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authorLennart Poettering <lennart@poettering.net>2016-08-31 12:23:27 +0200
committerLennart Poettering <lennart@poettering.net>2016-10-07 20:14:38 +0200
commit3dbea941d2ee2700eb5e42c8b8352c841e9e0d96 (patch)
tree31deaddf04fb227deac1b0182f9546b0ee5bdc36 /man/sd-id128.xml
parent4b58153dd22172d817055d2a09a0cdf3f4bd9db3 (diff)
man: update sd-id128(3) a bit
Let's add documentation about SD_ID128_NULL and sd_id128_is_null(). Let's also indent our examples by 8chs, as is generally our coding style.
Diffstat (limited to 'man/sd-id128.xml')
-rw-r--r--man/sd-id128.xml41
1 files changed, 26 insertions, 15 deletions
diff --git a/man/sd-id128.xml b/man/sd-id128.xml
index ea7972055d..5f24feff8e 100644
--- a/man/sd-id128.xml
+++ b/man/sd-id128.xml
@@ -47,10 +47,12 @@
<refname>sd-id128</refname>
<refname>sd_id128_t</refname>
<refname>SD_ID128_MAKE</refname>
+ <refname>SD_ID128_NULL</refname>
<refname>SD_ID128_CONST_STR</refname>
<refname>SD_ID128_FORMAT_STR</refname>
<refname>SD_ID128_FORMAT_VAL</refname>
<refname>sd_id128_equal</refname>
+ <refname>sd_id128_is_null</refname>
<refpurpose>APIs for processing 128-bit IDs</refpurpose>
</refnamediv>
@@ -88,8 +90,8 @@
union type:</para>
<programlisting>typedef union sd_id128 {
- uint8_t bytes[16];
- uint64_t qwords[2];
+ uint8_t bytes[16];
+ uint64_t qwords[2];
} sd_id128_t;</programlisting>
<para>This union type allows accessing the 128-bit ID as 16
@@ -108,37 +110,46 @@
<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_NULL</function> may be used to refer to the 128bit ID consisting of only NUL
+ bytes.</para>
+
<para><function>SD_ID128_CONST_STR()</function> may be used to
convert constant 128-bit IDs into constant strings for output. The
following example code will output the string
"fc2e22bc6ee647b6b90729ab34a250b1":</para>
<programlisting>int main(int argc, char *argv[]) {
- puts(SD_ID128_CONST_STR(SD_MESSAGE_COREDUMP));
+ puts(SD_ID128_CONST_STR(SD_MESSAGE_COREDUMP));
}</programlisting>
- <para><function>SD_ID128_FORMAT_STR</function> and
+ <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 project='man-pages'><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;
+ 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;
+ 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>Use <function>sd_id128_is_null()</function> to check if an 128bit ID consists of only NUL bytes:</para>
+
+ <programlisting>int main(int argc, char *argv[]) {
+ assert(sd_id128_is_null(SD_ID128_NULL));
}</programlisting>
<para>Note that new, randomized IDs may be generated with