75 lines
2.5 KiB
Text
75 lines
2.5 KiB
Text
= nn_recv(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_recv - receive data (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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int nn_recv(int sock, void *data, size_t size, int flags)
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----
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== DESCRIPTION
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The `nn_recv()` function receives a message from the socket _sock_.
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The message body must fit within _size_ bytes, and will be stored
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at the location specified by _data_, unless _size_ is the
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special value `NN_MSG`, indicating a zero-copy operation.
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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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If _size_ has the special value `NN_MSG`, then a zero-copy operation
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is performed.
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In this case, instead of copying the message data into the address
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specified by _data_, a new message large enough to hold the message data
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will be allocated (as if by the
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function xref:nn_allocmsg.3compat.adoc[`nn_allocmsg()`]), and the message
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payload will be stored accordingly.
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In this case, the value stored at _data_ will not be message data,
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but a pointer to the message itself.
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In this case, on success, the caller shall take responsibility for
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the final disposition of the message (such as by sending it to
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another peer using xref:nn_send.3compat.adoc[`nn_send()`]) or
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xref:nn_freemsg.3compat.adoc[`nn_freemsg()`].
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The _flags_ field may contain the special flag `NN_DONTWAIT`.
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In this case, if the no message is available for immediate receipt,
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the operation shall not block, but instead will fail with the error `EAGAIN`.
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== RETURN VALUES
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This function returns the number of bytes sent on success, and -1 on error.
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== ERRORS
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[horizontal]
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`EAGAIN`:: The operation would block.
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`EBADF`:: The socket _sock_ is not open.
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`EFSM`:: The socket cannot receive in this state.
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`ENOTSUP`:: This protocol cannot receive.
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`ETIMEDOUT`:: Operation timed out.
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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_recvmsg.3compat.adoc[nn_recvmsg(3compat)],
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xref:nn_send.3compat.adoc[nn_send(3compat)],
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xref:nn_socket.3compat.adoc[nn_socket(3compat)],
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xref:nng_compat.3compat.adoc[nn_compat(3compat)],
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xref:nng.7.adoc[nng(7)]
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