man/sd_is_fifo.xml

   1 <?xml version='1.0'?> <!--*-nxml-*-->
   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
   3   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
   4
   5 <!--
   6   SPDX-License-Identifier: LGPL-2.1+
   7 -->
   8
   9 <refentry id="sd_is_fifo"
  10   xmlns:xi="http://www.w3.org/2001/XInclude">
  11
  12   <refentryinfo>
  13     <title>sd_is_fifo</title>
  14     <productname>systemd</productname>
  15   </refentryinfo>
  16
  17   <refmeta>
  18     <refentrytitle>sd_is_fifo</refentrytitle>
  19     <manvolnum>3</manvolnum>
  20   </refmeta>
  21
  22   <refnamediv>
  23     <refname>sd_is_fifo</refname>
  24     <refname>sd_is_socket</refname>
  25     <refname>sd_is_socket_inet</refname>
  26     <refname>sd_is_socket_unix</refname>
  27     <refname>sd_is_socket_sockaddr</refname>
  28     <refname>sd_is_mq</refname>
  29     <refname>sd_is_special</refname>
  30     <refpurpose>Check the type of a file descriptor</refpurpose>
  31   </refnamediv>
  32
  33   <refsynopsisdiv>
  34     <funcsynopsis>
  35       <funcsynopsisinfo>#include &lt;systemd/sd-daemon.h&gt;</funcsynopsisinfo>
  36
  37       <funcprototype>
  38         <funcdef>int <function>sd_is_fifo</function></funcdef>
  39         <paramdef>int <parameter>fd</parameter></paramdef>
  40         <paramdef>const char *<parameter>path</parameter></paramdef>
  41       </funcprototype>
  42
  43       <funcprototype>
  44         <funcdef>int <function>sd_is_socket</function></funcdef>
  45         <paramdef>int <parameter>fd</parameter></paramdef>
  46         <paramdef>int <parameter>family</parameter></paramdef>
  47         <paramdef>int <parameter>type</parameter></paramdef>
  48         <paramdef>int <parameter>listening</parameter></paramdef>
  49       </funcprototype>
  50
  51       <funcprototype>
  52         <funcdef>int <function>sd_is_socket_inet</function></funcdef>
  53         <paramdef>int <parameter>fd</parameter></paramdef>
  54         <paramdef>int <parameter>family</parameter></paramdef>
  55         <paramdef>int <parameter>type</parameter></paramdef>
  56         <paramdef>int <parameter>listening</parameter></paramdef>
  57         <paramdef>uint16_t <parameter>port</parameter></paramdef>
  58       </funcprototype>
  59
  60       <funcprototype>
  61         <funcdef>int <function>sd_is_socket_sockaddr</function></funcdef>
  62         <paramdef>int <parameter>fd</parameter></paramdef>
  63         <paramdef>int <parameter>type</parameter></paramdef>
  64         <paramdef>const struct sockaddr *<parameter>addr</parameter></paramdef>
  65         <paramdef>unsigned <parameter>addr_len</parameter></paramdef>
  66         <paramdef>int <parameter>listening</parameter></paramdef>
  67       </funcprototype>
  68
  69       <funcprototype>
  70         <funcdef>int <function>sd_is_socket_unix</function></funcdef>
  71         <paramdef>int <parameter>fd</parameter></paramdef>
  72         <paramdef>int <parameter>type</parameter></paramdef>
  73         <paramdef>int <parameter>listening</parameter></paramdef>
  74         <paramdef>const char *<parameter>path</parameter></paramdef>
  75         <paramdef>size_t <parameter>length</parameter></paramdef>
  76       </funcprototype>
  77
  78       <funcprototype>
  79         <funcdef>int <function>sd_is_mq</function></funcdef>
  80         <paramdef>int <parameter>fd</parameter></paramdef>
  81         <paramdef>const char *<parameter>path</parameter></paramdef>
  82       </funcprototype>
  83
  84       <funcprototype>
  85         <funcdef>int <function>sd_is_special</function></funcdef>
  86         <paramdef>int <parameter>fd</parameter></paramdef>
  87         <paramdef>const char *<parameter>path</parameter></paramdef>
  88       </funcprototype>
  89
  90     </funcsynopsis>
  91   </refsynopsisdiv>
  92
  93   <refsect1>
  94     <title>Description</title>
  95
  96     <para><function>sd_is_fifo()</function> may be called to check
  97     whether the specified file descriptor refers to a FIFO or pipe. If
  98     the <parameter>path</parameter> parameter is not
  99     <constant>NULL</constant>, it is checked whether the FIFO is bound
 100     to the specified file system path.</para>
 101
 102     <para><function>sd_is_socket()</function> may be called to check
 103     whether the specified file descriptor refers to a socket. If the
 104     <parameter>family</parameter> parameter is not
 105     <constant>AF_UNSPEC</constant>, it is checked whether the socket
 106     is of the specified family (<constant>AF_UNIX</constant>,
 107     <constant>AF_INET</constant>, …). If the <parameter>type</parameter>
 108     parameter is not 0, it is checked whether the socket is of the
 109     specified type (<constant>SOCK_STREAM</constant>,
 110     <constant>SOCK_DGRAM</constant>, …). If the
 111     <parameter>listening</parameter> parameter is positive, it is
 112     checked whether the socket is in accepting mode, i.e.
