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diff --git a/man/sd_id128_to_string.xml b/man/sd_id128_to_string.xml new file mode 100644 index 0000000..e0338ba --- /dev/null +++ b/man/sd_id128_to_string.xml @@ -0,0 +1,122 @@ +<?xml version='1.0'?> <!--*-nxml-*--> +<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" + "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> +<!-- SPDX-License-Identifier: LGPL-2.1-or-later --> + +<refentry id="sd_id128_to_string" xmlns:xi="http://www.w3.org/2001/XInclude"> + + <refentryinfo> + <title>sd_id128_to_string</title> + <productname>systemd</productname> + </refentryinfo> + + <refmeta> + <refentrytitle>sd_id128_to_string</refentrytitle> + <manvolnum>3</manvolnum> + </refmeta> + + <refnamediv> + <refname>sd_id128_to_string</refname> + <refname>SD_ID128_TO_STRING</refname> + <refname>SD_ID128_STRING_MAX</refname> + <refname>sd_id128_to_uuid_string</refname> + <refname>SD_ID128_TO_UUID_STRING</refname> + <refname>SD_ID128_UUID_STRING_MAX</refname> + <refname>sd_id128_from_string</refname> + <refpurpose>Format or parse 128-bit IDs as strings</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcsynopsisinfo>#include <systemd/sd-id128.h></funcsynopsisinfo> + + <funcsynopsisinfo>#define SD_ID128_STRING_MAX 33U</funcsynopsisinfo> + + <funcsynopsisinfo>#define SD_ID128_UUID_STRING_MAX 37U</funcsynopsisinfo> + + <funcsynopsisinfo>#define SD_ID128_TO_STRING(id) …</funcsynopsisinfo> + + <funcsynopsisinfo>#define SD_ID128_TO_UUID_STRING(id) …</funcsynopsisinfo> + + <funcprototype> + <funcdef>char *<function>sd_id128_to_string</function></funcdef> + <paramdef>sd_id128_t <parameter>id</parameter>, char <parameter>s</parameter>[static SD_ID128_STRING_MAX]</paramdef> + </funcprototype> + + <funcprototype> + <funcdef>char *<function>sd_id128_uuid_string</function></funcdef> + <paramdef>sd_id128_t <parameter>id</parameter>, char <parameter>s</parameter>[static SD_ID128_UUID_STRING_MAX]</paramdef> + </funcprototype> + + <funcprototype> + <funcdef>int <function>sd_id128_from_string</function></funcdef> + <paramdef>const char *<parameter>s</parameter>, 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 a character string. It expects + the ID and a string array capable of storing 33 characters + (<constant>SD_ID128_STRING_MAX</constant>). The ID will be formatted as 32 lowercase hexadecimal digits + and be terminated by a <constant>NUL</constant> byte.</para> + + <para><function>SD_ID128_TO_STRING()</function> is a macro that wraps + <function>sd_id128_to_string()</function> and passes an appropriately sized buffer as second argument, + allocated as C99 compound literal. Each use will thus implicitly acquire a suitable buffer on the stack + which remains valid until the end of the current code block. This is usually the simplest way to acquire + a string representation of a 128-bit ID in a buffer that is valid in the current code block.</para> + + <para><function>sd_id128_to_uuid_string()</function> and <function>SD_ID128_TO_UUID_STRING()</function> + are similar to these two functions/macros, but format the 128bit values as RFC4122 UUIDs, i.e. a series + of 36 lowercase hexadeciaml digits and dashes, terminated by a <constant>NUL</constant> byte.</para> + + <para><function>sd_id128_from_string()</function> implements the reverse operation: it takes a 33 + character string with 32 hexadecimal digits (either lowercase or uppercase, terminated by + <constant>NUL</constant>) and parses them back into a 128-bit ID returned in + <parameter>ret</parameter>. Alternatively, this call can also parse a 37-character string with a 128-bit + ID formatted as RFC UUID. If <parameter>ret</parameter> is passed as <constant>NULL</constant> the + function will validate the passed ID string, but not actually return it in parsed form.</para> + + <para>Note that when formatting and parsing 36 character UUIDs this is done strictly in Big Endian byte order, + i.e. according to <ulink url="https://tools.ietf.org/html/rfc4122">RFC4122</ulink> Variant 1 rules, even + if the UUID encodes a different variant. This matches behaviour in various other Linux userspace + tools. It's probably wise to avoid UUIDs of other variant types.</para> + + <para>For more information about the <literal>sd_id128_t</literal> type see + <citerefentry><refentrytitle>sd-id128</refentrytitle><manvolnum>3</manvolnum></citerefentry>. Note that + these calls operate the same way on all architectures, i.e. the results do not depend on + endianness.</para> + + <para>When formatting a 128-bit ID into a string, it is often easier to use a format string for + <citerefentry + project='man-pages'><refentrytitle>printf</refentrytitle><manvolnum>3</manvolnum></citerefentry>. This + is easily done using the <constant>SD_ID128_FORMAT_STR</constant> and + <function>SD_ID128_FORMAT_VAL()</function> macros. For more information see + <citerefentry><refentrytitle>sd-id128</refentrytitle><manvolnum>3</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> + + <xi:include href="libsystemd-pkgconfig.xml" /> + + <refsect1> + <title>See Also</title> + + <para> + <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, + <citerefentry><refentrytitle>sd-id128</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry project='man-pages'><refentrytitle>printf</refentrytitle><manvolnum>3</manvolnum></citerefentry> + </para> + </refsect1> + +</refentry> |