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+<?xml version='1.0'?> <!--*-nxml-*-->
+<!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 2010 Lennart Poettering
+
+ 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_is_fifo">
+
+ <refentryinfo>
+ <title>sd_is_fifo</title>
+ <productname>systemd</productname>
+
+ <authorgroup>
+ <author>
+ <contrib>Developer</contrib>
+ <firstname>Lennart</firstname>
+ <surname>Poettering</surname>
+ <email>lennart@poettering.net</email>
+ </author>
+ </authorgroup>
+ </refentryinfo>
+
+ <refmeta>
+ <refentrytitle>sd_is_fifo</refentrytitle>
+ <manvolnum>3</manvolnum>
+ </refmeta>
+
+ <refnamediv>
+ <refname>sd_is_fifo</refname>
+ <refname>sd_is_socket</refname>
+ <refname>sd_is_socket_inet</refname>
+ <refname>sd_is_socket_unix</refname>
+ <refname>sd_is_mq</refname>
+ <refpurpose>Check the type of a file descriptor</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+ <funcsynopsis>
+ <funcsynopsisinfo>#include &lt;systemd/sd-daemon.h&gt;</funcsynopsisinfo>
+
+ <funcprototype>
+ <funcdef>int <function>sd_is_fifo</function></funcdef>
+ <paramdef>int <parameter>fd</parameter></paramdef>
+ <paramdef>const char *<parameter>path</parameter></paramdef>
+ </funcprototype>
+
+ <funcprototype>
+ <funcdef>int <function>sd_is_socket</function></funcdef>
+ <paramdef>int <parameter>fd</parameter></paramdef>
+ <paramdef>int <parameter>family</parameter></paramdef>
+ <paramdef>int <parameter>type</parameter></paramdef>
+ <paramdef>int <parameter>listening</parameter></paramdef>
+ </funcprototype>
+
+ <funcprototype>
+ <funcdef>int <function>sd_is_socket_inet</function></funcdef>
+ <paramdef>int <parameter>fd</parameter></paramdef>
+ <paramdef>int <parameter>family</parameter></paramdef>
+ <paramdef>int <parameter>type</parameter></paramdef>
+ <paramdef>int <parameter>listening</parameter></paramdef>
+ <paramdef>uint16_t <parameter>port</parameter></paramdef>
+ </funcprototype>
+
+ <funcprototype>
+ <funcdef>int <function>sd_is_socket_unix</function></funcdef>
+ <paramdef>int <parameter>fd</parameter></paramdef>
+ <paramdef>int <parameter>type</parameter></paramdef>
+ <paramdef>int <parameter>listening</parameter></paramdef>
+ <paramdef>const char* <parameter>path</parameter></paramdef>
+ <paramdef>size_t <parameter>length</parameter></paramdef>
+ </funcprototype>
+
+ <funcprototype>
+ <funcdef>int <function>sd_is_mq</function></funcdef>
+ <paramdef>int <parameter>fd</parameter></paramdef>
+ <paramdef>const char *<parameter>path</parameter></paramdef>
+ </funcprototype>
+
+ </funcsynopsis>
+ </refsynopsisdiv>
+
+ <refsect1>
+ <title>Description</title>
+
+ <para><function>sd_is_fifo()</function> may be called
+ to check whether the specified file descriptor refers
+ to a FIFO or pipe. If the <parameter>path</parameter>
+ parameter is not NULL, it is checked whether the FIFO
+ is bound to the specified file system path.</para>
+
+ <para><function>sd_is_socket()</function> may be
+ called to check whether the specified file descriptor
+ refers to a socket. If the
+ <parameter>family</parameter> parameter is not
+ AF_UNSPEC it is checked whether the socket is of the
+ specified family (AF_UNIX, AF_INET, ...). If the
+ <parameter>type</parameter> parameter is not 0 it is
+ checked whether the socket is of the specified type
+ (SOCK_STREAM, SOCK_DGRAM, ...). If the
+ <parameter>listening</parameter> parameter is positive
+ it is checked whether the socket is in accepting mode,
+ i.e. <function>listen()</function> has been called for
+ it. If <parameter>listening</parameter> is 0, it is
+ checked whether the socket is not in this mode. If the
+ parameter is negative, no such check is made. The
+ <parameter>listening</parameter> parameter should only
+ be used for stream sockets and should be set to a
+ negative value otherwise.</para>
+
+ <para><function>sd_is_socket_inet()</function> is
+ similar to <function>sd_is_socket()</function>, but
+ optionally checks the IPv4 or IPv6 port number the
+ socket is bound to, unless <parameter>port</parameter>
+ is zero. For this call <parameter>family</parameter>
+ must be passed as either AF_UNSPEC, AF_INET, or
+ AF_INET6.</para>
+
+ <para><function>sd_is_socket_unix()</function> is
+ similar to <function>sd_is_socket()</function>, but
+ optionally checks the AF_UNIX path the socket is bound
+ to, unless the <parameter>path</parameter> parameter
+ is NULL. For normal file system AF_UNIX sockets set
+ the <parameter>length</parameter> parameter to 0. For
+ Linux abstract namespace sockets set the
+ <parameter>length</parameter> to the size of the
+ address, including the initial 0 byte and set
+ <parameter>path</parameter> to the initial 0 byte of
+ the socket address.</para>
+
+ <para><function>sd_is_mq()</function> may be called to
+ check whether the specified file descriptor refers to
+ a POSIX message queue. If the
+ <parameter>path</parameter> parameter is not NULL, it
+ is checked whether the message queue is bound to the
+ specified name.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>Return Value</title>
+
+ <para>On failure, these calls return a negative
+ errno-style error code. If the file descriptor is of
+ the specified type and bound to the specified address
+ a positive return value is returned, otherwise
+ zero.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>Notes</title>
+
+ <para>These functions are provided by the reference
+ implementation of APIs for new-style daemons and
+ distributed with the systemd package. The algorithms
+ they implement are simple, and can easily be
+ reimplemented in daemons if it is important to support
+ this interface without using the reference
+ implementation.</para>
+
+ <para>Internally, these function use a combination of
+ <filename>fstat()</filename> and
+ <filename>getsockname()</filename> to check the file
+ descriptor type and where it is bound to.</para>
+
+ <para>For details about the algorithms check the
+ liberally licensed reference implementation sources:
+ <ulink url="http://cgit.freedesktop.org/systemd/systemd/plain/src/libsystemd-daemon/sd-daemon.c"/>
+ and <ulink
+ url="http://cgit.freedesktop.org/systemd/systemd/plain/src/systemd/sd-daemon.h"/></para>
+
+ <para><function>sd_is_fifo()</function> and the
+ related functions are implemented in the reference
+ implementation's <filename>sd-daemon.c</filename> and
+ <filename>sd-daemon.h</filename> files. These
+ interfaces are available as shared library, which can
+ be compiled and linked to with the
+ <literal>libsystemd-daemon</literal>
+ <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+ file. Alternatively, applications consuming these APIs
+ may copy the implementation into their source
+ tree. For more details about the reference
+ implementation see
+ <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
+
+ <para>These functions continue to work as described,
+ even if -DDISABLE_SYSTEMD is set during
+ compilation.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>See Also</title>
+ <para>
+ <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ </para>
+ </refsect1>
+
+</refentry>