man/sd_bus_message_verify_type.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_verify_type" xmlns:xi="http://www.w3.org/2001/XInclude">
  <refentryinfo>
    <title>sd_bus_message_verify_type</title>
    <productname>systemd</productname>
  </refentryinfo>

  <refmeta>
    <refentrytitle>sd_bus_message_verify_type</refentrytitle>
    <manvolnum>3</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>sd_bus_message_verify_type</refname>

    <refpurpose>Check if the message has specified type at the current location</refpurpose>
  </refnamediv>

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

      <funcprototype>
        <funcdef>int sd_bus_message_verify_type</funcdef>
        <paramdef>sd_bus_message *<parameter>m</parameter></paramdef>
        <paramdef>char <parameter>type</parameter></paramdef>
        <paramdef>const char* <parameter>contents</parameter></paramdef>
      </funcprototype>
    </funcsynopsis>
  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>

    <para><function>sd_bus_message_verify_type()</function> checks if the complete type at the
    current location in the message <parameter>m</parameter> matches the specified
    <parameter>type</parameter> and <parameter>contents</parameter>. If non-zero, parameter
    <parameter>type</parameter> must be one of the types specified in
    <citerefentry><refentrytitle>sd_bus_message_append</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
    If non-null, parameter <parameter>contents</parameter> must be a valid sequence of complete
    types. If both <parameter>type</parameter> and <parameter>contents</parameter> are specified
    <parameter>type</parameter> must be a container type.</para>

    <para>If <parameter>type</parameter> is specified, the type in the message must match.  If
    <parameter>contents</parameter> is specified, the type in the message must be a container type
    with this signature.</para>
  </refsect1>

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

    <para>On success, this call returns true if the type matches and zero if not (the message
    <parameter>m</parameter> contains different data or the end of the message has been reached). 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><parameter>m</parameter> or both <parameter>type</parameter> and
          <parameter>contents</parameter> are <constant>NULL</constant>.</para>

          <para>Arguments do not satisfy other constraints listed above.</para>
          </listitem>
        </varlistentry>

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

          <listitem><para>Message <parameter>m</parameter> is not sealed.
          </para></listitem>
        </varlistentry>
      </variablelist>
    </refsect2>
  </refsect1>

  <xi:include href="libsystemd-pkgconfig.xml" />

  <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_append</refentrytitle><manvolnum>3</manvolnum></citerefentry>
    </para>
  </refsect1>

</refentry>