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130 lines
5.0 KiB
XML
130 lines
5.0 KiB
XML
<?xml version='1.0'?>
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
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<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
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<refentry id="sd_bus_message_read_strv" xmlns:xi="http://www.w3.org/2001/XInclude">
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<refentryinfo>
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<title>sd_bus_message_read_strv</title>
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<productname>systemd</productname>
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</refentryinfo>
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<refmeta>
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<refentrytitle>sd_bus_message_read_strv</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_strv</refname>
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<refname>sd_bus_message_read_strv_extend</refname>
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<refpurpose>Access an array of strings in 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_strv</function></funcdef>
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<paramdef>sd_bus_message *<parameter>m</parameter></paramdef>
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<paramdef>char ***<parameter>l</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_bus_message_read_strv_extend</function></funcdef>
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<paramdef>sd_bus_message *<parameter>m</parameter></paramdef>
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<paramdef>char ***<parameter>l</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><function>sd_bus_message_read_strv()</function> reads an array of string-like items from the
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message <parameter>m</parameter>. The "read pointer" in the message must be right before an array of
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strings (D-Bus type <literal>as</literal>), object paths (D-Bus type <literal>ao</literal>), or
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signatures (D-Bus type <literal>ag</literal>). On success, a pointer to a
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<constant>NULL</constant>-terminated array of strings (strv) is returned in the output parameter
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<parameter>l</parameter>. Note that ownership of this array is transferred to the caller. Hence, the
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caller is responsible for freeing this array and its contents. Also note that as a matter of
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optimization, if an empty array is encountered a <constant>NULL</constant> pointer might be returned
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here, and should be considered equivalent to an array with zero entries.</para>
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<para><function>sd_bus_message_read_strv_extend()</function> is similar, but the second parameter is an
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input-output parameter. If <parameter>*l</parameter> is <constant>NULL</constant>, if behaves identically
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to <function>sd_bus_message_read_strv()</function>. Otherwise, <parameter>*l</parameter> must point to a
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strv, which will be reallocated and extended with additional strings. This function is particularly
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useful when combining multiple lists of strings in a message or messages into a single array of strings.
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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>On success, these functions return a non-negative integer. On failure, they return a negative
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errno-style error code.</para>
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<refsect2>
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<title>Errors</title>
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<para>Returned errors may indicate the following problems:</para>
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<variablelist>
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<varlistentry>
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<term><constant>-EINVAL</constant></term>
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<listitem><para><parameter>m</parameter> or <parameter>l</parameter> are <constant>NULL</constant>.
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</para>
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<xi:include href="version-info.xml" xpointer="v246"/></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-EPERM</constant></term>
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<listitem><para>The message is not sealed.</para>
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<xi:include href="version-info.xml" xpointer="v246"/></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-EBADMSG</constant></term>
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<listitem><para>The message cannot be parsed.</para>
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<xi:include href="version-info.xml" xpointer="v246"/></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-ENXIO</constant></term>
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<listitem><para>The message "read pointer" is not right before an array of the appropriate type.
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</para>
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<xi:include href="version-info.xml" xpointer="v248"/></listitem>
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</varlistentry>
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</variablelist>
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</refsect2>
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</refsect1>
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<refsect1>
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<title>History</title>
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<para><function>sd_bus_message_read_strv()</function> was added in version 246.</para>
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<para><function>sd_bus_message_read_strv_extend()</function> was added in version 252.</para>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<para><simplelist type="inline">
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<member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
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<member><citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
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<member><citerefentry><refentrytitle>sd_bus_message_read</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
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</simplelist></para>
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</refsect1>
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</refentry>
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