man/sd_bus_message_get_type.xml

   1 <?xml version='1.0'?> <!--*-nxml-*-->
   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   3   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
   4 <!-- SPDX-License-Identifier: LGPL-2.1+ -->
   5
   6 <refentry id="sd_bus_message_get_type" xmlns:xi="http://www.w3.org/2001/XInclude">
   7
   8   <refentryinfo>
   9     <title>sd_bus_message_get_type</title>
  10     <productname>systemd</productname>
  11   </refentryinfo>
  12
  13   <refmeta>
  14     <refentrytitle>sd_bus_message_get_type</refentrytitle>
  15     <manvolnum>3</manvolnum>
  16   </refmeta>
  17
  18   <refnamediv>
  19     <refname>sd_bus_message_get_type</refname>
  20     <refname>sd_bus_message_is_signal</refname>
  21     <refname>sd_bus_message_is_method_call</refname>
  22     <refname>sd_bus_message_is_method_error</refname>
  23
  24     <refpurpose>Query bus message addressing metadata</refpurpose>
  25   </refnamediv>
  26
  27   <refsynopsisdiv>
  28     <funcsynopsis>
  29       <funcsynopsisinfo>#include &lt;systemd/sd-bus.h&gt;</funcsynopsisinfo>
  30
  31       <funcprototype>
  32         <funcdef>int <function>sd_bus_message_get_type</function></funcdef>
  33         <paramdef>sd_bus_message *<parameter>message</parameter></paramdef>
  34         <paramdef>uint8_t *<parameter>type</parameter></paramdef>
  35       </funcprototype>
  36
  37       <funcprototype>
  38         <funcdef>int <function>sd_bus_message_is_signal</function></funcdef>
  39         <paramdef>sd_bus_message *<parameter>message</parameter></paramdef>
  40         <paramdef>const char *<parameter>interface</parameter></paramdef>
  41         <paramdef>const char *<parameter>member</parameter></paramdef>
  42       </funcprototype>
  43
  44       <funcprototype>
  45         <funcdef>int <function>sd_bus_message_is_method_call</function></funcdef>
  46         <paramdef>sd_bus_message *<parameter>message</parameter></paramdef>
  47         <paramdef>const char *<parameter>interface</parameter></paramdef>
  48         <paramdef>const char *<parameter>member</parameter></paramdef>
  49       </funcprototype>
  50
  51       <funcprototype>
  52         <funcdef>int <function>sd_bus_message_is_method_error</function></funcdef>
  53         <paramdef>sd_bus_message *<parameter>message</parameter></paramdef>
  54         <paramdef>const char *<parameter>name</parameter></paramdef>
  55       </funcprototype>
  56     </funcsynopsis>
  57
  58   </refsynopsisdiv>
  59
  60   <refsect1>
  61     <title>Description</title>
  62
  63     <para><function>sd_bus_message_get_type()</function> returns the type of a message in the output
  64     parameter <parameter>type</parameter>, one of <constant>SD_BUS_MESSAGE_METHOD_CALL</constant>,
  65     <constant>SD_BUS_MESSAGE_METHOD_RETURN</constant>,
  66     <constant>SD_BUS_MESSAGE_METHOD_ERROR</constant>, <constant>SD_BUS_MESSAGE_SIGNAL</constant>.
  67     This type is either specified as a parameter when the message is created using
  68     <citerefentry><refentrytitle>sd_bus_set_message_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
  69     or is set automatically when the message is created using
  70     <citerefentry><refentrytitle>sd_bus_set_message_new_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
  71     <citerefentry><refentrytitle>sd_bus_set_message_new_method_call</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
  72     <citerefentry><refentrytitle>sd_bus_set_message_new_method_error</refentrytitle><manvolnum>3</manvolnum></citerefentry>
  73     and similar functions.
  74     </para>
  75
  76     <para><function>sd_bus_message_is_signal()</function> checks if message <parameter>m</parameter>
  77     is a signal message. If <parameter>interface</parameter> is non-null, it also checks if the
  78     message has the same interface set. If <parameter>member</parameter> is non-null, it also checks
  79     if the message has the same member set. Also see
  80     <citerefentry><refentrytitle>sd_bus_set_message_new_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>. It returns true when all checks pass.</para>
  81
  82     <para><function>sd_bus_message_is_method_call()</function> checks if message <parameter>m</parameter>
  83     is a method call message. If <parameter>interface</parameter> is non-null, it also checks if the
  84     message has the same interface set. If <parameter>member</parameter> is non-null, it also checks
  85     if the message has the same member set. Also see
  86     <citerefentry><refentrytitle>sd_bus_set_message_new_method_call</refentrytitle><manvolnum>3</manvolnum></citerefentry>. It returns true when all checks pass.</para>
  87
  88     <para><function>sd_bus_message_is_method_error()</function> checks if message <parameter>m</parameter>
  89     is an error reply message. If <parameter>name</parameter> is non-null, it also checks if the
  90     message has the same error identifier set. Also see
  91     <citerefentry><refentrytitle>sd_bus_set_message_new_method_error</refentrytitle><manvolnum>3</manvolnum></citerefentry>. It returns true when all checks pass.</para>
  92 </refsect1>
  93
  94   <refsect1>
  95     <title>Return Value</title>
  96
  97     <para>On success, those functions return 0 or a positive
  98     integer. On failure, it returns a negative errno-style error code.</para>
  99
 100     <refsect2>
 101       <title>Errors</title>
 102
 103       <para>Returned errors may indicate the following problems:</para>
 104
 105       <variablelist>
 106         <varlistentry>
 107           <term><constant>-EINVAL</constant></term>
 108
 109           <listitem><para>The <parameter>message</parameter> parameter or the output parameter are
 110           <constant>NULL</constant>.</para></listitem>
 111         </varlistentry>
 112       </variablelist>
 113     </refsect2>
 114   </refsect1>
 115
 116   <xi:include href="libsystemd-pkgconfig.xml" />
 117
 118   <refsect1>
 119     <title>See Also</title>
 120
 121     <para>
 122       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 123       <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 124       <citerefentry><refentrytitle>sd_bus_message_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 125       <citerefentry><refentrytitle>sd_bus_message_set_destination</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 126     </para>
 127   </refsect1>
 128
 129 </refentry>