 113     <function>listen()</function> has been called for it. If
 114     <parameter>listening</parameter> is 0, it is checked whether the
 115     socket is not in this mode. If the parameter is negative, no such
 116     check is made. The <parameter>listening</parameter> parameter
 117     should only be used for stream sockets and should be set to a
 118     negative value otherwise.</para>
 119
 120     <para><function>sd_is_socket_inet()</function> is similar to
 121     <function>sd_is_socket()</function>, but optionally checks the
 122     IPv4 or IPv6 port number the socket is bound to, unless
 123     <parameter>port</parameter> is zero. For this call
 124     <parameter>family</parameter> must be passed as either
 125     <constant>AF_UNSPEC</constant>, <constant>AF_INET</constant>, or
 126     <constant>AF_INET6</constant>.</para>
 127
 128     <para><function>sd_is_socket_sockaddr()</function> is similar to
 129     <function>sd_is_socket_inet()</function>, but checks if the socket is bound to the
 130     address specified by <parameter>addr</parameter>. The
 131     <structfield>family</structfield> specified by <parameter>addr</parameter> must be
 132     either <constant>AF_INET</constant> or <constant>AF_INET6</constant> and
 133     <parameter>addr_len</parameter> must be large enough for that family. If
 134     <parameter>addr</parameter> specifies a non-zero port, it is also checked if the
 135     socket is bound to this port. In addition, for IPv6, if <parameter>addr</parameter>
 136     specifies non-zero <structfield>sin6_flowinfo</structfield> or
 137     <structfield>sin6_scope_id</structfield>, it is checked if the socket has the same
 138     values.</para>
 139
 140     <para><function>sd_is_socket_unix()</function> is similar to
 141     <function>sd_is_socket()</function> but optionally checks the
 142     <constant>AF_UNIX</constant> path the socket is bound to, unless
 143     the <parameter>path</parameter> parameter is
 144     <constant>NULL</constant>. For normal file system
 145     <constant>AF_UNIX</constant> sockets, set the
 146     <parameter>length</parameter> parameter to 0. For Linux abstract
 147     namespace sockets, set the <parameter>length</parameter> to the
 148     size of the address, including the initial 0 byte, and set the
 149     <parameter>path</parameter> to the initial 0 byte of the socket
 150     address.</para>
 151
 152     <para><function>sd_is_mq()</function> may be called to check
 153     whether the specified file descriptor refers to a POSIX message
 154     queue. If the <parameter>path</parameter> parameter is not
 155     <constant>NULL</constant>, it is checked whether the message queue
 156     is bound to the specified name.</para>
 157
 158     <para><function>sd_is_special()</function> may be called to check
 159     whether the specified file descriptor refers to a special file. If
 160     the <parameter>path</parameter> parameter is not
 161     <constant>NULL</constant>, it is checked whether the file
 162     descriptor is bound to the specified filename. Special files in
 163     this context are character device nodes and files in
 164     <filename>/proc</filename> or <filename>/sys</filename>.</para>
 165   </refsect1>
 166
 167   <refsect1>
 168     <title>Return Value</title>
 169
 170     <para>On failure, these calls return a negative errno-style error
 171     code. If the file descriptor is of the specified type and bound to
 172     the specified address, a positive return value is returned,
 173     otherwise zero.</para>
 174   </refsect1>
 175
 176   <refsect1>
 177     <title>Notes</title>
 178
 179     <xi:include href="libsystemd-pkgconfig.xml" xpointer="pkgconfig-text"/>
 180
 181     <para>Internally, these function use a combination of
 182     <filename>fstat()</filename> and
 183     <filename>getsockname()</filename> to check the file descriptor
 184     type and where it is bound to.</para>
 185   </refsect1>
 186
 187   <refsect1>
 188     <title>See Also</title>
 189     <para>
 190       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 191       <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 192       <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 193       <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 194       <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 195       <citerefentry project='man-pages'><refentrytitle>ip</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 196       <citerefentry project='man-pages'><refentrytitle>ipv6</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 197       <citerefentry project='man-pages'><refentrytitle>unix</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 198       <citerefentry project='man-pages'><refentrytitle>fifo</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 199       <citerefentry project='man-pages'><refentrytitle>mq_overview</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 200       <citerefentry project='man-pages'><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
 201     </para>
 202   </refsect1>
 203
 204 </refentry>