mirror of
https://github.com/systemd/systemd
synced 2024-07-22 18:55:10 +00:00
0c69794138
These lines are generally out-of-date, incomplete and unnecessary. With SPDX and git repository much more accurate and fine grained information about licensing and authorship is available, hence let's drop the per-file copyright notice. Of course, removing copyright lines of others is problematic, hence this commit only removes my own lines and leaves all others untouched. It might be nicer if sooner or later those could go away too, making git the only and accurate source of authorship information.
160 lines
7.3 KiB
XML
160 lines
7.3 KiB
XML
<?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">
|
|
|
|
<!--
|
|
SPDX-License-Identifier: LGPL-2.1+
|
|
-->
|
|
|
|
<refentry id="sd_id128_get_machine" xmlns:xi="http://www.w3.org/2001/XInclude">
|
|
|
|
<refentryinfo>
|
|
<title>sd_id128_get_machine</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_get_machine</refentrytitle>
|
|
<manvolnum>3</manvolnum>
|
|
</refmeta>
|
|
|
|
<refnamediv>
|
|
<refname>sd_id128_get_machine</refname>
|
|
<refname>sd_id128_get_machine_app_specific</refname>
|
|
<refname>sd_id128_get_boot</refname>
|
|
<refname>sd_id128_get_invocation</refname>
|
|
<refpurpose>Retrieve 128-bit IDs</refpurpose>
|
|
</refnamediv>
|
|
|
|
<refsynopsisdiv>
|
|
<funcsynopsis>
|
|
<funcsynopsisinfo>#include <systemd/sd-id128.h></funcsynopsisinfo>
|
|
|
|
<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_machine_app_specific</function></funcdef>
|
|
<paramdef>sd_id128_t <parameter>app_id</parameter></paramdef>
|
|
<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>
|
|
|
|
<funcprototype>
|
|
<funcdef>int <function>sd_id128_get_invocation</function></funcdef>
|
|
<paramdef>sd_id128_t *<parameter>ret</parameter></paramdef>
|
|
</funcprototype>
|
|
|
|
</funcsynopsis>
|
|
</refsynopsisdiv>
|
|
|
|
<refsect1>
|
|
<title>Description</title>
|
|
|
|
<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. This ID
|
|
may be used wherever a unique identifier for the local system is needed. However, it is recommended to use this ID
|
|
as-is only in trusted environments. In untrusted environments it is recommended to derive an application specific
|
|
ID from this machine ID, in an irreversable (cryptographically secure) way. To make this easy
|
|
<function>sd_id128_get_machine_app_specific()</function> is provided, see below.</para>
|
|
|
|
<para><function>sd_id128_get_machine_app_specific()</function> is similar to
|
|
<function>sd_id128_get_machine()</function>, but retrieves a machine ID that is specific to the application that is
|
|
identified by the indicated application ID. It is recommended to use this function instead of
|
|
<function>sd_id128_get_machine()</function> when passing an ID to untrusted environments, in order to make sure
|
|
that the original machine ID may not be determined externally. The application-specific ID should be generated via
|
|
a tool like <command>journalctl --new-id128</command>, and may be compiled into the application. This function will
|
|
return the same application-specific ID for each combination of machine ID and application ID. Internally, this
|
|
function calculates HMAC-SHA256 of the application ID, keyed by the machine ID.</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 project='man-pages'><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><function>sd_id128_get_invocation()</function> returns the invocation ID of the currently executed
|
|
service. In its current implementation, this reads and parses the <varname>$INVOCATION_ID</varname> environment
|
|
variable that the service manager sets when activating a service, see
|
|
<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> for details. The
|
|
ID is cached internally. In future a different mechanism to determine the invocation ID may be added.</para>
|
|
|
|
<para>Note that <function>sd_id128_get_machine_app_specific()</function>, <function>sd_id128_get_boot()</function>
|
|
and <function>sd_id128_get_invocation()</function> always return UUID v4 compatible IDs.
|
|
<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 a 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>3</manvolnum></citerefentry>.</para>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>Return Value</title>
|
|
|
|
<para>Those calls return 0 on success (in which case <parameter>ret</parameter> is filled in),
|
|
or a negative errno-style error code. In particular, <function>sd_id128_get_machine()</function>
|
|
and <function>sd_id128_get_machine_app_specific()</function> return <constant>-ENOENT</constant>
|
|
if <filename>/etc/machine-id</filename> is missing, and <constant>-ENOMEDIUM</constant> if is
|
|
empty or all zeros.</para>
|
|
</refsect1>
|
|
|
|
<xi:include href="libsystemd-pkgconfig.xml" />
|
|
|
|
<refsect1>
|
|
<title>Examples</title>
|
|
|
|
<example>
|
|
<title>Application-specific machine ID</title>
|
|
|
|
<para>Here's a simple example for an application specific machine ID:</para>
|
|
|
|
<programlisting>#include <systemd/sd-id128.h>
|
|
#include <stdio.h>
|
|
|
|
#define OUR_APPLICATION_ID SD_ID128_MAKE(c2,73,27,73,23,db,45,4e,a6,3b,b9,6e,79,b5,3e,97)
|
|
|
|
int main(int argc, char *argv[]) {
|
|
sd_id128_t id;
|
|
sd_id128_get_machine_app_specific(OUR_APPLICATION_ID, &id);
|
|
printf("Our application ID: " SD_ID128_FORMAT_STR "\n", SD_ID128_FORMAT_VAL(id));
|
|
return 0;
|
|
}</programlisting>
|
|
</example>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>See Also</title>
|
|
|
|
<para>
|
|
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
|
|
<citerefentry><refentrytitle>sd-id128</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
|
<citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
|
<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
|
<citerefentry><refentrytitle>sd_id128_randomize</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
|
<citerefentry project='man-pages'><refentrytitle>random</refentrytitle><manvolnum>4</manvolnum></citerefentry>
|
|
</para>
|
|
</refsect1>
|
|
|
|
</refentry>
|