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12355095 | 1 | <?xml version='1.0'?> <!--*-nxml-*--> |
3a54a157 | 2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" |
eea10b26 | 3 | "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd"> |
db9ecf05 | 4 | <!-- SPDX-License-Identifier: LGPL-2.1-or-later --> |
12355095 | 5 | |
6a70f3aa | 6 | <refentry id="sd-id128" |
798d3a52 ZJS |
7 | xmlns:xi="http://www.w3.org/2001/XInclude"> |
8 | ||
9 | <refentryinfo> | |
10 | <title>sd-id128</title> | |
11 | <productname>systemd</productname> | |
798d3a52 ZJS |
12 | </refentryinfo> |
13 | ||
14 | <refmeta> | |
15 | <refentrytitle>sd-id128</refentrytitle> | |
16 | <manvolnum>3</manvolnum> | |
17 | </refmeta> | |
18 | ||
19 | <refnamediv> | |
20 | <refname>sd-id128</refname> | |
78aa5b6f ZJS |
21 | <refname>SD_ID128_ALLF</refname> |
22 | <refname>SD_ID128_CONST_STR</refname> | |
23 | <refname>SD_ID128_FORMAT_STR</refname> | |
24 | <refname>SD_ID128_FORMAT_VAL</refname> | |
798d3a52 | 25 | <refname>SD_ID128_MAKE</refname> |
2b044526 | 26 | <refname>SD_ID128_MAKE_STR</refname> |
7c7683f3 | 27 | <refname>SD_ID128_MAKE_UUID_STR</refname> |
3dbea941 | 28 | <refname>SD_ID128_NULL</refname> |
38df8d3f | 29 | <refname>SD_ID128_UUID_FORMAT_STR</refname> |
798d3a52 | 30 | <refname>sd_id128_equal</refname> |
944c1243 | 31 | <refname>sd_id128_string_equal</refname> |
64b21afc ZJS |
32 | <refname>sd_id128_in_set</refname> |
33 | <refname>sd_id128_in_set_sentinel</refname> | |
34 | <refname>sd_id128_in_setv</refname> | |
78aa5b6f | 35 | <refname>sd_id128_is_allf</refname> |
3dbea941 | 36 | <refname>sd_id128_is_null</refname> |
78aa5b6f | 37 | <refname>sd_id128_t</refname> |
798d3a52 ZJS |
38 | <refpurpose>APIs for processing 128-bit IDs</refpurpose> |
39 | </refnamediv> | |
40 | ||
41 | <refsynopsisdiv> | |
42 | <funcsynopsis> | |
43 | <funcsynopsisinfo>#include <systemd/sd-id128.h></funcsynopsisinfo> | |
d13f1051 ZJS |
44 | |
45 | <para> | |
46 | <constant>SD_ID128_ALLF</constant> | |
47 | </para> | |
48 | <para> | |
49 | <constant>SD_ID128_NULL</constant> | |
50 | </para> | |
51 | <para> | |
52 | <constant>SD_ID128_CONST_STR(<replaceable>id</replaceable>)</constant> | |
53 | </para> | |
54 | <para> | |
55 | <constant>SD_ID128_FORMAT_STR</constant> | |
56 | </para> | |
57 | <para> | |
58 | <constant>SD_ID128_FORMAT_VAL(<replaceable>id</replaceable>)</constant> | |
59 | </para> | |
60 | <para> | |
61 | <constant>SD_ID128_MAKE(<replaceable>v0</replaceable>, <replaceable>v1</replaceable>, <replaceable>v2</replaceable>, <replaceable>v3</replaceable>, <replaceable>v4</replaceable>, <replaceable>v5</replaceable>, <replaceable>v6</replaceable>, <replaceable>v7</replaceable>, <replaceable>v8</replaceable>, <replaceable>v9</replaceable>, <replaceable>vA</replaceable>, <replaceable>vB</replaceable>, <replaceable>vC</replaceable>, <replaceable>vD</replaceable>, <replaceable>vE</replaceable>, <replaceable>vF</replaceable>)</constant> | |
62 | </para> | |
63 | <para> | |
64 | <constant>SD_ID128_MAKE_STR(<replaceable>v0</replaceable>, <replaceable>v1</replaceable>, <replaceable>v2</replaceable>, <replaceable>v3</replaceable>, <replaceable>v4</replaceable>, <replaceable>v5</replaceable>, <replaceable>v6</replaceable>, <replaceable>v7</replaceable>, <replaceable>v8</replaceable>, <replaceable>v9</replaceable>, <replaceable>vA</replaceable>, <replaceable>vB</replaceable>, <replaceable>vC</replaceable>, <replaceable>vD</replaceable>, <replaceable>vE</replaceable>, <replaceable>vF</replaceable>)</constant> | |
