ENOMEM`:: Insufficient memory is available. +`EINVAL`:: An invalid _size_ or _type_ was specified. +`ETERM`:: The library is shutting down. + +== SEE ALSO + +[.text-left] +xref:nn_errno.3compat.adoc[nn_errno(3compat)], +xref:nn_freemsg.3compat.adoc[nn_freemsg(3compat)], +xref:nn_reallocmsg.3compat.adoc[nn_reallocmsg(3compat)], +xref:nn_send.3compat.adoc[nn_send(3compat)], +xref:nng_compat.3compat.adoc[nng_compat(3compat)], +xref:nng.7.adoc[nng(7)] |