man/sd_bus_message_append_string_memfd.xml

   1 <?xml version='1.0'?>
   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-or-later -->
   5
   6 <refentry id="sd_bus_message_append_string_memfd"
   7           xmlns:xi="http://www.w3.org/2001/XInclude">
   8
   9   <refentryinfo>
  10     <title>sd_bus_message_append_string_memfd</title>
  11     <productname>systemd</productname>
  12   </refentryinfo>
  13
  14   <refmeta>
  15     <refentrytitle>sd_bus_message_append_string_memfd</refentrytitle>
  16     <manvolnum>3</manvolnum>
  17   </refmeta>
  18
  19   <refnamediv>
  20     <refname>sd_bus_message_append_string_memfd</refname>
  21     <refname>sd_bus_message_append_string_iovec</refname>
  22     <refname>sd_bus_message_append_string_space</refname>
  23
  24     <refpurpose>Attach a string to a message</refpurpose>
  25   </refnamediv>
  26
  27   <refsynopsisdiv>
  28     <funcsynopsis>
  29       <funcsynopsisinfo>#include &lt;systemd/sd-bus.h&gt;</funcsynopsisinfo>
  30
  31       <funcprototype>
  32         <funcdef>int sd_bus_message_append_string_memfd</funcdef>
  33         <paramdef>sd_bus_message *<parameter>m</parameter></paramdef>
  34         <paramdef>int <parameter>memfd</parameter></paramdef>
  35       </funcprototype>
  36
  37       <funcprototype>
  38         <funcdef>int sd_bus_message_append_string_iovec</funcdef>
  39         <paramdef>sd_bus_message *<parameter>m</parameter></paramdef>
  40         <paramdef>const struct iovec *<parameter>iov</parameter></paramdef>
  41         <paramdef>unsigned <parameter>n</parameter></paramdef>
  42       </funcprototype>
  43
  44       <funcprototype>
  45         <funcdef>int sd_bus_message_append_string_space</funcdef>
  46         <paramdef>sd_bus_message *<parameter>m</parameter></paramdef>
  47         <paramdef>size_t <parameter>size</parameter></paramdef>
  48         <paramdef>char **<parameter>s</parameter></paramdef>
  49       </funcprototype>
  50     </funcsynopsis>
  51   </refsynopsisdiv>
  52
  53   <refsect1>
  54     <title>Description</title>
  55
  56     <para>The functions
  57     <function>sd_bus_message_append_string_memfd()</function> and
  58     <function>sd_bus_message_append_string_iovec()</function> can be
  59     used to append a single string (item of type <literal>s</literal>)
  60     to message <parameter>m</parameter>.</para>
  61
  62     <para>In case of
  63     <function>sd_bus_message_append_string_memfd()</function>, the
  64     contents of <parameter>memfd</parameter> are the string. They must
  65     satisfy the same constraints as described for the
  66     <literal>s</literal> type in
  67     <citerefentry><refentrytitle>sd_bus_message_append_basic</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
  68
  69     <para>In case of
  70     <function>sd_bus_message_append_string_iovec()</function>, the
  71     payload of <parameter>iov</parameter> is the string. It must
  72     satisfy the same constraints as described for the
  73     <literal>s</literal> type in
  74     <citerefentry><refentrytitle>sd_bus_message_append_basic</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
  75
  76     <para>The <parameter>iov</parameter> argument must point to
  77     <parameter>n</parameter> <structname>struct iovec</structname>
  78     structures. Each structure may have the
  79     <structname>iov_base</structname> field set, in which case the
  80     memory pointed to will be copied into the message, or unset, in
  81     which case a block of spaces (ASCII 32) of length
  82     <structname>iov_len</structname> will be inserted. The
  83     memory pointed at by <parameter>iov</parameter> may be changed
  84     after this call.</para>
  85
  86     <para>The
  87     <function>sd_bus_message_append_string_space()</function> function appends
  88     space for a string to message <parameter>m</parameter>. It behaves
  89     similar to <function>sd_bus_message_append_basic()</function> with
  90     type <literal>s</literal>, but instead of copying a string into
  91     the message, it returns a pointer to the destination area to
  92     the caller in pointer <parameter>p</parameter>. Space for the string
  93     of length <parameter>size</parameter> plus the terminating
  94     <constant>NUL</constant> is allocated.</para>
  95   </refsect1>
  96
  97   <refsect1>
  98     <title>Return Value</title>
  99
 100     <para>On success, those calls return 0 or a positive integer. On failure, they return a negative
 101     errno-style error code.</para>
 102
 103     <xi:include href="sd_bus_message_append_basic.xml" xpointer="errors" />
 104   </refsect1>
 105
 106   <xi:include href="libsystemd-pkgconfig.xml" />
 107
 108   <refsect1>
 109     <title>See Also</title>
 110
 111     <para>
 112       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 113       <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 114       <citerefentry><refentrytitle>sd_bus_message_append_basic</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 115       <ulink url="https://dbus.freedesktop.org/doc/dbus-specification.html">The D-Bus specification</ulink>
 116     </para>
 117   </refsect1>
 118
 119 </refentry>