12b42c7667
This did not really work out as we had hoped. Trying to do this upstream introduced several problems that probably makes it better suited as a downstream patch after all. At any rate, it is not releaseable in the current state, so we at least need to revert this before the release. * by adjusting the path to binaries, but not do the same thing to the search path we end up with inconsistent man-pages. Adjusting the search path too would be quite messy, and it is not at all obvious that this is worth the effort, but at any rate it would have to be done before we could ship this. * this means that distributed man-pages does not make sense as they depend on config options, and for better or worse we are still distributing man pages, so that is something that definitely needs sorting out before we could ship with this patch. * we have long held that split-usr is only minimally supported in order to boot, and something we hope will eventually go away. So before we start adding even more magic/effort in order to make this work nicely, we should probably question if it makes sense at all.
177 lines
7.2 KiB
XML
177 lines
7.2 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!--
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This file is part of systemd.
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Copyright 2010 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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-->
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<refentry id="sd_listen_fds"
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xmlns:xi="http://www.w3.org/2001/XInclude">
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<refentryinfo>
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<title>sd_listen_fds</title>
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<productname>systemd</productname>
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<authorgroup>
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<author>
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<contrib>Developer</contrib>
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<firstname>Lennart</firstname>
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<surname>Poettering</surname>
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<email>lennart@poettering.net</email>
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</author>
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</authorgroup>
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</refentryinfo>
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<refmeta>
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<refentrytitle>sd_listen_fds</refentrytitle>
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<manvolnum>3</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>sd_listen_fds</refname>
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<refname>SD_LISTEN_FDS_START</refname>
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<refpurpose>Check for file descriptors passed by the system manager</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<funcsynopsis>
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<funcsynopsisinfo>#include <systemd/sd-daemon.h></funcsynopsisinfo>
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<funcsynopsisinfo>#define SD_LISTEN_FDS_START 3</funcsynopsisinfo>
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<funcprototype>
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<funcdef>int <function>sd_listen_fds</function></funcdef>
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<paramdef>int <parameter>unset_environment</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para><function>sd_listen_fds()</function> shall be called by a
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daemon to check for file descriptors passed by the init system as
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part of the socket-based activation logic.</para>
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<para>If the <parameter>unset_environment</parameter> parameter is
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non-zero, <function>sd_listen_fds()</function> will unset the
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<varname>$LISTEN_FDS</varname> and <varname>$LISTEN_PID</varname>
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environment variables before returning (regardless of whether the
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function call itself succeeded or not). Further calls to
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<function>sd_listen_fds()</function> will then fail, but the
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variables are no longer inherited by child processes.</para>
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<para>If a daemon receives more than one file descriptor, they
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will be passed in the same order as configured in the systemd
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socket unit file (see
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<citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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for details). Nonetheless, it is recommended to verify the correct
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socket types before using them. To simplify this checking, the
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functions
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<citerefentry><refentrytitle>sd_is_fifo</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_is_socket</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_is_socket_inet</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_is_socket_unix</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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are provided. In order to maximize flexibility, it is recommended
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to make these checks as loose as possible without allowing
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incorrect setups. i.e. often, the actual port number a socket is
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bound to matters little for the service to work, hence it should
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not be verified. On the other hand, whether a socket is a datagram
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or stream socket matters a lot for the most common program logics
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and should be checked.</para>
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<para>This function call will set the FD_CLOEXEC flag for all
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passed file descriptors to avoid further inheritance to children
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of the calling process.</para>
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<para>If multiple socket units activate the same service the order
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of the file descriptors passed to its main process is undefined.
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If additional file descriptors have been passed to the service
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manager using
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<citerefentry><refentrytitle>sd_pid_notify_with_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>'s
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<literal>FDSTORE=1</literal> messages, these file descriptors are
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passed last, in arbitrary order, and with duplicates
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removed.</para>
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</refsect1>
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<refsect1>
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<title>Return Value</title>
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<para>On failure, this call returns a negative errno-style error
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code. If
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<varname>$LISTEN_FDS</varname>/<varname>$LISTEN_PID</varname> was
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not set or was not correctly set for this daemon and hence no file
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descriptors were received, 0 is returned. Otherwise, the number of
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file descriptors passed is returned. The application may find them
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starting with file descriptor SD_LISTEN_FDS_START, i.e. file
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descriptor 3.</para>
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</refsect1>
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<refsect1>
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<title>Notes</title>
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<xi:include href="libsystemd-pkgconfig.xml" xpointer="pkgconfig-text"/>
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<para>Internally, this function checks whether the
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<varname>$LISTEN_PID</varname> environment variable equals the
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daemon PID. If not, it returns immediately. Otherwise, it parses
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the number passed in the <varname>$LISTEN_FDS</varname>
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environment variable, then sets the FD_CLOEXEC flag for the parsed
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number of file descriptors starting from SD_LISTEN_FDS_START.
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Finally, it returns the parsed number.</para>
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</refsect1>
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<refsect1>
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<title>Environment</title>
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<variablelist class='environment-variables'>
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<varlistentry>
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<term><varname>$LISTEN_PID</varname></term>
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<term><varname>$LISTEN_FDS</varname></term>
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<listitem><para>Set by the init system
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for supervised processes that use
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socket-based activation. This
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environment variable specifies the
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data
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<function>sd_listen_fds()</function>
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parses. See above for
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details.</para></listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<para>
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_is_fifo</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_is_socket</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_is_socket_inet</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_is_socket_unix</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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