diff options
Diffstat (limited to 'man/sd_bus_message_new.xml')
| -rw-r--r-- | man/sd_bus_message_new.xml | 189 |
1 files changed, 189 insertions, 0 deletions
diff --git a/man/sd_bus_message_new.xml b/man/sd_bus_message_new.xml new file mode 100644 index 0000000..4907c5a --- /dev/null +++ b/man/sd_bus_message_new.xml @@ -0,0 +1,189 @@ +<?xml version='1.0'?> +<!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_new" xmlns:xi="http://www.w3.org/2001/XInclude"> + <refentryinfo> + <title>sd_bus_message_new</title> + <productname>systemd</productname> + </refentryinfo> + + <refmeta> + <refentrytitle>sd_bus_message_new</refentrytitle> + <manvolnum>3</manvolnum> + </refmeta> + + <refnamediv> + <refname>sd_bus_message_new</refname> + <refname>sd_bus_message_ref</refname> + <refname>sd_bus_message_unref</refname> + <refname>sd_bus_message_unrefp</refname> + <refname>SD_BUS_MESSAGE_METHOD_CALL</refname> + <refname>SD_BUS_MESSAGE_METHOD_RETURN</refname> + <refname>SD_BUS_MESSAGE_METHOD_ERROR</refname> + <refname>SD_BUS_MESSAGE_SIGNAL</refname> + <refname>sd_bus_message_get_bus</refname> + + <refpurpose>Create a new bus message object and create or destroy references to it</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo> + + <funcsynopsisinfo><token>enum</token> { + <constant>SD_BUS_MESSAGE_METHOD_CALL</constant>, + <constant>SD_BUS_MESSAGE_METHOD_RETURN</constant>, + <constant>SD_BUS_MESSAGE_METHOD_ERROR</constant>, + <constant>SD_BUS_MESSAGE_SIGNAL</constant>, +};</funcsynopsisinfo> + + <funcprototype> + <funcdef>int <function>sd_bus_message_new</function></funcdef> + <paramdef>sd_bus *<parameter>bus</parameter></paramdef> + <paramdef>sd_bus_message **<parameter>m</parameter></paramdef> + <paramdef>uint8_t <parameter>type</parameter></paramdef> + </funcprototype> + + <funcprototype> + <funcdef>sd_bus_message *<function>sd_bus_message_ref</function></funcdef> + <paramdef>sd_bus_message *<parameter>m</parameter></paramdef> + </funcprototype> + + <funcprototype> + <funcdef>sd_bus_message *<function>sd_bus_message_unref</function></funcdef> + <paramdef>sd_bus_message *<parameter>m</parameter></paramdef> + </funcprototype> + + <funcprototype> + <funcdef>void <function>sd_bus_message_unrefp</function></funcdef> + <paramdef>sd_bus_message **<parameter>mp</parameter></paramdef> + </funcprototype> + + <funcprototype> + <funcdef>sd_bus *<function>sd_bus_message_get_bus</function></funcdef> + <paramdef>sd_bus_message *<parameter>m</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Description</title> + + <para><function>sd_bus_message_new()</function> creates a new bus message object attached to the + bus <parameter>bus</parameter> and returns it in the output parameter <parameter>m</parameter>. + This object is reference-counted, and will be destroyed when all references are gone. Initially, + the caller of this function owns the sole reference to the message object. Note that the message + object holds a reference to the bus object, so the bus object will not be destroyed as long as + the message exists.</para> + + <para>Note: this is a low-level call. In most cases functions like + <citerefentry><refentrytitle>sd_bus_message_new_method_call</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry><refentrytitle>sd_bus_message_new_method_error</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry><refentrytitle>sd_bus_message_new_method_return</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + and <citerefentry><refentrytitle>sd_bus_message_new_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry> + that create a message of a certain type and initialize various fields are easier to use.</para> + + <para>The <parameter>type</parameter> parameter specifies the type of the message. It must be + one of <constant>SD_BUS_MESSAGE_METHOD_CALL</constant> — a method call, + <constant>SD_BUS_MESSAGE_METHOD_RETURN</constant> — a method call reply, + <constant>SD_BUS_MESSAGE_METHOD_ERROR</constant> — an error reply to a method call, + <constant>SD_BUS_MESSAGE_SIGNAL</constant> — a broadcast message with no reply. + </para> + + <para>The flag to allow interactive authorization is initialized based on the current value set + in the bus object, see + <citerefentry><refentrytitle>sd_bus_set_allow_interactive_authorization</refentrytitle><manvolnum>3</manvolnum></citerefentry>. + This may be changed using + <citerefentry><refentrytitle>sd_bus_message_set_allow_interactive_authorization</refentrytitle><manvolnum>3</manvolnum></citerefentry>. + </para> + + <para><function>sd_bus_message_ref()</function> increases the reference counter of + <parameter>m</parameter> by one.</para> + + <para><function>sd_bus_message_unref()</function> decreases the reference counter of + <parameter>m</parameter> by one. Once the reference count has dropped to zero, message object is + destroyed and cannot be used anymore, so further calls to + <function>sd_bus_message_ref()</function> or <function>sd_bus_message_unref()</function> are + illegal.</para> + + <para><function>sd_bus_message_unrefp()</function> is similar to + <function>sd_bus_message_unref()</function> but takes a pointer to a + pointer to an <type>sd_bus_message</type> object. This call is useful in + conjunction with GCC's and LLVM's <ulink + url="https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html">Clean-up + Variable Attribute</ulink>. See + <citerefentry><refentrytitle>sd_bus_new</refentrytitle><manvolnum>3</manvolnum></citerefentry> + for an example how to use the cleanup attribute.</para> + + <para><function>sd_bus_message_ref()</function> and <function>sd_bus_message_unref()</function> + execute no operation if the passed in bus message object address is + <constant>NULL</constant>. <function>sd_bus_message_unrefp()</function> will first dereference + its argument, which must not be <constant>NULL</constant>, and will execute no operation if + <emphasis>that</emphasis> is <constant>NULL</constant>. + </para> + + <para><function>sd_bus_message_get_bus()</function> returns the bus object that message + <parameter>m</parameter> is attached to.</para> + </refsect1> + + <refsect1> + <title>Return Value</title> + + <para>On success, <function>sd_bus_message_new()</function> returns 0 or a positive integer. On + failure, it returns a negative errno-style error code.</para> + + <para><function>sd_bus_message_ref()</function> always returns the argument. + </para> + + <para><function>sd_bus_message_unref()</function> always returns + <constant>NULL</constant>.</para> + + <para><function>sd_bus_message_get_bus()</function> always returns the bus object.</para> + + <refsect2> + <title>Errors</title> + + <para>Returned errors may indicate the following problems:</para> + + <variablelist> + <varlistentry> + <term><constant>-EINVAL</constant></term> + + <listitem><para>Specified <parameter>type</parameter> is invalid.</para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>-ENOTCONN</constant></term> + + <listitem><para>The bus parameter <parameter>bus</parameter> is <constant>NULL</constant> or + the bus is not connected.</para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>-ENOMEM</constant></term> + + <listitem><para>Memory allocation failed.</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_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry><refentrytitle>sd_bus_message_new_method_call</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry><refentrytitle>sd_bus_message_new_method_error</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry><refentrytitle>sd_bus_message_new_method_return</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry><refentrytitle>sd_bus_message_new_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry> + </para> + </refsect1> + +</refentry> |