65 | </para> | |
66 | <para> | |
67 | <constant>SD_ID128_MAKE_UUID_STR(<replaceable>v0</replaceable>, <replaceable>v1</replaceable>, <replaceable>v2</replaceable>, <replaceable>v3</replaceable>, <replaceable>v4</replaceable>, <replaceable>v5</replaceable>, <replaceable>v6</replaceable>, <replaceable>v7</replaceable>, <replaceable>v8</replaceable>, <replaceable>v9</replaceable>, <replaceable>vA</replaceable>, <replaceable>vB</replaceable>, <replaceable>vC</replaceable>, <replaceable>vD</replaceable>, <replaceable>vE</replaceable>, <replaceable>vF</replaceable>)</constant> | |
68 | </para> | |
69 | <para> | |
70 | <constant>SD_ID128_UUID_FORMAT_STR</constant> | |
71 | </para> | |
72 | ||
73 | <funcprototype> | |
74 | <funcdef>int <function>sd_id128_equal</function></funcdef> | |
75 | <paramdef>sd_id128_t <parameter>a</parameter></paramdef> | |
76 | <paramdef>sd_id128_t <parameter>b</parameter></paramdef> | |
77 | </funcprototype> | |
78 | ||
944c1243 ZJS |
79 | <funcprototype> |
80 | <funcdef>int <function>sd_id128_string_equal</function></funcdef> | |
81 | <paramdef>const char *<parameter>a</parameter></paramdef> | |
82 | <paramdef>sd_id128_t <parameter>b</parameter></paramdef> | |
83 | </funcprototype> | |
84 | ||
d13f1051 ZJS |
85 | <funcprototype> |
86 | <funcdef>int <function>sd_id128_is_null</function></funcdef> | |
87 | <paramdef>sd_id128_t <parameter>id</parameter></paramdef> | |
88 | </funcprototype> | |
89 | ||
90 | <funcprototype> | |
91 | <funcdef>int <function>sd_id128_is_allf</function></funcdef> | |
92 | <paramdef>sd_id128_t <parameter>id</parameter></paramdef> | |
93 | </funcprototype> | |
94 | ||
95 | <funcprototype> | |
96 | <funcdef>int <function>sd_id128_in_setv</function></funcdef> | |
97 | <paramdef>sd_id128_t <parameter>id</parameter></paramdef> | |
98 | <paramdef>va_list <parameter>ap</parameter></paramdef> | |
99 | </funcprototype> | |
100 | ||
101 | <funcprototype> | |
102 | <funcdef>int <function>sd_id128_in_set_sentinel</function></funcdef> | |
103 | <paramdef>sd_id128_t <parameter>id</parameter></paramdef> | |
104 | <paramdef>…</paramdef> | |
3c2b711f | 105 | <paramdef><parameter><constant>SD_ID128_NULL</constant></parameter></paramdef> |
d13f1051 ZJS |
106 | </funcprototype> |
107 | ||
108 | <funcprototype> | |
109 | <funcdef>int <function>sd_id128_in_set</function></funcdef> | |
110 | <paramdef>sd_id128_t <parameter>id</parameter></paramdef> | |
111 | <paramdef>…</paramdef> | |
112 | </funcprototype> | |
798d3a52 ZJS |
113 | </funcsynopsis> |
114 | ||
115 | <cmdsynopsis> | |
116 | <command>pkg-config --cflags --libs libsystemd</command> | |
117 | </cmdsynopsis> | |
118 | ||
119 | </refsynopsisdiv> | |
120 | ||
121 | <refsect1> | |
122 | <title>Description</title> | |
123 | ||
4bc96dc1 ZJS |
124 | <para><filename>sd-id128.h</filename> is part of |
125 | <citerefentry><refentrytitle>libsystemd</refentrytitle><manvolnum>3</manvolnum></citerefentry> and | |
126 | provides APIs to generate, convert, and compare 128-bit ID values. The 128-bit ID values processed and | |
127 | generated by these APIs are a generalization of OSF UUIDs as defined by <ulink | |
128 | url="https://tools.ietf.org/html/rfc4122">RFC 4122</ulink> but use a simpler string format. These | |
