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// Package uuid provides implementation of Universally Unique Identifier (UUID).
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// Supported versions are 1, 3, 4 and 5 (as specified in RFC 4122) and
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// version 2 (as specified in DCE 1.1).
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package uid
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import (
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"bytes"
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"crypto/md5"
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"crypto/rand"
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"crypto/sha1"
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"database/sql/driver"
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"encoding/binary"
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"encoding/hex"
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"fmt"
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"hash"
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"net"
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"os"
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"sync"
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"time"
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)
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// UUID layout variants.
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const (
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VariantNCS = iota
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VariantRFC4122
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VariantMicrosoft
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VariantFuture
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)
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// UUID DCE domains.
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const (
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DomainPerson = iota
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DomainGroup
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DomainOrg
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)
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// Difference in 100-nanosecond intervals between
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// UUID epoch (October 15, 1582) and Unix epoch (January 1, 1970).
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const epochStart = 122192928000000000
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// Used in string method conversion
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const dash byte = '-'
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// UUID v1/v2 storage.
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var (
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storageMutex sync.Mutex
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storageOnce sync.Once
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epochFunc = unixTimeFunc
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clockSequence uint16
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lastTime uint64
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hardwareAddr [6]byte
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posixUID = uint32(os.Getuid())
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posixGID = uint32(os.Getgid())
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)
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// String parse helpers.
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var (
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urnPrefix = []byte("urn:uuid:")
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byteGroups = []int{8, 4, 4, 4, 12}
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)
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func initClockSequence() {
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buf := make([]byte, 2)
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safeRandom(buf)
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clockSequence = binary.BigEndian.Uint16(buf)
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}
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func initHardwareAddr() {
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interfaces, err := net.Interfaces()
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if err == nil {
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for _, iface := range interfaces {
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if len(iface.HardwareAddr) >= 6 {
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copy(hardwareAddr[:], iface.HardwareAddr)
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return
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}
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}
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}
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// Initialize hardwareAddr randomly in case
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// of real network interfaces absence
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safeRandom(hardwareAddr[:])
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// Set multicast bit as recommended in RFC 4122
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hardwareAddr[0] |= 0x01
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}
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func initStorage() {
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initClockSequence()
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initHardwareAddr()
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}
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func safeRandom(dest []byte) {
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if _, err := rand.Read(dest); err != nil {
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panic(err)
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}
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}
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// Returns difference in 100-nanosecond intervals between
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// UUID epoch (October 15, 1582) and current time.
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// This is default epoch calculation function.
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func unixTimeFunc() uint64 {
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return epochStart + uint64(time.Now().UnixNano()/100)
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}
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// UUID representation compliant with specification
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// described in RFC 4122.
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type UUID [16]byte
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// NullUUID can be used with the standard sql package to represent a
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// UUID value that can be NULL in the database
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type NullUUID struct {
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UUID UUID
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Valid bool
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}
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// The nil UUID is special form of UUID that is specified to have all
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// 128 bits set to zero.
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var Nil = UUID{}
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// Predefined namespace UUIDs.
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var (
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NamespaceDNS, _ = FromString("6ba7b810-9dad-11d1-80b4-00c04fd430c8")
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NamespaceURL, _ = FromString("6ba7b811-9dad-11d1-80b4-00c04fd430c8")
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NamespaceOID, _ = FromString("6ba7b812-9dad-11d1-80b4-00c04fd430c8")
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NamespaceX500, _ = FromString("6ba7b814-9dad-11d1-80b4-00c04fd430c8")
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)
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// And returns result of binary AND of two UUIDs.
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func And(u1 UUID, u2 UUID) UUID {
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u := UUID{}
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for i := 0; i < 16; i++ {
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u[i] = u1[i] & u2[i]
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}
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return u
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}
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// Or returns result of binary OR of two UUIDs.
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func Or(u1 UUID, u2 UUID) UUID {
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u := UUID{}
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for i := 0; i < 16; i++ {
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u[i] = u1[i] | u2[i]
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}
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return u
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}
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// Equal returns true if u1 and u2 equals, otherwise returns false.
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func Equal(u1 UUID, u2 UUID) bool {
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return bytes.Equal(u1[:], u2[:])
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}
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// Version returns algorithm version used to generate UUID.
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func (u UUID) Version() uint {
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return uint(u[6] >> 4)
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}
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// Variant returns UUID layout variant.
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func (u UUID) Variant() uint {
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switch {
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case (u[8] & 0x80) == 0x00:
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return VariantNCS
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case (u[8]&0xc0)|0x80 == 0x80:
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return VariantRFC4122
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case (u[8]&0xe0)|0xc0 == 0xc0:
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return VariantMicrosoft
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}
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return VariantFuture
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}
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// Bytes returns bytes slice representation of UUID.
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func (u UUID) Bytes() []byte {
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return u[:]
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}
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// Returns canonical string representation of UUID:
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// xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx.
