man/sd_is_fifo.xml

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  23
  24 <refentry id="sd_is_fifo"
  25         xmlns:xi="http://www.w3.org/2001/XInclude">
  26
  27         <refentryinfo>
  28                 <title>sd_is_fifo</title>
  29                 <productname>systemd</productname>
  30
  31                 <authorgroup>
  32                         <author>
  33                                 <contrib>Developer</contrib>
  34                                 <firstname>Lennart</firstname>
  35                                 <surname>Poettering</surname>
  36                                 <email>lennart@poettering.net</email>
  37                         </author>
  38                 </authorgroup>
  39         </refentryinfo>
  40
  41         <refmeta>
  42                 <refentrytitle>sd_is_fifo</refentrytitle>
  43                 <manvolnum>3</manvolnum>
  44         </refmeta>
  45
  46         <refnamediv>
  47                 <refname>sd_is_fifo</refname>
  48                 <refname>sd_is_socket</refname>
  49                 <refname>sd_is_socket_inet</refname>
  50                 <refname>sd_is_socket_unix</refname>
  51                 <refname>sd_is_mq</refname>
  52                 <refname>sd_is_special</refname>
  53                 <refpurpose>Check the type of a file descriptor</refpurpose>
  54         </refnamediv>
  55
  56         <refsynopsisdiv>
  57                 <funcsynopsis>
  58                         <funcsynopsisinfo>#include &lt;systemd/sd-daemon.h&gt;</funcsynopsisinfo>
  59
  60                         <funcprototype>
  61                                 <funcdef>int <function>sd_is_fifo</function></funcdef>
  62                                 <paramdef>int <parameter>fd</parameter></paramdef>
  63                                 <paramdef>const char *<parameter>path</parameter></paramdef>
  64                         </funcprototype>
  65
  66                         <funcprototype>
  67                                 <funcdef>int <function>sd_is_socket</function></funcdef>
  68                                 <paramdef>int <parameter>fd</parameter></paramdef>
  69                                 <paramdef>int <parameter>family</parameter></paramdef>
  70                                 <paramdef>int <parameter>type</parameter></paramdef>
  71                                 <paramdef>int <parameter>listening</parameter></paramdef>
  72                         </funcprototype>
  73
  74                         <funcprototype>
  75                                 <funcdef>int <function>sd_is_socket_inet</function></funcdef>
  76                                 <paramdef>int <parameter>fd</parameter></paramdef>
  77                                 <paramdef>int <parameter>family</parameter></paramdef>
  78                                 <paramdef>int <parameter>type</parameter></paramdef>
  79                                 <paramdef>int <parameter>listening</parameter></paramdef>
  80                                 <paramdef>uint16_t <parameter>port</parameter></paramdef>
  81                         </funcprototype>
  82
  83                         <funcprototype>
  84                                 <funcdef>int <function>sd_is_socket_unix</function></funcdef>
  85                                 <paramdef>int <parameter>fd</parameter></paramdef>
  86                                 <paramdef>int <parameter>type</parameter></paramdef>
  87                                 <paramdef>int <parameter>listening</parameter></paramdef>
  88                                 <paramdef>const char* <parameter>path</parameter></paramdef>
  89                                 <paramdef>size_t <parameter>length</parameter></paramdef>
  90                         </funcprototype>
  91
  92                         <funcprototype>
  93                                 <funcdef>int <function>sd_is_mq</function></funcdef>
  94                                 <paramdef>int <parameter>fd</parameter></paramdef>
  95                                 <paramdef>const char *<parameter>path</parameter></paramdef>
  96                         </funcprototype>
  97
  98                         <funcprototype>
  99                                 <funcdef>int <function>sd_is_special</function></funcdef>
 100                                 <paramdef>int <parameter>fd</parameter></paramdef>
 101                                 <paramdef>const char *<parameter>path</parameter></paramdef>
 102                         </funcprototype>
 103
 104                 </funcsynopsis>
 105         </refsynopsisdiv>
 106
 107         <refsect1>
 108                 <title>Description</title>
 109
 110                 <para><function>sd_is_fifo()</function> may be called
 111                 to check whether the specified file descriptor refers
 112                 to a FIFO or pipe. If the <parameter>path</parameter>
 113                 parameter is not <constant>NULL</constant>, it is
 114                 checked whether the FIFO is bound to the specified
 115                 file system path.</para>
 116
 117                 <para><function>sd_is_socket()</function> may be
