github.com/mdaxf/iac@v0.0.0-20240519030858-58a061660378/vendor_skip/go.mongodb.org/mongo-driver/internal/uuid/uuid.go (about)

     1  // Copyright (C) MongoDB, Inc. 2017-present.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License"); you may
     4  // not use this file except in compliance with the License. You may obtain
     5  // a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
     6  
     7  package uuid
     8  
     9  import (
    10  	"encoding/hex"
    11  	"io"
    12  
    13  	"go.mongodb.org/mongo-driver/internal/randutil"
    14  )
    15  
    16  // UUID represents a UUID.
    17  type UUID [16]byte
    18  
    19  // A source is a UUID generator that reads random values from a io.Reader.
    20  // It should be safe to use from multiple goroutines.
    21  type source struct {
    22  	random io.Reader
    23  }
    24  
    25  // new returns a random UUIDv4 with bytes read from the source's random number generator.
    26  func (s *source) new() (UUID, error) {
    27  	var uuid UUID
    28  	_, err := io.ReadFull(s.random, uuid[:])
    29  	if err != nil {
    30  		return UUID{}, err
    31  	}
    32  	uuid[6] = (uuid[6] & 0x0f) | 0x40 // Version 4
    33  	uuid[8] = (uuid[8] & 0x3f) | 0x80 // Variant is 10
    34  	return uuid, nil
    35  }
    36  
    37  // newSource returns a source that uses a pseudo-random number generator in reandutil package.
    38  // It is intended to be used to initialize the package-global UUID generator.
    39  func newSource() *source {
    40  	return &source{
    41  		random: randutil.NewLockedRand(),
    42  	}
    43  }
    44  
    45  // globalSource is a package-global pseudo-random UUID generator.
    46  var globalSource = newSource()
    47  
    48  // New returns a random UUIDv4. It uses a global pseudo-random number generator in randutil
    49  // at package initialization.
    50  //
    51  // New should not be used to generate cryptographically-secure random UUIDs.
    52  func New() (UUID, error) {
    53  	return globalSource.new()
    54  }
    55  
    56  func (uuid UUID) String() string {
    57  	var str [36]byte
    58  	hex.Encode(str[:], uuid[:4])
    59  	str[8] = '-'
    60  	hex.Encode(str[9:13], uuid[4:6])
    61  	str[13] = '-'
    62  	hex.Encode(str[14:18], uuid[6:8])
    63  	str[18] = '-'
    64  	hex.Encode(str[19:23], uuid[8:10])
    65  	str[23] = '-'
    66  	hex.Encode(str[24:], uuid[10:])
    67  	return string(str[:])
    68  }