diff options
Diffstat (limited to 'src/libsystemd/sd_bus_message_append_array.xml')
| -rw-r--r-- | src/libsystemd/sd_bus_message_append_array.xml | 213 |
1 files changed, 213 insertions, 0 deletions
diff --git a/src/libsystemd/sd_bus_message_append_array.xml b/src/libsystemd/sd_bus_message_append_array.xml new file mode 100644 index 0000000000..27db2a96c3 --- /dev/null +++ b/src/libsystemd/sd_bus_message_append_array.xml @@ -0,0 +1,213 @@ +<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*--> +<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" +"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> + +<!-- + This file is part of systemd. + + Copyright 2014 Zbigniew Jędrzejewski-Szmek + + systemd is free software; you can redistribute it and/or modify it + under the terms of the GNU Lesser General Public License as published by + the Free Software Foundation; either version 2.1 of the License, or + (at your option) any later version. + + systemd is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public License + along with systemd; If not, see <http://www.gnu.org/licenses/>. +--> + +<refentry id="sd_bus_message_append_array" + xmlns:xi="http://www.w3.org/2001/XInclude"> + + <refentryinfo> + <title>sd_bus_message_append_array</title> + <productname>systemd</productname> + + <authorgroup> + <author> + <contrib>A monkey with a typewriter</contrib> + <firstname>Zbigniew</firstname> + <surname>Jędrzejewski-Szmek</surname> + <email>zbyszek@in.waw.pl</email> + </author> + </authorgroup> + </refentryinfo> + + <refmeta> + <refentrytitle>sd_bus_message_append_array</refentrytitle> + <manvolnum>3</manvolnum> + </refmeta> + + <refnamediv> + <refname>sd_bus_message_append_array</refname> + <refname>sd_bus_message_append_array_memfd</refname> + <refname>sd_bus_message_append_array_iovec</refname> + <refname>sd_bus_message_append_array_space</refname> + + <refpurpose>Append an array of fields to a D-Bus + message</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo> + + <funcprototype> + <funcdef>int sd_bus_message_append_array</funcdef> + <paramdef>sd_bus_message *<parameter>m</parameter></paramdef> + <paramdef>char <parameter>type</parameter></paramdef> + <paramdef>char void *<parameter>ptr</parameter></paramdef> + <paramdef>size_t <parameter>size</parameter></paramdef> + </funcprototype> + + <funcprototype> + <funcdef>int sd_bus_message_append_array_memfd</funcdef> + <paramdef>sd_bus_message *<parameter>m</parameter></paramdef> + <paramdef>char <parameter>type</parameter></paramdef> + <paramdef>int <parameter>memfd</parameter></paramdef> + <paramdef>uint64_t <parameter>offset</parameter></paramdef> + <paramdef>uint64_t <parameter>size</parameter></paramdef> + </funcprototype> + + <funcprototype> + <funcdef>int sd_bus_message_append_array_iovec</funcdef> + <paramdef>sd_bus_message *<parameter>m</parameter></paramdef> + <paramdef>char <parameter>type</parameter></paramdef> + <paramdef>const struct iovec *<parameter>iov</parameter></paramdef> + <paramdef>unsigned <parameter>n</parameter></paramdef> + </funcprototype> + + <funcprototype> + <funcdef>int sd_bus_message_append_array_space</funcdef> + <paramdef>char <parameter>type</parameter></paramdef> + <paramdef>size_t <parameter>size</parameter></paramdef> + <paramdef>void **<parameter>ptr</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Description</title> + + <para>The <function>sd_bus_message_append_array()</function> + function appends an array to a D-Bus message + <parameter>m</parameter>. A container will be opened, the array + contents appended, and the container closed. The parameter + <parameter>type</parameter> determines how the pointer + <parameter>p</parameter> is interpreted. + <parameter>type</parameter> must be one of the "trivial" types + <literal>y</literal>, <literal>n</literal>, <literal>q</literal>, + <literal>i</literal>, <literal>u</literal>, <literal>x</literal>, + <literal>t</literal>, <literal>d</literal> (but not + <literal>b</literal>), as defined by the <ulink + url="http://dbus.freedesktop.org/doc/dbus-specification.html#basic-types">Basic + Types</ulink> section of the D-Bus specification, and listed in + <citerefentry><refentrytitle>sd_bus_message_append_basic</refentrytitle><manvolnum>3</manvolnum></citerefentry>. + Pointer <parameter>p</parameter> must point to an array of size + <parameter>size</parameter> bytes containing items of the + respective type. Size <parameter>size</parameter> must be a + multiple of the size of the type <parameter>type</parameter>. As a + special case, <parameter>p</parameter> may be + <constant>NULL</constant>, if <parameter>size</parameter> is 0. + The memory pointed to by <parameter>p</parameter> is copied into + the memory area containing the message and stays in possession of + the caller. The caller may hence freely change the data after this + call without affecting the message the array was appended + to.