travis: use UBSan checks from OSS-Fuzz

[thirdparty/systemd.git] / man / systemd-fstab-generator.xml

diff --git a/man/systemd-fstab-generator.xml b/man/systemd-fstab-generator.xml
index 5f37e9193e78540d1e46fa53a1ab376b912facdf..82321c44bf85a4a692ba6a6e2c1f1c18e51d52f9 100644 (file)
--- a/man/systemd-fstab-generator.xml
+++ b/man/systemd-fstab-generator.xml
@@ -1,38 +1,13 @@
 <?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">
-<!--
-  This file is part of systemd.
-
-  Copyright 2012 Lennart Poettering
-
-  systemd is free software; you can redistribute it and/or modify it
-  under the terms of the GNU Lesser General Public License as published by
-  the Free Software Foundation; either version 2.1 of the License, or
-  (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
-  Lesser General Public License for more details.
-
-  You should have received a copy of the GNU Lesser General Public License
-  along with systemd; If not, see <http://www.gnu.org/licenses/>.
--->
+<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
+  "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
+<!-- SPDX-License-Identifier: LGPL-2.1+ -->
 <refentry id="systemd-fstab-generator">
 
   <refentryinfo>
     <title>systemd-fstab-generator</title>
     <productname>systemd</productname>
-
-    <authorgroup>
-      <author>
-        <contrib>Developer</contrib>
-        <firstname>Lennart</firstname>
-        <surname>Poettering</surname>
-        <email>lennart@poettering.net</email>
-      </author>
-    </authorgroup>
   </refentryinfo>
 
   <refmeta>
@@ -71,6 +46,14 @@
     for more information about special <filename>/etc/fstab</filename>
     mount options this generator understands.</para>
 
+    <para>One special topic is handling of symbolic links.  Historical init
+    implementations supported symlinks in <filename>/etc/fstab</filename>.
+    Because mount units will refuse mounts where the target is a symbolic link,
+    this generator will resolve any symlinks as far as possible when processing
+    <filename>/etc/fstab</filename> in order to enhance backwards compatibility.
+    If a symlink target does not exist at the time that this generator runs, it
+    is assumed that the symlink target is the final target of the mount.</para>
+
     <para><filename>systemd-fstab-generator</filename> implements
     <citerefentry><refentrytitle>systemd.generator</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
   </refsect1>
@@ -191,19 +174,25 @@
         lost at shutdown, as <filename>/etc</filename> and <filename>/var</filename> will be served from the (initially
         unpopulated) volatile memory file system.</para>
 
-        <para>If set to <option>state</option> the generator will leave the root
-        directory mount point unaltered, however will mount a <literal>tmpfs</literal> file system to
-        <filename>/var</filename>. In this mode the normal system configuration (i.e the contents of
-        <literal>/etc</literal>) is in effect (and may be modified during system runtime), however the system state
-        (i.e. the contents of <literal>/var</literal>) is reset at boot and lost at shutdown.</para>
+        <para>If set to <option>state</option> the generator will leave the root directory mount point unaltered,
+        however will mount a <literal>tmpfs</literal> file system to <filename>/var</filename>. In this mode the normal
+        system configuration (i.e. the contents of <literal>/etc</literal>) is in effect (and may be modified during
+        system runtime), however the system state (i.e. the contents of <literal>/var</literal>) is reset at boot and
+        lost at shutdown.</para>
+
+        <para>If this setting is set to <literal>overlay</literal> the root file system is set up as
+        <literal>overlayfs</literal> mount combining the read-only root directory with a writable
+        <literal>tmpfs</literal>, so that no modifications are made to disk, but the file system may be modified
+        nonetheless with all changes being lost at reboot.</para>
 
         <para>Note that in none of these modes the root directory, <filename>/etc</filename>, <filename>/var</filename>
         or any other resources stored in the root file system are physically removed. It's thus safe to boot a system
         that is normally operated in non-volatile mode temporarily into volatile mode, without losing data.</para>
 
-        <para>Note that enabling this setting will only work correctly on operating systems that can boot up with only
-        <filename>/usr</filename> mounted, and are able to automatically populate <filename>/etc</filename>, and also
-        <filename>/var</filename> in case of <literal>systemd.volatile=yes</literal>.</para></listitem>
+        <para>Note that with the exception of <literal>overlay</literal> mode, enabling this setting will only work
+        correctly on operating systems that can boot up with only <filename>/usr</filename> mounted, and are able to
+        automatically populate <filename>/etc</filename>, and also <filename>/var</filename> in case of
+        <literal>systemd.volatile=yes</literal>.</para></listitem>
       </varlistentry>
     </variablelist>
   </refsect1>