systemd/man/sd_is_fifo.xml
Lennart Poettering 818bf54632 tree-wide: drop 'This file is part of systemd' blurb
This part of the copyright blurb stems from the GPL use recommendations:

https://www.gnu.org/licenses/gpl-howto.en.html

The concept appears to originate in times where version control was per
file, instead of per tree, and was a way to glue the files together.
Ultimately, we nowadays don't live in that world anymore, and this
information is entirely useless anyway, as people are very welcome to
copy these files into any projects they like, and they shouldn't have to
change bits that are part of our copyright header for that.

hence, let's just get rid of this old cruft, and shorten our codebase a
bit.
2018-06-14 10:20:20 +02:00

216 lines
9.4 KiB
XML

<?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">
<!--
SPDX-License-Identifier: LGPL-2.1+
Copyright 2010 Lennart Poettering
-->
<refentry id="sd_is_fifo"
xmlns:xi="http://www.w3.org/2001/XInclude">
<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_socket_sockaddr</refname>
<refname>sd_is_mq</refname>
<refname>sd_is_special</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_sockaddr</function></funcdef>
<paramdef>int <parameter>fd</parameter></paramdef>
<paramdef>int <parameter>type</parameter></paramdef>
<paramdef>const struct sockaddr *<parameter>addr</parameter></paramdef>
<paramdef>unsigned <parameter>addr_len</parameter></paramdef>
<paramdef>int <parameter>listening</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>
<funcprototype>
<funcdef>int <function>sd_is_special</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
<constant>NULL</constant>, 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
<constant>AF_UNSPEC</constant>, it is checked whether the socket
is of the specified family (<constant>AF_UNIX</constant>,
<constant>AF_INET</constant>, …). If the <parameter>type</parameter>
parameter is not 0, it is checked whether the socket is of the
specified type (<constant>SOCK_STREAM</constant>,
<constant>SOCK_DGRAM</constant>, …). 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
<constant>AF_UNSPEC</constant>, <constant>AF_INET</constant>, or
<constant>AF_INET6</constant>.</para>
<para><function>sd_is_socket_sockaddr()</function> is similar to
<function>sd_is_socket_inet()</function>, but checks if the socket is bound to the
address specified by <parameter>addr</parameter>. The
<structfield>family</structfield> specified by <parameter>addr</parameter> must be
either <constant>AF_INET</constant> or <constant>AF_INET6</constant> and
<parameter>addr_len</parameter> must be large enough for that family. If
<parameter>addr</parameter> specifies a non-zero port, it is also checked if the
socket is bound to this port. In addition, for IPv6, if <parameter>addr</parameter>
specifies non-zero <structfield>sin6_flowinfo</structfield> or
<structfield>sin6_scope_id</structfield>, it is checked if the socket has the same
values.</para>
<para><function>sd_is_socket_unix()</function> is similar to
<function>sd_is_socket()</function> but optionally checks the
<constant>AF_UNIX</constant> path the socket is bound to, unless
the <parameter>path</parameter> parameter is
<constant>NULL</constant>. For normal file system
<constant>AF_UNIX</constant> 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 the
<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
<constant>NULL</constant>, it is checked whether the message queue
is bound to the specified name.</para>
<para><function>sd_is_special()</function> may be called to check
whether the specified file descriptor refers to a special file. If
the <parameter>path</parameter> parameter is not
<constant>NULL</constant>, it is checked whether the file
descriptor is bound to the specified filename. Special files in
this context are character device nodes and files in
<filename>/proc</filename> or <filename>/sys</filename>.</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>
<xi:include href="libsystemd-pkgconfig.xml" xpointer="pkgconfig-text"/>
<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>
</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>,
<citerefentry project='man-pages'><refentrytitle>ip</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
<citerefentry project='man-pages'><refentrytitle>ipv6</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
<citerefentry project='man-pages'><refentrytitle>unix</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
<citerefentry project='man-pages'><refentrytitle>fifo</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
<citerefentry project='man-pages'><refentrytitle>mq_overview</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
<citerefentry project='man-pages'><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
</para>
</refsect1>
</refentry>