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116 lines
3.9 KiB
XML
116 lines
3.9 KiB
XML
<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!--
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SPDX-License-Identifier: LGPL-2.1+
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This file is part of systemd.
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Copyright 2016 Julian Orth
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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-->
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<refentry id="sd_bus_message_read_basic">
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<refentryinfo>
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<title>sd_bus_message_read_basic</title>
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<productname>systemd</productname>
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<authorgroup>
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<author>
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<firstname>Julian</firstname>
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<surname>Orth</surname>
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<email>ju.orth@gmail.com</email>
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</author>
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</authorgroup>
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</refentryinfo>
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<refmeta>
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<refentrytitle>sd_bus_message_read_basic</refentrytitle>
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<manvolnum>3</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>sd_bus_message_read_basic</refname>
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<refpurpose>Read a basic type from a message</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<funcsynopsis>
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<funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo>
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<funcprototype>
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<funcdef>int <function>sd_bus_message_read_basic</function></funcdef>
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<paramdef>sd_bus_message *<parameter>m</parameter></paramdef>
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<paramdef>char <parameter>type</parameter></paramdef>
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<paramdef>void *<parameter>p</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para>
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<function>sd_bus_message_read_basic()</function> reads a basic type from a
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message and advances the read position in the message. The set of basic
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types and their ascii codes passed in <parameter>type</parameter> are
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described in the <ulink
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url="https://dbus.freedesktop.org/doc/dbus-specification.html">D-Bus
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Specification</ulink>.
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</para>
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<para>
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If <parameter>p</parameter> is not NULL, it should contain a pointer to an
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appropriate object. For example, if <parameter>type</parameter> is
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<constant>'y'</constant>, the object passed in <parameter>p</parameter>
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should have type <code>uint8_t *</code>. If <parameter>type</parameter>
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is <constant>'s'</constant>, the object passed in <parameter>p</parameter>
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should have type <code>const char **</code>. Note that, if the basic type
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is a pointer (e.g., <code>const char *</code> in the case of a string),
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the pointer is only borrowed and the contents must be copied if they are
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to be used after the end of the messages lifetime. Similarly, during the
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lifetime of such a pointer, the message must not be modified.
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</para>
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<para>
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If there is no object of the specified type at the current position in the
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message, an error is returned.
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</para>
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</refsect1>
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<refsect1>
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<title>Return Value</title>
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<para>
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On success, <function>sd_bus_message_read_basic()</function> returns 0 or
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a positive integer. On failure, it returns a negative errno-style error
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code.
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</para>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<para>
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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</para>
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</refsect1>
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</refentry>
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