along with systemd; If not, see <http://www.gnu.org/licenses/>.
-->
-<refentry id="sd_listen_fds">
+<refentry id="sd_listen_fds"
+ xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>sd_listen_fds</title>
<refnamediv>
<refname>sd_listen_fds</refname>
<refname>SD_LISTEN_FDS_START</refname>
- <refpurpose>Check for file descriptors passed by the init system.</refpurpose>
+ <refpurpose>Check for file descriptors passed by the system manager</refpurpose>
</refnamediv>
<refsynopsisdiv>
activation logic.</para>
<para>If the <parameter>unset_environment</parameter>
- parameter is non-zero
+ parameter is non-zero,
<function>sd_listen_fds()</function> will unset the
<varname>$LISTEN_FDS</varname>/<varname>$LISTEN_PID</varname>
- environment variables before returning (regardless
+ environment variables before returning (regardless of
whether the function call itself succeeded or
not). Further calls to
<function>sd_listen_fds()</function> will then fail,
<para>If a daemon receives more than one file
descriptor, they will be passed in the same order as
configured in the systemd socket definition
- file. Nonetheless it is recommended to verify the
+ file. Nonetheless, it is recommended to verify the
correct socket types before using them. To simplify
- this checking the functions
+ this checking, the functions
<citerefentry><refentrytitle>sd_is_fifo</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_is_socket</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_is_socket_inet</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_is_socket_unix</refentrytitle><manvolnum>3</manvolnum></citerefentry>
- are provided. In order to maximize flexibility it is
+ are provided. In order to maximize flexibility, it is
recommended to make these checks as loose as possible
- without allowing incorrect setups. i.e. often the
+ without allowing incorrect setups. i.e. often, the
actual port number a socket is bound to matters little
for the service to work, hence it should not be
verified. On the other hand, whether a socket is a
<varname>$LISTEN_FDS</varname>/<varname>$LISTEN_PID</varname>
was not set or was not correctly set for this daemon and
hence no file descriptors were received, 0 is
- returned. Otherwise the number of file descriptors
+ returned. Otherwise, the number of file descriptors
passed is returned. The application may find them
starting with file descriptor SD_LISTEN_FDS_START,
i.e. file descriptor 3.</para>
<refsect1>
<title>Notes</title>
- <para>This function is provided by the reference
- implementation of APIs for new-style daemons and
- distributed with the systemd package. The algorithm it
- implements is simple, and can easily be reimplemented
- in daemons if it is important to support this
- interface without using the reference
- implementation.</para>
+ <xi:include href="libsystemd-pkgconfig.xml" xpointer="pkgconfig-text"/>
<para>Internally, this function checks whether the
<varname>$LISTEN_PID</varname> environment variable
equals the daemon PID. If not, it returns
- immediately. Otherwise it parses the number passed in
+ immediately. Otherwise, it parses the number passed in
the <varname>$LISTEN_FDS</varname> environment
variable, then sets the FD_CLOEXEC flag for the parsed
number of file descriptors starting from
- SD_LISTEN_FDS_START. Finally it returns the parsed
+ SD_LISTEN_FDS_START. Finally, it returns the parsed
number.</para>
-
- <para>For details about the algorithm check the
- liberally licensed reference implementation sources:
- <ulink url="http://cgit.freedesktop.org/systemd/systemd/plain/src/sd-daemon.c"/>
- resp. <ulink
- url="http://cgit.freedesktop.org/systemd/systemd/plain/src/systemd/sd-daemon.h"/></para>
-
- <para><function>sd_listen_fds()</function> is
- 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>If the reference implementation is used as
- drop-in files and -DDISABLE_SYSTEMD is set during
- compilation this function will always return 0 and
- otherwise become a NOP.</para>
</refsect1>
<refsect1>
<title>Environment</title>
- <variablelist>
+ <variablelist class='environment-variables'>
<varlistentry>
<term><varname>$LISTEN_PID</varname></term>
<term><varname>$LISTEN_FDS</varname></term>
~ianmdlvl / elogind.git / blobdiff