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func (u UUID) String() string {
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buf := make([]byte, 36)
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hex.Encode(buf[0:8], u[0:4])
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buf[8] = dash
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hex.Encode(buf[9:13], u[4:6])
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buf[13] = dash
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hex.Encode(buf[14:18], u[6:8])
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buf[18] = dash
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hex.Encode(buf[19:23], u[8:10])
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buf[23] = dash
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hex.Encode(buf[24:], u[10:])
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return string(buf)
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}
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//0001 时间的版本
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//0010 DCE Security
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//0011 MD5哈希
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//0100 (伪)随机数
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//0101 SHA-1哈希
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// SetVersion sets version bits.
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func (u *UUID) SetVersion(v byte) {
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u[6] = (u[6] & 0x0f) | (v << 4)
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}
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// SetVariant sets variant bits as described in RFC 4122.
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func (u *UUID) SetVariant() {
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u[8] = (u[8] & 0xbf) | 0x80
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}
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// MarshalText implements the encoding.TextMarshaler interface.
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// The encoding is the same as returned by String.
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func (u UUID) MarshalText() (text []byte, err error) {
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text = []byte(u.String())
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return
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}
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// UnmarshalText implements the encoding.TextUnmarshaler interface.
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// Following formats are supported:
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// "6ba7b810-9dad-11d1-80b4-00c04fd430c8",
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// "{6ba7b810-9dad-11d1-80b4-00c04fd430c8}",
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// "urn:uuid:6ba7b810-9dad-11d1-80b4-00c04fd430c8"
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func (u *UUID) UnmarshalText(text []byte) (err error) {
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if len(text) < 32 {
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err = fmt.Errorf("uuid: UUID string too short: %s", text)
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return
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}
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t := text[:]
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braced := false
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if bytes.Equal(t[:9], urnPrefix) {
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t = t[9:]
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} else if t[0] == '{' {
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braced = true
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t = t[1:]
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}
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b := u[:]
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for i, byteGroup := range byteGroups {
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if i > 0 && t[0] == '-' {
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t = t[1:]
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} else if i > 0 && t[0] != '-' {
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err = fmt.Errorf("uuid: invalid string format")
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return
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}
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if i == 2 {
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if !bytes.Contains([]byte("012345"), []byte{t[0]}) {
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err = fmt.Errorf("uuid: invalid version number: %v", t[0])
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return
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}
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}
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if len(t) < byteGroup {
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err = fmt.Errorf("uuid: UUID string too short: %s", text)
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return
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}
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if i == 4 && len(t) > byteGroup &&
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((braced && t[byteGroup] != '}') || len(t[byteGroup:]) > 1 || !braced) {
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err = fmt.Errorf("uuid: UUID string too long: %s", t)
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return
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}
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_, err = hex.Decode(b[:byteGroup/2], t[:byteGroup])
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if err != nil {
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return
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}
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t = t[byteGroup:]
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b = b[byteGroup/2:]
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}
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return
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}
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// MarshalBinary implements the encoding.BinaryMarshaler interface.
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func (u UUID) MarshalBinary() (data []byte, err error) {
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data = u.Bytes()
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return
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}
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// UnmarshalBinary implements the encoding.BinaryUnmarshaler interface.
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// It will return error if the slice isn't 16 bytes long.
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func (u *UUID) UnmarshalBinary(data []byte) (err error) {
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if len(data) != 16 {
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err = fmt.Errorf("uuid: UUID must be exactly 16 bytes long, got %d bytes", len(data))
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return
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}
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copy(u[:], data)
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return
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}
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// Value implements the driver.Valuer interface.
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func (u UUID) Value() (driver.Value, error) {
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return u.String(), nil
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}
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// Scan implements the sql.Scanner interface.
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// A 16-byte slice is handled by UnmarshalBinary, while
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// a longer byte slice or a string is handled by UnmarshalText.
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func (u *UUID) Scan(src interface{}) error {
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switch src := src.(type) {
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case []byte:
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if len(src) == 16 {
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return u.UnmarshalBinary(src)
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}
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return u.UnmarshalText(src)
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case string:
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return u.UnmarshalText([]byte(src))
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}
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return fmt.Errorf("uuid: cannot convert %T to UUID", src)
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}
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// Value implements the driver.Valuer interface.
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func (u NullUUID) Value() (driver.Value, error) {
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if !u.Valid {
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return nil, nil
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}
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// Delegate to UUID Value function
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return u.UUID.Value()
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}
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// Scan implements the sql.Scanner interface.
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func (u *NullUUID) Scan(src interface{}) error {
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if src == nil {
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u.UUID, u.Valid = Nil, false
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return nil
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}
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// Delegate to UUID Scan function
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u.Valid = true
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return u.UUID.Scan(src)
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}
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// FromBytes returns UUID converted from raw byte slice input.
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// It will return error if the slice isn't 16 bytes long.
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func FromBytes(input []byte) (u UUID, err error) {
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err = u.UnmarshalBinary(input)
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return
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}
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// FromBytesOrNil returns UUID converted from raw byte slice input.
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// Same behavior as FromBytes, but returns a Nil UUID on error.
