summaryrefslogtreecommitdiff
path: root/man/sd_id128_randomize.xml
diff options
context:
space:
mode:
Diffstat (limited to 'man/sd_id128_randomize.xml')
-rw-r--r--man/sd_id128_randomize.xml157
1 files changed, 157 insertions, 0 deletions
diff --git a/man/sd_id128_randomize.xml b/man/sd_id128_randomize.xml
new file mode 100644
index 0000000000..499c55fb60
--- /dev/null
+++ b/man/sd_id128_randomize.xml
@@ -0,0 +1,157 @@
+<?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/>.
+-->
+
+<refentry id="sd_id128_randomize">
+
+ <refentryinfo>
+ <title>sd_id128_randomize</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_id128_randomize</refentrytitle>
+ <manvolnum>3</manvolnum>
+ </refmeta>
+
+ <refnamediv>
+ <refname>sd_id128_randomize</refname>
+ <refname>sd_id128_get_machine</refname>
+ <refname>sd_id128_get_boot</refname>
+ <refpurpose>Generate or retrieve 128 bit IDs</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+ <funcsynopsis>
+ <funcsynopsisinfo>#include &lt;systemd/sd-id128.h&gt;</funcsynopsisinfo>
+
+ <funcprototype>
+ <funcdef>int <function>sd_id128_randomize</function></funcdef>
+ <paramdef>sd_id128_t* <parameter>ret</parameter></paramdef>
+ </funcprototype>
+
+ <funcprototype>
+ <funcdef>int <function>sd_id128_get_machine</function></funcdef>
+ <paramdef>sd_id128_t* <parameter>ret</parameter></paramdef>
+ </funcprototype>
+
+ <funcprototype>
+ <funcdef>int <function>sd_id128_get_boot</function></funcdef>
+ <paramdef>sd_id128_t* <parameter>ret</parameter></paramdef>
+ </funcprototype>
+
+ </funcsynopsis>
+ </refsynopsisdiv>
+
+ <refsect1>
+ <title>Description</title>
+
+ <para><function>sd_id128_randomize()</function>
+ generates a new randomized 128 bit ID and returns it
+ in <parameter>ret</parameter>. Every invocation
+ returns a new randomly generated ID. This uses the
+ <filename>/dev/urandom</filename> kernel random number
+ generator.</para>
+
+ <para><function>sd_id128_get_machine()</function>
+ returns the machine ID of the executing host. This
+ reads and parses the
+ <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ file. This function caches the machine ID internally
+ to make retrieving the machine ID a cheap
+ operation.</para>
+
+ <para><function>sd_id128_get_boot()</function> returns
+ the boot ID of the executing kernel. This reads and
+ parses the
+ <filename>/proc/sys/kernel/random/boot_id</filename>
+ file exposed by the kernel. It is randomly generated
+ early at boot and is unique for every running kernel
+ instance. See
+ <citerefentry><refentrytitle>random</refentrytitle><manvolnum>4</manvolnum></citerefentry>
+ for more information. This function also internally
+ caches the returned ID to make this call a cheap
+ operation.</para>
+
+ <para>Note that
+ <function>sd_id128_randomize()</function> and
+ <function>sd_id128_get_boot()</function> always return
+ a UUID v4 compatible
+ ID. <function>sd_id128_get_machine()</function> will
+ also return a UUID v4 compatible ID on new
+ installations, but might not on older. It is possible
+ to convert the machine ID into an UUID v4 compatible
+ one. For more information see
+ <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
+
+ <para>For more information about the
+ <literal>sd_id128_t</literal> type see
+ <citerefentry><refentrytitle>sd-id128</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
+
+ <para><citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
+ <literal>--new-id</literal> command may be used as
+ command line front-end for
+ <function>sd_id128_randomize()</function>.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>Return Value</title>
+
+ <para>The three calls returns 0 on success (in which
+ case <parameter>ret</parameter> is filled in), or a
+ negative errno-style error code.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>Notes</title>
+
+ <para>The <function>sd_id128_randomize()</function>,
+ <function>sd_id128_get_machine()</function> and
+ <function>sd_id128_get_boot()</function> interfaces
+ are available as shared library, which can be compiled
+ and linked to with the
+ <literal>libsystemd-id128</literal>
+ <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+ file.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>See Also</title>
+
+ <para>
+ <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd-id128</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>random</refentrytitle><manvolnum>4</manvolnum></citerefentry>
+ </para>
+ </refsect1>
+
+</refentry>