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<refentry id="sd_bus_message_read_array">

  <refentryinfo>
    <title>sd_bus_message_read_array</title>
    <productname>systemd</productname>
  </refentryinfo>

  <refmeta>
    <refentrytitle>sd_bus_message_read_array</refentrytitle>
    <manvolnum>3</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>sd_bus_message_read_array</refname>

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

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

      <funcprototype>
        <funcdef>int <function>sd_bus_message_read_array</function></funcdef>
        <paramdef>sd_bus_message *<parameter>m</parameter></paramdef>
        <paramdef>char <parameter>type</parameter></paramdef>
        <paramdef>const void **<parameter>ptr</parameter></paramdef>
        <paramdef>size_t *<parameter>size</parameter></paramdef>
      </funcprototype>
    </funcsynopsis>
  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>

    <para><function>sd_bus_message_read_array()</function> gives access to an element array in
    message <parameter>m</parameter>. The "read pointer" in the message must be right before an
    array of type <parameter>type</parameter>. As a special case, <parameter>type</parameter> may be
    <constant>NUL</constant>, in which case any type is acceptable. A pointer to the array data is
    returned in the parameter <parameter>ptr</parameter> and the size of array data (in bytes) is
    returned in the parameter <parameter>size</parameter>. If <parameter>size</parameter> is 0, a
    valid non-null pointer will be returned, but it may not be dereferenced. The data is aligned as
    appropriate for the data type. The data is part of the message — it may not be modified and is
    valid only as long as the message is referenced. After this function returns, the "read pointer"
    points at the next element after the array.</para>
  </refsect1>

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

    <para>
      On success, <function>sd_bus_message_read_array()</function> returns 0 or
      a positive integer. On failure, it returns 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>Specified type is invalid or the message parameter or one of the output
          parameters are <constant>NULL</constant>.</para></listitem>
        </varlistentry>

        <varlistentry>
          <term><constant>-EOPNOTSUPP</constant></term>

          <listitem><para>The byte order in the message is different than native byte
          order.</para></listitem>
        </varlistentry>

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

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

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

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