[thirdparty/systemd.git] / man / sd_is_fifo.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">

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  This file is part of systemd.

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  systemd is free software; you can redistribute it and/or modify it
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  (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
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  You should have received a copy of the GNU General Public License
  along with systemd; If not, see <http://www.gnu.org/licenses/>.
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<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. It 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/plain/src/sd-daemon.c"/>
                resp. <ulink
                url="http://cgit.freedesktop.org/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>7</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>7</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>
Commit	Line	Data
f9378423 LP	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	This file is part of systemd.
	7
	8	Copyright 2010 Lennart Poettering
	9
	10	systemd is free software; you can redistribute it and/or modify it
	11	under the terms of the GNU General Public License as published by
	12	the Free Software Foundation; either version 2 of the License, or
	13	(at your option) any later version.
	14
	15	systemd is distributed in the hope that it will be useful, but
	16	WITHOUT ANY WARRANTY; without even the implied warranty of
	17	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	18	General Public License for more details.
	19
	20	You should have received a copy of the GNU General Public License
	21	along with systemd; If not, see <http://www.gnu.org/licenses/>.
	22	-->
	23
	24	<refentry id="sd_is_fifo">
	25
	26	<refentryinfo>
	27	<title>sd_is_fifo</title>
	28	<productname>systemd</productname>
	29
	30	<authorgroup>
	31	<author>
	32	<contrib>Developer</contrib>
	33	<firstname>Lennart</firstname>
	34	<surname>Poettering</surname>
	35	<email>lennart@poettering.net</email>
	36	</author>
	37	</authorgroup>
	38	</refentryinfo>
	39
	40	<refmeta>
	41	<refentrytitle>sd_is_fifo</refentrytitle>
	42	<manvolnum>3</manvolnum>
	43	</refmeta>
	44
	45	<refnamediv>
	46	<refname>sd_is_fifo</refname>
	47	<refname>sd_is_socket</refname>
	48	<refname>sd_is_socket_inet</refname>
	49	<refname>sd_is_socket_unix</refname>
916abb21	50	<refname>sd_is_mq</refname>
f9378423 LP	51	<refpurpose>Check the type of a file descriptor</refpurpose>
	52	</refnamediv>
	53
	54	<refsynopsisdiv>
	55	<funcsynopsis>
a822cbfa	56	<funcsynopsisinfo>#include <systemd/sd-daemon.h></funcsynopsisinfo>
f9378423 LP	57
	58	<funcprototype>
	59	<funcdef>int <function>sd_is_fifo</function></funcdef>
	60	<paramdef>int <parameter>fd</parameter></paramdef>
	61	<paramdef>const char *<parameter>path</parameter></paramdef>
	62	</funcprototype>
	63
	64	<funcprototype>
	65	<funcdef>int <function>sd_is_socket</function></funcdef>
	66	<paramdef>int <parameter>fd</parameter></paramdef>
	67	<paramdef>int <parameter>family</parameter></paramdef>
	68	<paramdef>int <parameter>type</parameter></paramdef>
	69	<paramdef>int <parameter>listening</parameter></paramdef>
	70	</funcprototype>
	71
	72	<funcprototype>
	73	<funcdef>int <function>sd_is_socket_inet</function></funcdef>
	74	<paramdef>int <parameter>fd</parameter></paramdef>
	75	<paramdef>int <parameter>family</parameter></paramdef>
	76	<paramdef>int <parameter>type</parameter></paramdef>
	77	<paramdef>int <parameter>listening</parameter></paramdef>
	78	<paramdef>uint16_t <parameter>port</parameter></paramdef>
	79	</funcprototype>
	80
	81	<funcprototype>
	82	<funcdef>int <function>sd_is_socket_unix</function></funcdef>
	83	<paramdef>int <parameter>fd</parameter></paramdef>
	84	<paramdef>int <parameter>type</parameter></paramdef>
	85	<paramdef>int <parameter>listening</parameter></paramdef>
	86	<paramdef>const char* <parameter>path</parameter></paramdef>
	87	<paramdef>size_t <parameter>length</parameter></paramdef>
	88	</funcprototype>
	89
916abb21 LP	90	<funcprototype>
	91	<funcdef>int <function>sd_is_mq</function></funcdef>
	92	<paramdef>int <parameter>fd</parameter></paramdef>
	93	<paramdef>const char *<parameter>path</parameter></paramdef>
	94	</funcprototype>
	95
f9378423 LP	96	</funcsynopsis>
	97	</refsynopsisdiv>
	98
	99	<refsect1>
	100	<title>Description</title>
	101
	102	<para><function>sd_is_fifo()</function> may be called
	103	to check whether the specified file descriptor refers
af62c704 KS	104	to a FIFO or pipe. If the <parameter>path</parameter>
af62c704 KS	105	parameter is not NULL, it is checked whether the FIFO
f9378423 LP	106	is bound to the specified file system path.</para>
	107
	108	<para><function>sd_is_socket()</function> may be
