56 lines
1.8 KiB
PHP
56 lines
1.8 KiB
PHP
<?php
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namespace Drupal\Component\Uuid;
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use Drupal\Component\Utility\Crypt;
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/**
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* Generates a UUID v4 (RFC 4122 section 4.4) using PHP code.
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*
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* @see http://www.rfc-editor.org/rfc/rfc4122.txt
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* @see http://www.rfc-editor.org/errata_search.php?rfc=4122&eid=3546
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*/
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class Php implements UuidInterface {
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/**
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* {@inheritdoc}
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*/
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public function generate() {
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// Obtain a random string of 32 hex characters.
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$hex = bin2hex(Crypt::randomBytes(16));
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// The variable names $time_low, $time_mid, $time_hi_and_version,
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// $clock_seq_hi_and_reserved, $clock_seq_low, and $node correlate to
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// the fields defined in RFC 4122 section 4.1.2.
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//
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// Use characters 0-11 to generate 32-bit $time_low and 16-bit $time_mid.
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$time_low = substr($hex, 0, 8);
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$time_mid = substr($hex, 8, 4);
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// Use characters 12-15 to generate 16-bit $time_hi_and_version.
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// The 4 most significant bits are the version number (0100 == 0x4).
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// We simply skip character 12 from $hex, and concatenate the strings.
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$time_hi_and_version = '4' . substr($hex, 13, 3);
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// Use characters 16-17 to generate 8-bit $clock_seq_hi_and_reserved.
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// The 2 most significant bits are set to one and zero respectively.
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$clock_seq_hi_and_reserved = base_convert(substr($hex, 16, 2), 16, 10);
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$clock_seq_hi_and_reserved &= 0b00111111;
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$clock_seq_hi_and_reserved |= 0b10000000;
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// Use characters 18-19 to generate 8-bit $clock_seq_low.
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$clock_seq_low = substr($hex, 18, 2);
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// Use characters 20-31 to generate 48-bit $node.
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$node = substr($hex, 20);
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// Re-combine as a UUID. $clock_seq_hi_and_reserved is still an integer.
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$uuid = sprintf('%s-%s-%s-%02x%s-%s',
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$time_low, $time_mid, $time_hi_and_version,
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$clock_seq_hi_and_reserved, $clock_seq_low,
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$node
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);
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return $uuid;
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}
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}
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