</para> + + <para>The <function>sd_bus_message_append_array_memfd()</function> + function appends an array of a trivial type to message + <parameter>m</parameter>, similar to + <function>sd_bus_message_append_array()</function>. The contents + of the memory file descriptor <parameter>memfd</parameter> + starting at the specified offset and of the specified size is + used as the contents of the array. The offset and size must be a + multiple of the size of the type + <parameter>type</parameter>. However, as a special exception, if + the offset is specified as zero and the size specified as + UINT64_MAX the full memory file descriptor contents is used. The + memory file descriptor is sealed by this call if it has not been + sealed yet, and cannot be modified after this call. See + <citerefentry + project='man-pages'><refentrytitle>memfd_create</refentrytitle><manvolnum>2</manvolnum></citerefentry> + for details about memory file descriptors. Appending arrays with + memory file descriptors enables efficient zero-copy data transfer, + as the memory file descriptor may be passed as-is to the + destination, without copying the memory in it to the destination + process. Not all protocol transports support passing memory file + descriptors between participants, in which case this call will + automatically fall back to copying. Also, as memory file + descriptor passing is inefficient for smaller amounts of data, + copying might still be enforced even where memory file descriptor + passing is supported.</para> + + <para>The <function>sd_bus_message_append_array_iovec()</function> + function appends an array of a trivial type to the message + <parameter>m</parameter>, similar to + <function>sd_bus_message_append_array()</function>. Contents of + the I/O vector array <parameter>iov</parameter> are used as the + contents of the array. The total size of + <parameter>iov</parameter> payload (the sum of + <structfield>iov_len</structfield> fields) must be a multiple of + the size of the type <parameter>type</parameter>. The + <parameter>iov</parameter> argument must point to + <parameter>n</parameter> I/O vector 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 (set to zero), in which case a block of zeros of length + <structname>iov_len</structname> bytes 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_array_space()</function> + function appends space for an array of a trivial type to message + <parameter>m</parameter>. It behaves the same as + <function>sd_bus_message_append_array()</function>, but instead of + copying items to the message, it returns a pointer to the + destination area to the caller in pointer + <parameter>p</parameter>. The caller should subsequently write the + array contents to this memory. Modifications to the memory + pointed to should only occur until the next operation on the bus + message is invoked. Most importantly, the memory should not be + altered anymore when another field has been added to the message + or the message has been sealed.</para> + </refsect1> + + <refsect1> + <title>Return Value</title> + + <para>On success, these calls return 0 or a positive integer. On + failure, they return a negative errno-style error code.</para> + </refsect1> + + <xi:include href="sd_bus_message_append_basic.xml" xpointer="errors" /> + + <refsect1> + <title>Notes</title> + + <para><function>sd_bus_append_array()</function> and other + functions described here are available as a shared library, which + can be compiled and linked to with the + <constant>libsystemd</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry> + file.</para> + </refsect1> + + <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>, + <citerefentry><refentrytitle>sd_bus_message_append_basic</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry project='man-pages'><refentrytitle>memfd_create</refentrytitle><manvolnum>2</manvolnum></citerefentry>, + <ulink url="http://dbus.freedesktop.org/doc/dbus-specification.html">The D-Bus specification</ulink> + </para> + </refsect1> + +</refentry> |