= nng_aio_set_iov(3)
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//
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// Copyright 2021 Staysail Systems, Inc. <info@staysail.tech>
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// Copyright 2018 Capitar IT Group BV <info@capitar.com>
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//
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// This document is supplied under the terms of the MIT License, a
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// copy of which should be located in the distribution where this
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// file was obtained (LICENSE.txt). A copy of the license may also be
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// found online at https://opensource.org/licenses/MIT.
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//
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== NAME
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nng_aio_set_iov - set scatter/gather vector
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== SYNOPSIS
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[source,c]
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----
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#include <nng/nng.h>
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int nng_aio_set_iov(nng_aio *aio, unsigned int niov, nng_iov *iov);
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----
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== DESCRIPTION
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The `nng_aio_set_iov()` function sets a ((scatter/gather)) vector _iov_ on the handle _aio_.
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The _iov_ is a pointer to an array of _niov_ xref:nng_iov.5.adoc[`nng_iov`]
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structures, which have the following definition:
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[source,c]
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----
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typedef struct nng_iov {
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void * iov_buf;
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size_t iov_len;
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};
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----
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The _iov_ is copied into storage in the _aio_ itself, so that callers may use stack allocated `nng_iov` structures.
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The values pointed to by the `iov_buf` members are *not* copied by this function though.
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A maximum of four (4) `nng_iov` members may be supplied.
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NOTE: Earlier versions of the library could accept longer scatter-gather lists.
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However, no known consumers have ever needed a scatter-gather list longer than 4 vectors.
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As a result, the implementation limit was reduced, and heap allocations which could fail were removed.
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== RETURN VALUES
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This function returns 0 on success, and non-zero otherwise.
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== ERRORS
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[horizontal]
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`NNG_EINVAL`:: Value of specified _niov_ is too large.
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== SEE ALSO
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[.text-left]
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xref:nng_aio_alloc.3.adoc[nng_aio_alloc(3)],
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xref:nng_aio_cancel.3.adoc[nng_aio_cancel(3)],
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xref:nng_aio_count.3.adoc[nng_aio_count(3)],
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xref:nng_aio_result.3.adoc[nng_aio_result(3)],
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xref:nng_aio.5.adoc[nng_aio(5)],
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xref:nng_iov.5.adoc[nng_iov(5)],
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xref:nng.7.adoc[nng(7)]
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