129 | functions impose no structure on the used IDs, much unlike OSF UUIDs or Microsoft GUIDs, but are mostly | |
130 | compatible with those types of IDs. | |
798d3a52 ZJS |
131 | </para> |
132 | ||
798d3a52 ZJS |
133 | <para>A 128-bit ID is implemented as the following |
134 | union type:</para> | |
135 | ||
136 | <programlisting>typedef union sd_id128 { | |
e0a41aa4 ZJS |
137 | uint8_t bytes[16]; |
138 | uint64_t qwords[2]; | |
12355095 LP |
139 | } sd_id128_t;</programlisting> |
140 | ||
d13f1051 ZJS |
141 | <para>This union type allows accessing the 128-bit ID as 16 separate bytes or two 64-bit words. It is |
142 | generally safer to access the ID components by their 8-bit array to avoid endianness issues. This union | |
143 | is intended to be passed by value (as opposed to pass-by-reference) and may be directly manipulated by | |
798d3a52 ZJS |
144 | clients.</para> |
145 | ||
146 | <para>A couple of macros are defined to denote and decode 128-bit | |
147 | IDs:</para> | |
148 | ||
d13f1051 ZJS |
149 | <para><function>SD_ID128_MAKE()</function> is used to write a constant ID in source code. A commonly used |
150 | idiom is to assign a name to an ID using this macro:</para> | |
798d3a52 ZJS |
151 | |
152 | <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> | |
153 | ||
d13f1051 ZJS |
154 | <para><constant>SD_ID128_NULL</constant> defines an ID consisting of only <constant>NUL</constant> bytes |
155 | (i.e. all bits off).</para> | |
7f3c90ed | 156 | |
d13f1051 ZJS |
157 | <para><constant>SD_ID128_ALLF</constant> defines an ID consisting of only <constant>0xFF</constant> bytes |
158 | (i.e. all bits on).</para> | |
3dbea941 | 159 | |
d13f1051 ZJS |
160 | <para><function>SD_ID128_MAKE_STR()</function> is similar to <function>SD_ID128_MAKE()</function>, but |
161 | creates a <type>const char*</type> expression that can be conveniently used in message formats and | |
162 | such:</para> | |
2b044526 ZJS |
163 | |
164 | <programlisting>#include <stdio.h> | |
165 | #define SD_MESSAGE_COREDUMP_STR SD_ID128_MAKE_STR(fc,2e,22,bc,6e,e6,47,b6,b9,07,29,ab,34,a2,50,b1) | |
166 | ||
167 | int main(int argc, char **argv) { | |
e0a41aa4 | 168 | puts("Match for coredumps: MESSAGE_ID=" SD_MESSAGE_COREDUMP_STR); |
39d02a17 | 169 | }</programlisting> |
2b044526 | 170 | |
d13f1051 ZJS |
171 | <para><function>SD_ID128_CONST_STR()</function> converts constant IDs into constant strings for |
172 | output. The following example code will output the string "fc2e22bc6ee647b6b90729ab34a250b1":</para> | |
798d3a52 | 173 | <programlisting>int main(int argc, char *argv[]) { |
e0a41aa4 | 174 | puts("Match for coredumps: %s", SD_ID128_CONST_STR(SD_MESSAGE_COREDUMP)); |
183de6d7 LP |
175 | }</programlisting> |
176 | ||
d13f1051 ZJS |
177 | <para><constant>SD_ID128_FORMAT_STR</constant> and <function>SD_ID128_FORMAT_VAL()</function> is used to |
178 | format an ID in a <citerefentry | |
179 | project='man-pages'><refentrytitle>printf</refentrytitle><manvolnum>3</manvolnum></citerefentry> format | |
180 | string, as shown in the following example:</para> | |
798d3a52 ZJS |
181 | |
182 | <programlisting>int main(int argc, char *argv[]) { | |
e0a41aa4 ZJS |
183 | sd_id128_t id; |
184 | id = SD_ID128_MAKE(ee,89,be,71,bd,6e,43,d6,91,e6,c5,5d,eb,03,02,07); | |
185 | printf("The ID encoded in this C file is " SD_ID128_FORMAT_STR ".\n", SD_ID128_FORMAT_VAL(id)); | |
186 | return 0; | |
12355095 LP |
