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147 lines
4.1 KiB
147 lines
4.1 KiB
5 years ago
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'\" t
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.\" Title: zmq_msg_init_data
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.\" Author: [see the "AUTHORS" section]
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.\" Generator: DocBook XSL Stylesheets v1.78.1 <http://docbook.sf.net/>
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.\" Date: 09/14/2016
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.\" Manual: 0MQ Manual
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.\" Source: 0MQ 4.1.5
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.\" Language: English
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.\"
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.TH "ZMQ_MSG_INIT_DATA" "3" "09/14/2016" "0MQ 4\&.1\&.5" "0MQ Manual"
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.\" -----------------------------------------------------------------
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.\" * Define some portability stuff
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.\" -----------------------------------------------------------------
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.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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.\" http://bugs.debian.org/507673
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.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html
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.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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.ie \n(.g .ds Aq \(aq
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.el .ds Aq '
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.\" -----------------------------------------------------------------
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.\" * set default formatting
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.\" -----------------------------------------------------------------
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.\" disable hyphenation
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.nh
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.\" disable justification (adjust text to left margin only)
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.ad l
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.\" -----------------------------------------------------------------
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.\" * MAIN CONTENT STARTS HERE *
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.\" -----------------------------------------------------------------
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.SH "NAME"
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zmq_msg_init_data \- initialise 0MQ message from a supplied buffer
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.SH "SYNOPSIS"
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.sp
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\fBtypedef void (zmq_free_fn) (void \fR\fB\fI*data\fR\fR\fB, void \fR\fB\fI*hint\fR\fR\fB);\fR
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.sp
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\fBint zmq_msg_init_data (zmq_msg_t \fR\fB\fI*msg\fR\fR\fB, void \fR\fB\fI*data\fR\fR\fB, size_t \fR\fB\fIsize\fR\fR\fB, zmq_free_fn \fR\fB\fI*ffn\fR\fR\fB, void \fR\fB\fI*hint\fR\fR\fB);\fR
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.SH "DESCRIPTION"
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.sp
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The \fIzmq_msg_init_data()\fR function shall initialise the message object referenced by \fImsg\fR to represent the content referenced by the buffer located at address \fIdata\fR, \fIsize\fR bytes long\&. No copy of \fIdata\fR shall be performed and 0MQ shall take ownership of the supplied buffer\&.
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.sp
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If provided, the deallocation function \fIffn\fR shall be called once the data buffer is no longer required by 0MQ, with the \fIdata\fR and \fIhint\fR arguments supplied to \fIzmq_msg_init_data()\fR\&.
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.if n \{\
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.sp
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.\}
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.RS 4
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.it 1 an-trap
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.nr an-no-space-flag 1
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.nr an-break-flag 1
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.br
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.ps +1
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\fBCaution\fR
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.ps -1
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.br
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.sp
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Never access \fIzmq_msg_t\fR members directly, instead always use the \fIzmq_msg\fR family of functions\&.
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.sp .5v
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.RE
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.if n \{\
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.sp
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.\}
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.RS 4
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.it 1 an-trap
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.nr an-no-space-flag 1
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.nr an-break-flag 1
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.br
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.ps +1
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\fBCaution\fR
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.ps -1
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.br
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.sp
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The deallocation function \fIffn\fR needs to be thread\-safe, since it will be called from an arbitrary thread\&.
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.sp .5v
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.RE
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.if n \{\
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.sp
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.\}
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.RS 4
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.it 1 an-trap
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.nr an-no-space-flag 1
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.nr an-break-flag 1
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.br
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.ps +1
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\fBCaution\fR
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.ps -1
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.br
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.sp
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If the deallocation function is not provided, the allocated memory will not be freed, and this may cause a memory leak\&.
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.sp .5v
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.RE
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.if n \{\
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.sp
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.\}
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.RS 4
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.it 1 an-trap
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.nr an-no-space-flag 1
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.nr an-break-flag 1
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.br
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.ps +1
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\fBCaution\fR
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.ps -1
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.br
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.sp
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The functions \fIzmq_msg_init()\fR, \fIzmq_msg_init_data()\fR and \fIzmq_msg_init_size()\fR are mutually exclusive\&. Never initialize the same \fIzmq_msg_t\fR twice\&.
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.sp .5v
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.RE
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.SH "RETURN VALUE"
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.sp
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The \fIzmq_msg_init_data()\fR function shall return zero if successful\&. Otherwise it shall return \-1 and set \fIerrno\fR to one of the values defined below\&.
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.SH "ERRORS"
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.PP
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\fBENOMEM\fR
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.RS 4
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Insufficient storage space is available\&.
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.RE
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.SH "EXAMPLE"
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.PP
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\fBInitialising a message from a supplied buffer\fR.
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.sp
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.if n \{\
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.RS 4
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.\}
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.nf
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void my_free (void *data, void *hint)
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{
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free (data);
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}
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/* \&.\&.\&. */
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void *data = malloc (6);
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assert (data);
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memcpy (data, "ABCDEF", 6);
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zmq_msg_t msg;
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rc = zmq_msg_init_data (&msg, data, 6, my_free, NULL);
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assert (rc == 0);
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.fi
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.if n \{\
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.RE
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.\}
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.sp
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.SH "SEE ALSO"
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.sp
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\fBzmq_msg_init_size\fR(3) \fBzmq_msg_init\fR(3) \fBzmq_msg_close\fR(3) \fBzmq_msg_data\fR(3) \fBzmq_msg_size\fR(3) \fBzmq\fR(7)
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.SH "AUTHORS"
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.sp
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This page was written by the 0MQ community\&. To make a change please read the 0MQ Contribution Policy at \m[blue]\fBhttp://www\&.zeromq\&.org/docs:contributing\fR\m[]\&.
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