<?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_append_string_memfd" xmlns:xi="http://www.w3.org/2001/XInclude"> <refentryinfo> <title>sd_bus_message_append_string_memfd</title> <productname>systemd</productname> </refentryinfo> <refmeta> <refentrytitle>sd_bus_message_append_string_memfd</refentrytitle> <manvolnum>3</manvolnum> </refmeta> <refnamediv> <refname>sd_bus_message_append_string_memfd</refname> <refname>sd_bus_message_append_string_iovec</refname> <refname>sd_bus_message_append_string_space</refname> <refpurpose>Attach a string to a message</refpurpose> </refnamediv> <refsynopsisdiv> <funcsynopsis> <funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo> <funcprototype> <funcdef>int sd_bus_message_append_string_memfd</funcdef> <paramdef>sd_bus_message *<parameter>m</parameter></paramdef> <paramdef>int <parameter>memfd</parameter></paramdef> </funcprototype> <funcprototype> <funcdef>int sd_bus_message_append_string_iovec</funcdef> <paramdef>sd_bus_message *<parameter>m</parameter></paramdef> <paramdef>const struct iovec *<parameter>iov</parameter></paramdef> <paramdef>unsigned <parameter>n</parameter></paramdef> </funcprototype> <funcprototype> <funcdef>int sd_bus_message_append_string_space</funcdef> <paramdef>sd_bus_message *<parameter>m</parameter></paramdef> <paramdef>size_t <parameter>size</parameter></paramdef> <paramdef>char **<parameter>s</parameter></paramdef> </funcprototype> </funcsynopsis> </refsynopsisdiv> <refsect1> <title>Description</title> <para>The functions <function>sd_bus_message_append_string_memfd()</function> and <function>sd_bus_message_append_string_iovec()</function> can be used to append a single string (item of type <literal>s</literal>) to message <parameter>m</parameter>.</para> <para>In case of <function>sd_bus_message_append_string_memfd()</function>, the contents of <parameter>memfd</parameter> are the string. They must satisfy the same constraints as described for the <literal>s</literal> type in <citerefentry><refentrytitle>sd_bus_message_append_basic</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para> <para>In case of <function>sd_bus_message_append_string_iovec()</function>, the payload of <parameter>iov</parameter> is the string. It must satisfy the same constraints as described for the <literal>s</literal> type in <citerefentry><refentrytitle>sd_bus_message_append_basic</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para> <para>The <parameter>iov</parameter> argument must point to <parameter>n</parameter> <structname>struct iovec</structname> structures. Each structure may have the <structname>iov_base</structname> field set, in which case the memory pointed to will be copied into the message, or unset, in which case a block of spaces (ASCII 32) of length <structname>iov_len</structname> will be inserted. The memory pointed at by <parameter>iov</parameter> may be changed after this call.</para> <para>The <function>sd_bus_message_append_string_space()</function> function appends space for a string to message <parameter>m</parameter>. It behaves similar to <function>sd_bus_message_append_basic()</function> with type <literal>s</literal>, but instead of copying a string into the message, it returns a pointer to the destination area to the caller in pointer <parameter>p</parameter>. Space for the string of length <parameter>size</parameter> plus the terminating <constant>NUL</constant> is allocated.</para> </refsect1> <refsect1> <title>Return Value</title> <para>On success, those calls return 0 or a positive integer. On failure, they return a negative errno-style error code.</para> <xi:include href="sd_bus_message_append_basic.xml" xpointer="errors" /> </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_basic</refentrytitle><manvolnum>3</manvolnum></citerefentry>, <ulink url="https://dbus.freedesktop.org/doc/dbus-specification.html">The D-Bus specification</ulink> </para> </refsect1> </refentry>