187 | }</programlisting> |
188 | ||
7c7683f3 ZJS |
189 | <para><constant>SD_ID128_UUID_FORMAT_STR</constant> and <function>SD_ID128_MAKE_UUID_STR()</function> |
190 | are similar to | |
191 | <constant>SD_ID128_FORMAT_STR</constant> and <function>SD_ID128_MAKE_STR()</function>, | |
192 | but include separating hyphens to conform to the | |
c8cd6d7b | 193 | "<ulink url="https://en.wikipedia.org/wiki/Universally_unique_identifier#Format">UUID canonical representation</ulink>". |
7c7683f3 | 194 | They format the string based on <ulink |
39d02a17 LP |
195 | url="https://tools.ietf.org/html/rfc4122">RFC4122</ulink> Variant 1 rules, i.e. converting from Big |
196 | Endian byte order. This matches behaviour of most other Linux userspace infrastructure. It's probably | |
197 | best to avoid UUIDs of other variants, in order to avoid unnecessary ambiguities. All 128-bit IDs | |
198 | generated by the sd-id128 APIs strictly conform to Variant 1 Version 4 UUIDs, as per RFC 4122.</para> | |
38df8d3f | 199 | |
d13f1051 | 200 | <para><function>sd_id128_equal()</function> compares two 128-bit IDs:</para> |
12355095 | 201 | |
798d3a52 | 202 | <programlisting>int main(int argc, char *argv[]) { |
e0a41aa4 ZJS |
203 | sd_id128_t a, b, c; |
204 | a = SD_ID128_MAKE(ee,89,be,71,bd,6e,43,d6,91,e6,c5,5d,eb,03,02,07); | |
205 | b = SD_ID128_MAKE(f2,28,88,9c,5f,09,44,15,9d,d7,04,77,58,cb,e7,3e); | |
206 | c = a; | |
207 | assert(sd_id128_equal(a, c)); | |
208 | assert(!sd_id128_equal(a, b)); | |
209 | return 0; | |
3dbea941 LP |
210 | }</programlisting> |
211 | ||
944c1243 ZJS |
212 | <para><function>sd_id128_string_equal()</function> is similar to <function>sd_id128_equal()</function>, |
213 | but the first ID is formatted as <type>const char*</type>. The same restrictions apply as to the first | |
214 | argument of <function>sd_id128_from_string()</function>.</para> | |
215 | ||
d13f1051 ZJS |
216 | <para><function>sd_id128_is_null()</function> checks if an ID consists of only <constant>NUL</constant> |
217 | bytes:</para> | |
3dbea941 | 218 | |
78aa5b6f ZJS |
219 | <programlisting>assert(sd_id128_is_null(SD_ID128_NULL));</programlisting> |
220 | ||
d13f1051 | 221 | <para>Similarly, <function>sd_id128_is_allf()</function> checks if an ID consists of only |
78aa5b6f ZJS |
222 | <constant>0xFF</constant> bytes (all bits on):</para> |
223 | ||
224 | <programlisting>assert(sd_id128_is_allf(SD_ID128_ALLF));</programlisting> | |
12355095 | 225 | |
d13f1051 ZJS |
226 | <para><function>sd_id128_in_set_sentinel()</function> takes a list of IDs and returns true if the first |
227 | argument is equal to any of the subsequent arguments. The argument list is terminated by an | |
228 | <constant>SD_ID128_NULL</constant> sentinel, which must be present.</para> | |
229 | ||
230 | <para><function>sd_id128_in_set()</function> is a convenience function that takes a list of IDs and | |
231 | returns true if the first argument is equal to any of the subsequent arguments:</para> | |
64b21afc ZJS |
232 | |
233 | <programlisting>int main(int argc, char *argv[]) { | |
234 | sd_id12_t a = SD_ID128_MAKE(ee,89,be,71,bd,6e,43,d6,91,e6,c5,5d,eb,03,02,07); | |
235 | assert(sd_id128_in_set(a, a)); | |
236 | assert(sd_id128_in_set(a, a, a)); | |
237 | assert(!sd_id128_in_set(a)); | |
238 | assert(!sd_id128_in_set(a, | |
239 | SD_ID128_MAKE(f2,28,88,9c,5f,09,44,15,9d,d7,04,77,58,cb,e7,3e) | |
