Commit 12355095 authored by Lennart Poettering's avatar Lennart Poettering
Browse files

man: document libsystemd-id128

parent 97595710
......@@ -501,7 +501,10 @@ MANPAGES = \
man/systemd-getty-generator.8 \
man/systemd-system-update-generator.8 \
man/systemd-fstab-generator.8 \
man/systemd.preset.5
man/systemd.preset.5 \
man/sd-id128.7 \
man/sd_id128_to_string.3 \
man/sd_id128_randomize.3
MANPAGES_ALIAS = \
man/reboot.8 \
......@@ -530,7 +533,15 @@ MANPAGES_ALIAS = \
man/systemd-ask-password-wall.path.8 \
man/systemd-tmpfiles-setup.service.8 \
man/systemd-tmpfiles-clean.service.8 \
man/systemd-tmpfiles-clean.timer.8
man/systemd-tmpfiles-clean.timer.8 \
man/sd_id128_t.7 \
man/SD_ID128_MAKE.7 \
man/SD_ID128_FORMAT_STR.7 \
man/SD_ID128_FORMAT_VAL.7 \
man/sd_id128_equal.7 \
man/sd_id128_from_string.3 \
man/sd_id128_get_machine.3 \
man/sd_id128_get_boot.3
man/reboot.8: man/halt.8
man/poweroff.8: man/halt.8
......@@ -559,6 +570,14 @@ man/systemd-ask-password-wall.path.8: man/systemd-ask-password-console.service.8
man/systemd-tmpfiles-setup.service.8: man/systemd-tmpfiles.8
man/systemd-tmpfiles-clean.service.8: man/systemd-tmpfiles.8
man/systemd-tmpfiles-clean.timer.8: man/systemd-tmpfiles.8
man/sd_id128_t.7: man/sd-id128.7
man/SD_ID128_MAKE.7: man/sd-id128.7
man/SD_ID128_FORMAT_STR.7: man/sd-id128.7
man/SD_ID128_FORMAT_VAL.7: man/sd-id128.7
man/sd_id128_equal.7: man/sd-id128.7
man/sd_id128_from_string.3: man/sd_id128_to_string.3
man/sd_id128_get_machine.3: man/sd_id128_randomize.3
man/sd_id128_get_boot.3: man/sd_id128_randomize.3
XML_FILES = \
${patsubst %.1,%.xml,${patsubst %.3,%.xml,${patsubst %.5,%.xml,${patsubst %.7,%.xml,${patsubst %.8,%.xml,$(MANPAGES)}}}}}
......
......@@ -22,6 +22,10 @@ Bugfixes:
Features:
* journalctl highlight reboots
* Merge KillUnit()'s mode and who params into one
* load-fragment: when loading a unit file via a chain of symlinks
verify that it isn't masked via any of the names traversed.
......
......@@ -136,7 +136,9 @@ id[8] = (id[8] &amp; 0x3F) | 0x80;</programlisting>
<citerefentry><refentrytitle>gethostid</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>hostname</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>machine-info</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>os-release</refentrytitle><manvolnum>5</manvolnum></citerefentry>
<citerefentry><refentrytitle>os-release</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd-id128</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_id128_get_machine</refentrytitle><manvolnum>3</manvolnum></citerefentry>
</para>
</refsect1>
......
<?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">
<refentryinfo>
<title>sd-id128</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</refentrytitle>
<manvolnum>7</manvolnum>
</refmeta>
<refnamediv>
<refname>sd-id128</refname>
<refname>sd_id128_t</refname>
<refname>SD_ID128_MAKE</refname>
<refname>SD_ID128_FORMAT_STR</refname>
<refname>SD_ID128_FORMAT_VAL</refname>
<refname>sd_id128_equal</refname>
<refpurpose>APIs for processing 128 bit IDs</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>#include &lt;systemd/sd-id128.h&gt;</funcsynopsisinfo>
</funcsynopsis>
<cmdsynopsis>
<command>pkg-config --cflags --libs libsystemd-id128</command>
</cmdsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><filename>sd-id128.h</filename> provides APIs to
process and generate 128 bit ID values. The 128 bit ID
values processed and generated by these APIs are a
generalization of OSF UUIDs as defined by <ulink
url="http://tools.ietf.org/html/rfc4122">RFC
4122</ulink>, though use a simpler string
formatting. These functions impose no structure on the
used IDs, much unlike OSF UUIDs or Microsoft GUIDs,
but are fully compatible with those types of IDs.