 118                 called to check whether the specified file descriptor
 119                 refers to a socket. If the
 120                 <parameter>family</parameter> parameter is not
 121                 <constant>AF_UNSPEC</constant>, it is checked whether
 122                 the socket is of the specified family (AF_UNIX,
 123                 <constant>AF_INET</constant>, ...). If the
 124                 <parameter>type</parameter> parameter is not 0, it is
 125                 checked whether the socket is of the specified type
 126                 (<constant>SOCK_STREAM</constant>,
 127                 <constant>SOCK_DGRAM</constant>, ...). If the
 128                 <parameter>listening</parameter> parameter is positive,
 129                 it is checked whether the socket is in accepting mode,
 130                 i.e. <function>listen()</function> has been called for
 131                 it. If <parameter>listening</parameter> is 0, it is
 132                 checked whether the socket is not in this mode. If the
 133                 parameter is negative, no such check is made. The
 134                 <parameter>listening</parameter> parameter should only
 135                 be used for stream sockets and should be set to a
 136                 negative value otherwise.</para>
 137
 138                 <para><function>sd_is_socket_inet()</function> is
 139                 similar to <function>sd_is_socket()</function>, but
 140                 optionally checks the IPv4 or IPv6 port number the
 141                 socket is bound to, unless <parameter>port</parameter>
 142                 is zero. For this call <parameter>family</parameter>
 143                 must be passed as either <constant>AF_UNSPEC</constant>, <constant>AF_INET</constant>, or
 144                 <constant>AF_INET6</constant>.</para>
 145
 146                 <para><function>sd_is_socket_unix()</function> is
 147                 similar to <function>sd_is_socket()</function> but
 148                 optionally checks the <constant>AF_UNIX</constant> path the socket is bound
 149                 to, unless the <parameter>path</parameter> parameter
 150                 is <constant>NULL</constant>. For normal file system <constant>AF_UNIX</constant> sockets,
 151                 set the <parameter>length</parameter> parameter to 0. For
 152                 Linux abstract namespace sockets, set the
 153                 <parameter>length</parameter> to the size of the
 154                 address, including the initial 0 byte, and set the
 155                 <parameter>path</parameter> to the initial 0 byte of
 156                 the socket address.</para>
 157
 158                 <para><function>sd_is_mq()</function> may be called to
 159                 check whether the specified file descriptor refers to
 160                 a POSIX message queue. If the
 161                 <parameter>path</parameter> parameter is not
 162                 <constant>NULL</constant>, it is checked whether the
 163                 message queue is bound to the specified name.</para>
 164
 165                 <para><function>sd_is_special()</function> may be
 166                 called to check whether the specified file descriptor
 167                 refers to a special file. If the
 168                 <parameter>path</parameter> parameter is not
 169                 <constant>NULL</constant>, it is checked whether the file
 170                 descriptor is bound to the specified file
 171                 name. Special files in this context are character
 172                 device nodes and files in <filename>/proc</filename>
 173                 or <filename>/sys</filename>.</para>
 174         </refsect1>
 175
 176         <refsect1>
 177                 <title>Return Value</title>
 178
 179                 <para>On failure, these calls return a negative
 180                 errno-style error code. If the file descriptor is of
 181                 the specified type and bound to the specified address,
 182                 a positive return value is returned, otherwise
 183                 zero.</para>
 184         </refsect1>
 185
 186         <refsect1>
 187                 <title>Notes</title>
 188
 189                 <xi:include href="libsystemd-pkgconfig.xml" xpointer="pkgconfig-text"/>
 190
 191                 <para>Internally, these function use a combination of
 192                 <filename>fstat()</filename> and
 193                 <filename>getsockname()</filename> to check the file
 194                 descriptor type and where it is bound to.</para>
 195         </refsect1>
 196
 197         <refsect1>
 198                 <title>See Also</title>
 199                 <para>
 200                         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 201                         <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 202                         <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 203                         <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 204                         <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 205                 </para>
 206         </refsect1>
 207
 208 </refentry>