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[thirdparty/systemd.git] / man / sd_bus_message_read_strv.xml

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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
  "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->

<refentry id="sd_bus_message_read_strv" xmlns:xi="http://www.w3.org/2001/XInclude">

  <refentryinfo>
    <title>sd_bus_message_read_strv</title>
    <productname>systemd</productname>
  </refentryinfo>

  <refmeta>
    <refentrytitle>sd_bus_message_read_strv</refentrytitle>
    <manvolnum>3</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>sd_bus_message_read_strv</refname>
    <refname>sd_bus_message_read_strv_extend</refname>

    <refpurpose>Access an array of strings in a message</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <funcsynopsis>
      <funcsynopsisinfo>#include &lt;systemd/sd-bus.h&gt;</funcsynopsisinfo>

      <funcprototype>
        <funcdef>int <function>sd_bus_message_read_strv</function></funcdef>
        <paramdef>sd_bus_message *<parameter>m</parameter></paramdef>
        <paramdef>char ***<parameter>l</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_message_read_strv_extend</function></funcdef>
        <paramdef>sd_bus_message *<parameter>m</parameter></paramdef>
        <paramdef>char ***<parameter>l</parameter></paramdef>
      </funcprototype>
    </funcsynopsis>
  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>

    <para><function>sd_bus_message_read_strv()</function> reads an array of string-like items from the
    message <parameter>m</parameter>. The "read pointer" in the message must be right before an array of
    strings (D-Bus type <literal>as</literal>), object paths (D-Bus type <literal>ao</literal>), or
    signatures (D-Bus type <literal>ag</literal>). On success, a pointer to a
    <constant>NULL</constant>-terminated array of strings (strv) is returned in the output parameter
    <parameter>l</parameter>. Note that ownership of this array is transferred to the caller. Hence, the
    caller is responsible for freeing this array and its contents.</para>

    <para><function>sd_bus_message_read_strv_extend()</function> is similar, but the second parameter is an
    input-output parameter. If <parameter>*l</parameter> is <constant>NULL</constant>, if behaves identically
    to <function>sd_bus_message_read_strv()</function>. Otherwise, <parameter>*l</parameter> must point to a
    strv, which will be reallocated and extended with additional strings. This function is particularly
    useful when combining multiple lists of strings in a message or messages into a single array of strings.
    </para>
  </refsect1>

  <refsect1>
    <title>Return Value</title>

    <para>On success, these functions return a non-negative integer. On failure, they return a negative
    errno-style error code.</para>

    <refsect2>
      <title>Errors</title>

      <para>Returned errors may indicate the following problems:</para>

      <variablelist>
        <varlistentry>
          <term><constant>-EINVAL</constant></term>

          <listitem><para><parameter>m</parameter> or <parameter>l</parameter> are <constant>NULL</constant>.
          </para>

          <xi:include href="version-info.xml" xpointer="v246"/></listitem>
        </varlistentry>

        <varlistentry>
          <term><constant>-EPERM</constant></term>

          <listitem><para>The message is not sealed.</para>

          <xi:include href="version-info.xml" xpointer="v246"/></listitem>
        </varlistentry>

        <varlistentry>
          <term><constant>-EBADMSG</constant></term>

          <listitem><para>The message cannot be parsed.</para>

          <xi:include href="version-info.xml" xpointer="v246"/></listitem>
        </varlistentry>

        <varlistentry>
          <term><constant>-ENXIO</constant></term>

          <listitem><para>The message "read pointer" is not right before an array of the appropriate type.
          </para>

          <xi:include href="version-info.xml" xpointer="v248"/></listitem>
        </varlistentry>
      </variablelist>
    </refsect2>
  </refsect1>

  <refsect1>
    <title>See Also</title>

    <para>
      <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>sd_bus_message_read</refentrytitle><manvolnum>3</manvolnum></citerefentry>
    </para>
  </refsect1>

</refentry>