68 lines
2 KiB
Text
68 lines
2 KiB
Text
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= nn_allocmsg(3compat)
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//
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// Copyright 2018 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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nn_allocmsg - allocate message (compatible API)
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== SYNOPSIS
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[source,c]
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----
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#include <nanomsg/nn.h>
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void *nn_allocmsg(size_t size, int type);
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----
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== DESCRIPTION
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The `nn_allocmsg()` allocates a message structure of size _size_, and is
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primarily used to support zero-copy send operations, making use of the
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`NNG_MSG` special size indicator.
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The value returned is a pointer to the start of the message payload buffer.
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The value of _size_ must be positive, and small enough to hold reasonable
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message data plus book-keeping information.
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NOTE: This function is provided for API
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xref:nng_compat.3compat.adoc[compatibility] with legacy _libnanomsg_.
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Consider using the relevant xref:libnng.3.adoc[modern API] instead.
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The value of _type_ *must* be zero.
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(This argument was reserved to support different kinds of memory spaces
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for RDMA devices, but this was never developed in the legacy API.)
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The returned message must be disposed of by either
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xref:nn_freemsg.3compat.adoc[`nn_freemsg()`] or
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xref:nn_send.3compat.adoc[`nn_send()`] when the caller is finished with it.
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== RETURN VALUES
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This function returns a pointer to message buffer space, or `NULL`
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on failure.
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== ERRORS
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[horizontal]
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`ENOMEM`:: Insufficient memory is available.
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`EINVAL`:: An invalid _size_ or _type_ was specified.
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`ETERM`:: The library is shutting down.
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== SEE ALSO
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[.text-left]
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xref:nn_errno.3compat.adoc[nn_errno(3compat)],
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xref:nn_freemsg.3compat.adoc[nn_freemsg(3compat)],
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xref:nn_reallocmsg.3compat.adoc[nn_reallocmsg(3compat)],
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xref:nn_send.3compat.adoc[nn_send(3compat)],
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xref:nng_compat.3compat.adoc[nng_compat(3compat)],
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xref:nng.7.adoc[nng(7)]
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