</para>
<para>See
<citerefentry><refentrytitle>sd_id128_to_string</refentrytitle><manvolnum>3</manvolnum></citerefentry> and
<citerefentry><refentrytitle>sd_id128_randomize</refentrytitle><manvolnum>3</manvolnum></citerefentry>
for more information about the functions
implemented.</para>
<para>A 128 bit ID is implemented as the following
union type:</para>
<programlisting>typedef union sd_id128 {
uint8_t bytes[16];
uint64_t qwords[2];
} sd_id128_t;</programlisting>
<para>This union type allows accessing the 128 bit ID
as 16 separate bytes or 2 64 bit words. It is generally
safer to access the ID components by their 8 bit array
to avoid endianess issues. This union is intended to
be passed call-by-value (as opposed to
call-by-reference) and may be directly manipulated by
clients.</para>
<para>A couple of macros are defined to denote and
decode 128 bit IDs:</para>
<para><function>SD_ID128_MAKE()</function> may be used
to write a 128 bit ID in source code. A commonly used
idiom is to give 128 bit IDs names using this macro:</para>
<programlisting>#define SD_MESSAGE_COREDUMP SD_ID128_MAKE(fc,2e,22,bc,6e,e6,47,b6,b9,07,29,ab,34,a2,50,b1)</programlisting>
<para><function>SD_ID128_FORMAT_STR</function> and
<function>SD_ID128_FORMAT_VAL()</function> may be used
to format a 128 bit ID in a
<citerefentry><refentrytitle>printf</refentrytitle><manvolnum>3</manvolnum></citerefentry>
format string, as shown in the following
example:</para>
<programlisting>int main(int argc, char *argv[]) {
sd_id128_t id;
id = SD_ID128_MAKE(ee,89,be,71,bd,6e,43,d6,91,e6,c5,5d,eb,03,02,07);
printf("The ID encoded in this C file is " SD_ID128_FORMAT_STR ".\n", SD_ID128_FORMAT_VAL(id));
return 0;
}</programlisting>
<para>Use <function>sd_id128_equal()</function> to compare two 128 bit IDs:</para>
<programlisting>int main(int argc, char *argv[]) {
sd_id128_t a, b, c;
a = SD_ID128_MAKE(ee,89,be,71,bd,6e,43,d6,91,e6,c5,5d,eb,03,02,07);
b = SD_ID128_MAKE(f2,28,88,9c,5f,09,44,15,9d,d7,04,77,58,cb,e7,3e);
c = a;
assert(sd_id128_equal(a, c));
assert(!sd_id128_equal(a, b));
return 0;
}</programlisting>
<para>Note that new, randomized IDs may be generated
with
<citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
<literal>--new-id</literal> command.</para>
</refsect1>
<refsect1>
<title>Notes</title>
<para>These APIs are implemented 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_to_string</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_id128_randomize</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>printf</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
<citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>
<?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>
<?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_to_string">
<refentryinfo>
<title>sd_id128_to_string</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_to_string</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>sd_id128_to_string</refname>
<refname>sd_id128_from_string</refname>
<refpurpose>Format or parse 128 bit IDs as strings</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>#include &lt;systemd/sd-id128.h&gt;</funcsynopsisinfo>
<funcprototype>
<funcdef>char* <function>sd_id128_to_string</function></funcdef>
<paramdef>sd_id128_t <parameter>id</parameter>, char <parameter>s</parameter>[33]</paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_id128_from_string</function></funcdef>
<paramdef>const char <parameter>s</parameter>[33], sd_id128_t* <parameter>ret</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><function>sd_id128_to_string()</function>
formats a 128 bit ID as character string. It expects
the ID and a string array capable of storing 33
characters. The ID will be formatted as 32 lowercase
hexadecimal digits and be terminated by a NUL
byte.</para>
<para><function>sd_id128_from_string()</function>
implements the reverse operation: it takes a 33
character array with 32 hexadecimial digits
(terminated by NUL) and parses them back into an
128 bit ID returned in
<parameter>ret</parameter>.</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>When formatting a 128 bit ID into a string it is
often easier to use a format string for
<citerefentry><refentrytitle>printf</refentrytitle><manvolnum>3</manvolnum></citerefentry>. This
is easly done using the
<function>SD_ID128_FORMAT_STR</function> and
<function>SD_ID128_FORMAT_VAL()</function> macros. For
more information see
<citerefentry><refentrytitle>sd-id128</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
</refsect1>
<refsect1>
<title>Return Value</title>
<para><function>sd_id128_to_string()</function> always
succeeds and returns a pointer to the string array
passed in. <function>sd_id128_from_string</function>
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_to_string()</function>
and <function>sd_id128_from_string()</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>printf</refentrytitle><manvolnum>3</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>
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