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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.
214 lines
8.3 KiB
XML
214 lines
8.3 KiB
XML
<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
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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 2015 Zbigniew Jędrzejewski-Szmek
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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_event_wait">
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<refentryinfo>
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<title>sd_event_wait</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>Tom</firstname>
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<surname>Gundersen</surname>
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<email>teg@jklm.no</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_event_wait</refentrytitle>
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<manvolnum>3</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>sd_event_wait</refname>
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<refname>sd_event_prepare</refname>
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<refname>sd_event_dispatch</refname>
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<refpurpose>Run parts of libsystemd event loop</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<funcsynopsis>
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<funcsynopsisinfo>#include <systemd/sd-event.h></funcsynopsisinfo>
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<funcprototype>
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<funcdef>int <function>sd_event_prepare</function></funcdef>
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<paramdef>sd_event *<parameter>event</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_event_wait</function></funcdef>
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<paramdef>sd_event *<parameter>event</parameter></paramdef>
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<paramdef>uint64_t <parameter>timeout</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_event_dispatch</function></funcdef>
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<paramdef>sd_event *<parameter>event</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>Functions described here form parts of an event loop.</para>
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<para><function>sd_event_prepare</function> checks for pending
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events and arms necessary timers. If any events are ready to be
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processed, it returns a positive value, and the events should be
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processed with <function>sd_event_dispatch</function>.
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<function>sd_event_dispatch</function> runs a handler for one of
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the events from the sources with the highest priority. On success,
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<function>sd_event_dispatch</function> returns either 0, which
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means that the loop is finished, or a positive value, which means
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that the loop is again in the initial state and
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<function>sd_event_prepare</function> should be called again.
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</para>
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<para>In case <function>sd_event_prepare</function> returned 0,
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<function>sd_event_wait</function> should be called to wait for
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events or a timeout. If any events are ready to be processed, it
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returns a positive value, and the events should be processed with
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<function>sd_event_dispatch</function>. Otherwise, the loop is
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back in the initial state and <function>sd_event_prepare</function>
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should be called again.</para>
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<programlisting>
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┌──────────┐
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│ initial ├──←←←←←←←←←←←←←←←←←←←─┐
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└───┬──────┘ ↑
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│ ↑
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sd_event_prepare ┌─────────┐ ↑
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├ 0 →→→→→→→──┤ armed │ ↑
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1 └───┬─────┘ ↑
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↓ │ ↑
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↓ sd_event_wait ↑
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├───←←←←←←←─── 1 ┴─ 0 →→→→→→→─┘
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┌───┴──────┐ ↑
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│ pending │ ↑
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└───┬──────┘ ↑
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│ ↑
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sd_event_dispatch ↑
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↓ ↑
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├ 1 ──────────→→→→→→→─────────┘
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0
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↓
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┌───┴──────┐
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│ finished │
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└──────────┘
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</programlisting>
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<para>All three functions as the first argument take the event
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loop object <parameter>event</parameter> that is created with with
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<function>sd_event_new</function>. The timeout for
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<function>sd_event_wait</function> is specified with
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<parameter>timeout</parameter> in milliseconds.
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<constant>(uint64_t) -1</constant> may be used to specify an
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infinite timeout.</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 success, these functions return 0 or a positive integer.
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On failure, they return a negative errno-style error code. In case
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of <function>sd_event_prepare</function> and
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<function>sd_event_wait</function> a positive value means that
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events are ready to be processed and 0 means that no events are
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ready. In case of <function>sd_event_dispatch</function> a
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positive value means that the loop is again in the initial state
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and 0 means the loop is finished. For any of those functions, a
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negative return value means the loop must be aborted.</para>
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</refsect1>
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<refsect1>
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<title>Errors</title>
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<para>Returned errors may indicate the following problems:</para>
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<variablelist>
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<varlistentry>
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<term><constant>-EINVAL</constant></term>
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<listitem><para>Parameter <parameter>event</parameter> is
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<constant>NULL</constant>.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-EBUSY</constant></term>
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<listitem><para>The event loop object is not in the right
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state.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-ESTALE</constant></term>
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<listitem><para>The event loop is already terminated.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-ECHILD</constant></term>
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<listitem><para>The event loop has been created in a different process.</para></listitem>
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</varlistentry>
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</variablelist>
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<para>Other errors are possible too.</para>
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</refsect1>
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<refsect1>
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<title>Notes</title>
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<para>Functions described here are available
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as a shared library, which can be compiled and linked to with the
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<constant>libsystemd</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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file.</para>
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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_event_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_event_run</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_event_add_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_event_add_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_event_add_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_event_add_post</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
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</para>
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</refsect1>
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</refentry>
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