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func FromBytesOrNil(input []byte) UUID {
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uuid, err := FromBytes(input)
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if err != nil {
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return Nil
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}
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return uuid
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}
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// FromString returns UUID parsed from string input.
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// Input is expected in a form accepted by UnmarshalText.
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func FromString(input string) (u UUID, err error) {
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err = u.UnmarshalText([]byte(input))
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return
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}
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// FromStringOrNil returns UUID parsed from string input.
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// Same behavior as FromString, but returns a Nil UUID on error.
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func FromStringOrNil(input string) UUID {
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uuid, err := FromString(input)
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if err != nil {
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return Nil
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}
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return uuid
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}
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|
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// Returns UUID v1/v2 storage state.
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// Returns epoch timestamp, clock sequence, and hardware address.
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func getStorage() (uint64, uint16, []byte) {
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storageOnce.Do(initStorage)
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storageMutex.Lock()
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defer storageMutex.Unlock()
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timeNow := epochFunc()
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|
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// Clock changed backwards since last UUID generation.
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// Should increase clock sequence.
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if timeNow <= lastTime {
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clockSequence++
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}
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lastTime = timeNow
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return timeNow, clockSequence, hardwareAddr[:]
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}
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|
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// NewV1 returns UUID based on current timestamp and MAC address.
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|
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func NewV1() UUID {
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|
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u := UUID{}
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timeNow, clockSeq, hardwareAddr := getStorage()
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binary.BigEndian.PutUint32(u[0:], uint32(timeNow))
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|
|
binary.BigEndian.PutUint16(u[4:], uint16(timeNow>>32))
|
|
|
|
binary.BigEndian.PutUint16(u[6:], uint16(timeNow>>48))
|
|
|
|
binary.BigEndian.PutUint16(u[8:], clockSeq)
|
|
|
|
|
|
|
|
copy(u[10:], hardwareAddr)
|
|
|
|
|
|
|
|
u.SetVersion(1)
|
|
|
|
u.SetVariant()
|
|
|
|
|
|
|
|
return u
|
|
|
|
}
|
|
|
|
|
|
|
|
// NewV2 returns DCE Security UUID based on POSIX UID/GID.
|
|
|
|
func NewV2(domain byte) UUID {
|
|
|
|
u := UUID{}
|
|
|
|
|
|
|
|
timeNow, clockSeq, hardwareAddr := getStorage()
|
|
|
|
|
|
|
|
switch domain {
|
|
|
|
case DomainPerson:
|
|
|
|
binary.BigEndian.PutUint32(u[0:], posixUID)
|
|
|
|
case DomainGroup:
|
|
|
|
binary.BigEndian.PutUint32(u[0:], posixGID)
|
|
|
|
}
|
|
|
|
|
|
|
|
binary.BigEndian.PutUint16(u[4:], uint16(timeNow>>32))
|
|
|
|
binary.BigEndian.PutUint16(u[6:], uint16(timeNow>>48))
|
|
|
|
binary.BigEndian.PutUint16(u[8:], clockSeq)
|
|
|
|
u[9] = domain
|
|
|
|
|
|
|
|
copy(u[10:], hardwareAddr)
|
|
|
|
|
|
|
|
u.SetVersion(2)
|
|
|
|
u.SetVariant()
|
|
|
|
|
|
|
|
return u
|
|
|
|
}
|
|
|
|
|
|
|
|
// NewV3 returns UUID based on MD5 hash of namespace UUID and name.
|
|
|
|
func NewV3(ns UUID, name string) UUID {
|
|
|
|
u := newFromHash(md5.New(), ns, name)
|
|
|
|
u.SetVersion(3)
|
|
|
|
u.SetVariant()
|
|
|
|
|
|
|
|
return u
|
|
|
|
}
|
|
|
|
|
|
|
|
// NewV4 returns random generated UUID.
|
|
|
|
func NewV4() UUID {
|
|
|
|
u := UUID{}
|
|
|
|
safeRandom(u[:])
|
|
|
|
u.SetVersion(4)
|
|
|
|
u.SetVariant()
|
|
|
|
|
|
|
|
return u
|
|
|
|
}
|
|
|
|
|
|
|
|
// NewV5 returns UUID based on SHA-1 hash of namespace UUID and name.
|
|
|
|
func NewV5(ns UUID, name string) UUID {
|
|
|
|
u := newFromHash(sha1.New(), ns, name)
|
|
|
|
u.SetVersion(5)
|
|
|
|
u.SetVariant()
|
|
|
|
|
|
|
|
return u
|
|
|
|
}
|
|
|
|
|
|
|
|
// Returns UUID based on hashing of namespace UUID and name.
|
|
|
|
func newFromHash(h hash.Hash, ns UUID, name string) UUID {
|
|
|
|
u := UUID{}
|
|
|
|
h.Write(ns[:])
|
|
|
|
h.Write([]byte(name))
|
|
|
|
copy(u[:], h.Sum(nil))
|
|
|
|
|
|
|
|
return u
|
|
|
|
} |
...
|
...
|
|