240 | SD_ID128_MAKE(2f,88,28,5f,9c,44,09,9d,d7,15,77,04,bc,85,7e,e3) | |
241 | SD_ID128_ALLF)); | |
242 | return 0; | |
243 | } | |
244 | </programlisting> | |
245 | ||
246 | <para><function>sd_id128_in_set()</function> is defined as a macro over | |
d13f1051 ZJS |
247 | <function>sd_id128_in_set_sentinel()</function>, adding the <constant>SD_ID128_NULL</constant> sentinel |
248 | automatically. Since <function>sd_id128_in_set_sentinel()</function> uses | |
249 | <constant>SD_ID128_NULL</constant> as the sentinel, <constant>SD_ID128_NULL</constant> cannot be | |
250 | otherwise placed in the argument list.</para> | |
64b21afc ZJS |
251 | |
252 | <para><function>sd_id128_in_setv()</function> is similar to | |
253 | <function>sd_id128_in_set_sentinel()</function>, but takes a <structname>struct varargs</structname> | |
254 | argument.</para> | |
255 | ||
d13f1051 | 256 | <para>New randomized IDs may be generated with |
b9d016d6 LP |
257 | <citerefentry><refentrytitle>systemd-id128</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s |
258 | <command>new</command> command.</para> | |
d13f1051 ZJS |
259 | |
260 | <para>See | |
261 | <citerefentry><refentrytitle>sd_id128_to_string</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
262 | <citerefentry><refentrytitle>sd_id128_randomize</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
263 | and | |
264 | <citerefentry><refentrytitle>sd_id128_get_machine</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
265 | for information about other implemented functions.</para> | |
798d3a52 ZJS |
266 | </refsect1> |
267 | ||
268 | <xi:include href="libsystemd-pkgconfig.xml" /> | |
269 | ||
69106f47 AK |
270 | <refsect1> |
271 | <title>History</title> | |
00f95506 AK |
272 | <para><function>sd_id128_equal()</function>, |
273 | <function>sd_id128_string_equal()</function>, | |
274 | <function>sd_id128_is_null()</function>, | |
275 | <function>sd_id128_is_allf()</function>, | |
276 | <function>sd_id128_in_setv()</function>, | |
277 | <function>sd_id128_in_set_sentinel()</function>, and | |
278 | <function>sd_id128_in_set()</function> were added in version 252.</para> | |
69106f47 AK |
279 | </refsect1> |
280 | ||
798d3a52 ZJS |
281 | <refsect1> |
282 | <title>See Also</title> | |
13a69c12 DT |
283 | <para><simplelist type="inline"> |
284 | <member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member> | |
285 | <member><citerefentry><refentrytitle>sd_id128_to_string</refentrytitle><manvolnum>3</manvolnum></citerefentry></member> | |
286 | <member><citerefentry><refentrytitle>sd_id128_randomize</refentrytitle><manvolnum>3</manvolnum></citerefentry></member> | |
287 | <member><citerefentry><refentrytitle>sd_id128_get_machine</refentrytitle><manvolnum>3</manvolnum></citerefentry></member> | |
288 | <member><citerefentry project='man-pages'><refentrytitle>printf</refentrytitle><manvolnum>3</manvolnum></citerefentry></member> | |
289 | <member><citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry></member> | |
290 | <member><citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>7</manvolnum></citerefentry></member> | |
291 | <member><citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry></member> | |
292 | <member><citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry></member> | |
293 | </simplelist></para> | |
798d3a52 | 294 | </refsect1> |
12355095 LP |
295 | |
296 | </refentry> |