	109	called to check whether the specified file descriptor
	110	refers to a socket. It the
	111	<parameter>family</parameter> parameter is not
	112	AF_UNSPEC it is checked whether the socket is of the
	113	specified family (AF_UNIX, AF_INET, ...). If the
	114	<parameter>type</parameter> parameter is not 0 it is
	115	checked whether the socket is of the specified type
	116	(SOCK_STREAM, SOCK_DGRAM, ...). If the
	117	<parameter>listening</parameter> parameter is positive
	118	it is checked whether the socket is in accepting mode,
	119	i.e. <function>listen()</function> has been called for
	120	it. If <parameter>listening</parameter> is 0, it is
	121	checked whether the socket is not in this mode. If the
	122	parameter is negative, no such check is made. The
	123	<parameter>listening</parameter> parameter should only
	124	be used for stream sockets and should be set to a
	125	negative value otherwise.</para>
	126
	127	<para><function>sd_is_socket_inet()</function> is
	128	similar to <function>sd_is_socket()</function>, but
	129	optionally checks the IPv4 or IPv6 port number the
	130	socket is bound to, unless <parameter>port</parameter>
	131	is zero. For this call <parameter>family</parameter>
	132	must be passed as either AF_UNSPEC, AF_INET or
	133	AF_INET6.</para>
	134
	135	<para><function>sd_is_socket_unix()</function> is
	136	similar to <function>sd_is_socket()</function>, but
	137	optionally checks the AF_UNIX path the socket is bound
	138	to, unless the <parameter>path</parameter> parameter
	139	is NULL. For normal file system AF_UNIX sockets set
	140	the <parameter>length</parameter> parameter to 0. For
	141	Linux abstract namespace sockets set the
	142	<parameter>length</parameter> to the size of the
	143	address, including the initial 0 byte and set
	144	<parameter>path</parameter> to the initial 0 byte of
	145	the socket address.</para>
916abb21 LP	146
	147	<para><function>sd_is_mq()</function> may be called to
	148	check whether the specified file descriptor refers to
	149	a POSIX message queue. If the
	150	<parameter>path</parameter> parameter is not NULL, it
	151	is checked whether the message queue is bound to the
	152	specified name.</para>
f9378423 LP	153	</refsect1>
	154
	155	<refsect1>
	156	<title>Return Value</title>
	157
	158	<para>On failure, these calls return a negative
	159	errno-style error code. If the file descriptor is of
	160	the specified type and bound to the specified address
	161	a positive return value is returned, otherwise
	162	zero.</para>
	163	</refsect1>
	164
	165	<refsect1>
	166	<title>Notes</title>
	167
	168	<para>These functions are provided by the reference
	169	implementation of APIs for new-style daemons and
	170	distributed with the systemd package. The algorithms
	171	they implement are simple, and can easily be
	172	reimplemented in daemons if it is important to support
	173	this interface without using the reference
	174	implementation.</para>
	175
	176	<para>Internally, these function use a combination of
	177	<filename>fstat()</filename> and
	178	<filename>getsockname()</filename> to check the file
	179	descriptor type and where it is bound to.</para>
	180
71e6c1cf	181	<para>For details about the algorithms check the
f9378423	182	liberally licensed reference implementation sources:
8ab49c12	183	<ulink url="http://cgit.freedesktop.org/systemd/plain/src/sd-daemon.c"/>
f9378423	184	resp. <ulink
8ab49c12	185	url="http://cgit.freedesktop.org/systemd/plain/src/systemd/sd-daemon.h"/></para>
f9378423 LP	186
	187	<para><function>sd_is_fifo()</function> and the
	188	related functions are implemented in the reference
71e6c1cf LP	189	implementation's <filename>sd-daemon.c</filename> and
	190	<filename>sd-daemon.h</filename> files. These
	191	interfaces are available as shared library, which can
	192	be compiled and linked to with the
	193	<literal>libsystemd-daemon</literal>
	194	<citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
	195	file. Alternatively, applications consuming these APIs
	196	may copy the implementation into their source
	197	tree. For more details about the reference
	198	implementation see
	199	<citerefentry><refentrytitle>sd_daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
f9378423 LP	200
	201	<para>These functions continue to work as described,
	202	even if -DDISABLE_SYSTEMD is set during
	203	compilation.</para>
	204	</refsect1>
	205
	206	<refsect1>
	207	<title>See Also</title>
	208	<para>
160cd5c9 LP	209	<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
160cd5c9 LP	210	<citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
f9378423	211	<citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
f9378423 LP	212	<citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
f9378423 LP	213	<citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>
af62c704	214	</para>
f9378423 LP	215	</refsect1>
	216
	217	</refentry>