69 lines
1.8 KiB
Go
69 lines
1.8 KiB
Go
// Copyright (C) MongoDB, Inc. 2017-present.
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//
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// Licensed under the Apache License, Version 2.0 (the "License"); you may
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// not use this file except in compliance with the License. You may obtain
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// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
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package uuid
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import (
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"encoding/hex"
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"io"
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"go.mongodb.org/mongo-driver/internal/randutil"
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)
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// UUID represents a UUID.
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type UUID [16]byte
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// A source is a UUID generator that reads random values from a io.Reader.
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// It should be safe to use from multiple goroutines.
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type source struct {
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random io.Reader
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}
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// new returns a random UUIDv4 with bytes read from the source's random number generator.
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func (s *source) new() (UUID, error) {
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var uuid UUID
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_, err := io.ReadFull(s.random, uuid[:])
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if err != nil {
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return UUID{}, err
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}
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uuid[6] = (uuid[6] & 0x0f) | 0x40 // Version 4
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uuid[8] = (uuid[8] & 0x3f) | 0x80 // Variant is 10
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return uuid, nil
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}
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// newSource returns a source that uses a pseudo-random number generator in reandutil package.
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// It is intended to be used to initialize the package-global UUID generator.
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func newSource() *source {
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return &source{
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random: randutil.NewLockedRand(),
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}
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}
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// globalSource is a package-global pseudo-random UUID generator.
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var globalSource = newSource()
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// New returns a random UUIDv4. It uses a global pseudo-random number generator in randutil
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// at package initialization.
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//
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// New should not be used to generate cryptographically-secure random UUIDs.
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func New() (UUID, error) {
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return globalSource.new()
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}
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func (uuid UUID) String() string {
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var str [36]byte
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hex.Encode(str[:], uuid[:4])
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str[8] = '-'
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hex.Encode(str[9:13], uuid[4:6])
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str[13] = '-'
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hex.Encode(str[14:18], uuid[6:8])
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str[18] = '-'
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hex.Encode(str[19:23], uuid[8:10])
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str[23] = '-'
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hex.Encode(str[24:], uuid[10:])
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return string(str[:])
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}
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