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sd-id128: add compound literal love to sd_id128_to_string() + id128_to_uuid_string()
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@ -633,7 +633,10 @@ manpages = [
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'sd_id128_get_machine_app_specific'],
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''],
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['sd_id128_randomize', '3', [], ''],
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['sd_id128_to_string', '3', ['sd_id128_from_string'], ''],
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['sd_id128_to_string',
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'3',
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['SD_ID128_STRING_MAX', 'SD_ID128_TO_STRING', 'sd_id128_from_string'],
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''],
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['sd_is_fifo',
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'3',
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['sd_is_mq',
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@ -17,7 +17,9 @@
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<refnamediv>
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<refname>sd_id128_to_string</refname>
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<refname>SD_ID128_TO_STRING</refname>
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<refname>sd_id128_from_string</refname>
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<refname>SD_ID128_STRING_MAX</refname>
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<refpurpose>Format or parse 128-bit IDs as strings</refpurpose>
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</refnamediv>
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@ -25,9 +27,13 @@
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<funcsynopsis>
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<funcsynopsisinfo>#include <systemd/sd-id128.h></funcsynopsisinfo>
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<funcsynopsisinfo>#define SD_ID128_STRING_MAX 33U</funcsynopsisinfo>
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<funcsynopsisinfo>#define SD_ID128_TO_STRING(id) …</funcsynopsisinfo>
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<funcprototype>
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<funcdef>char *<function>sd_id128_to_string</function></funcdef>
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<paramdef>sd_id128_t <parameter>id</parameter>, char <parameter>s</parameter>[33]</paramdef>
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<paramdef>sd_id128_t <parameter>id</parameter>, char <parameter>s</parameter>[static SD_ID128_STRING_MAX]</paramdef>
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</funcprototype>
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<funcprototype>
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@ -41,47 +47,48 @@
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<refsect1>
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<title>Description</title>
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<para><function>sd_id128_to_string()</function> formats a 128-bit
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ID as a character string. It expects the ID and a string array
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capable of storing 33 characters. The ID will be formatted as 32
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lowercase hexadecimal digits and be terminated by a
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<constant>NUL</constant> byte.</para>
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<para><function>sd_id128_to_string()</function> formats a 128-bit ID as a character string. It expects
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the ID and a string array capable of storing 33 characters
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(<constant>SD_ID128_STRING_MAX</constant>). The ID will be formatted as 32 lowercase hexadecimal digits
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and be terminated by a <constant>NUL</constant> byte.</para>
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<para><function>sd_id128_from_string()</function> implements the reverse operation: it takes a 33 character string
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with 32 hexadecimal digits (either lowercase or uppercase, terminated by <constant>NUL</constant>) and parses them
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back into a 128-bit ID returned in <parameter>ret</parameter>. Alternatively, this call can also parse a
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37-character string with a 128-bit ID formatted as RFC UUID. If <parameter>ret</parameter> is passed as
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<constant>NULL</constant> the function will validate the passed ID string, but not actually return it in parsed
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form.</para>
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<para><function>SD_ID128_TO_STRING()</function> is a macro that wraps
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<function>sd_id128_to_string()</function> and passes an appropriately sized buffer as second argument,
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allocated as C99 compound literal. Each use will thus implicitly acquire a suitable buffer on the stack
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which remains valid until the end of the current code block. This is usually the simplest way to acquire
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a string representation of a 128-bit ID in a buffer that is valid in the current code block.</para>
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<para><function>sd_id128_from_string()</function> implements the reverse operation: it takes a 33
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character string with 32 hexadecimal digits (either lowercase or uppercase, terminated by
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<constant>NUL</constant>) and parses them back into a 128-bit ID returned in
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<parameter>ret</parameter>. Alternatively, this call can also parse a 37-character string with a 128-bit
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ID formatted as RFC UUID. If <parameter>ret</parameter> is passed as <constant>NULL</constant> the
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function will validate the passed ID string, but not actually return it in parsed form.</para>
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<para>Note that when parsing 37 character UUIDs this is done strictly in Big Endian byte order,
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i.e. according to <ulink url="https://tools.ietf.org/html/rfc4122">RFC4122</ulink> Variant 1
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rules, even if the UUID encodes a different variant. This matches behaviour in various other Linux
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userspace tools. It's probably wise to avoid UUIDs of other variant types.</para>
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i.e. according to <ulink url="https://tools.ietf.org/html/rfc4122">RFC4122</ulink> Variant 1 rules, even
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if the UUID encodes a different variant. This matches behaviour in various other Linux userspace
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tools. It's probably wise to avoid UUIDs of other variant types.</para>
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<para>For more information about the <literal>sd_id128_t</literal>
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type see
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<citerefentry><refentrytitle>sd-id128</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
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Note that these calls operate the same way on all architectures,
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i.e. the results do not depend on endianness.</para>
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<para>For more information about the <literal>sd_id128_t</literal> type see
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<citerefentry><refentrytitle>sd-id128</refentrytitle><manvolnum>3</manvolnum></citerefentry>. Note that
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these calls operate the same way on all architectures, i.e. the results do not depend on
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endianness.</para>
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<para>When formatting a 128-bit ID into a string, it is often
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easier to use a format string for
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<citerefentry project='man-pages'><refentrytitle>printf</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
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This is easily done using the
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<constant>SD_ID128_FORMAT_STR</constant> and <function>SD_ID128_FORMAT_VAL()</function> macros. For
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more information see
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<para>When formatting a 128-bit ID into a string, it is often easier to use a format string for
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<citerefentry
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project='man-pages'><refentrytitle>printf</refentrytitle><manvolnum>3</manvolnum></citerefentry>. This
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is easily done using the <constant>SD_ID128_FORMAT_STR</constant> and
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<function>SD_ID128_FORMAT_VAL()</function> macros. For more information see
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<citerefentry><refentrytitle>sd-id128</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
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</refsect1>
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<refsect1>
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<title>Return Value</title>
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<para><function>sd_id128_to_string()</function> always succeeds
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and returns a pointer to the string array passed in.
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<function>sd_id128_from_string()</function> returns 0 on success, in
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which case <parameter>ret</parameter> is filled in, or a negative
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errno-style error code.</para>
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<para><function>sd_id128_to_string()</function> always succeeds and returns a pointer to the string array
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passed in. <function>sd_id128_from_string()</function> returns 0 on success, in which case
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<parameter>ret</parameter> is filled in, or a negative errno-style error code.</para>
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</refsect1>
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<xi:include href="libsystemd-pkgconfig.xml" />
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@ -12,6 +12,8 @@
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char *id128_to_uuid_string(sd_id128_t id, char s[static ID128_UUID_STRING_MAX]);
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#define ID128_TO_UUID_STRING(id) id128_to_uuid_string((id), (char[ID128_UUID_STRING_MAX]) {})
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bool id128_is_valid(const char *s) _pure_;
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typedef enum Id128Format {
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@ -34,11 +34,13 @@ union sd_id128 {
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uint64_t qwords[2];
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};
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#define SD_ID128_STRING_MAX 33
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#define SD_ID128_STRING_MAX 33U
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char *sd_id128_to_string(sd_id128_t id, char s[_SD_ARRAY_STATIC SD_ID128_STRING_MAX]);
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int sd_id128_from_string(const char *s, sd_id128_t *ret);
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#define SD_ID128_TO_STRING(id) sd_id128_to_string((id), (char[SD_ID128_STRING_MAX]) {})
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int sd_id128_randomize(sd_id128_t *ret);
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int sd_id128_get_machine(sd_id128_t *ret);
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