go1.16 (#14783)

vendor/github.com/Microsoft/go-winio/pkg/guid/guid.go

@@ -0,0 +1,235 @@
+// Package guid provides a GUID type. The backing structure for a GUID is
+// identical to that used by the golang.org/x/sys/windows GUID type.
+// There are two main binary encodings used for a GUID, the big-endian encoding,
+// and the Windows (mixed-endian) encoding. See here for details:
+// https://en.wikipedia.org/wiki/Universally_unique_identifier#Encoding
+package guid
+
+import (
+	"crypto/rand"
+	"crypto/sha1"
+	"encoding"
+	"encoding/binary"
+	"fmt"
+	"strconv"
+
+	"golang.org/x/sys/windows"
+)
+
+// Variant specifies which GUID variant (or "type") of the GUID. It determines
+// how the entirety of the rest of the GUID is interpreted.
+type Variant uint8
+
+// The variants specified by RFC 4122.
+const (
+	// VariantUnknown specifies a GUID variant which does not conform to one of
+	// the variant encodings specified in RFC 4122.
+	VariantUnknown Variant = iota
+	VariantNCS
+	VariantRFC4122
+	VariantMicrosoft
+	VariantFuture
+)
+
+// Version specifies how the bits in the GUID were generated. For instance, a
+// version 4 GUID is randomly generated, and a version 5 is generated from the
+// hash of an input string.
+type Version uint8
+
+var _ = (encoding.TextMarshaler)(GUID{})
+var _ = (encoding.TextUnmarshaler)(&GUID{})
+
+// GUID represents a GUID/UUID. It has the same structure as
+// golang.org/x/sys/windows.GUID so that it can be used with functions expecting
+// that type. It is defined as its own type so that stringification and
+// marshaling can be supported. The representation matches that used by native
+// Windows code.
+type GUID windows.GUID
+
+// NewV4 returns a new version 4 (pseudorandom) GUID, as defined by RFC 4122.
+func NewV4() (GUID, error) {
+	var b [16]byte
+	if _, err := rand.Read(b[:]); err != nil {
+		return GUID{}, err
+	}
+
+	g := FromArray(b)
+	g.setVersion(4) // Version 4 means randomly generated.
+	g.setVariant(VariantRFC4122)
+
+	return g, nil
+}
+
+// NewV5 returns a new version 5 (generated from a string via SHA-1 hashing)
+// GUID, as defined by RFC 4122. The RFC is unclear on the encoding of the name,
+// and the sample code treats it as a series of bytes, so we do the same here.
+//
+// Some implementations, such as those found on Windows, treat the name as a
+// big-endian UTF16 stream of bytes. If that is desired, the string can be
+// encoded as such before being passed to this function.
+func NewV5(namespace GUID, name []byte) (GUID, error) {
+	b := sha1.New()
+	namespaceBytes := namespace.ToArray()
+	b.Write(namespaceBytes[:])
+	b.Write(name)
+
+	a := [16]byte{}
+	copy(a[:], b.Sum(nil))
+
+	g := FromArray(a)
+	g.setVersion(5) // Version 5 means generated from a string.
+	g.setVariant(VariantRFC4122)
+
+	return g, nil
+}
+
+func fromArray(b [16]byte, order binary.ByteOrder) GUID {
+	var g GUID
+	g.Data1 = order.Uint32(b[0:4])
+	g.Data2 = order.Uint16(b[4:6])
+	g.Data3 = order.Uint16(b[6:8])
+	copy(g.Data4[:], b[8:16])
+	return g
+}
+
+func (g GUID) toArray(order binary.ByteOrder) [16]byte {
+	b := [16]byte{}
+	order.PutUint32(b[0:4], g.Data1)
+	order.PutUint16(b[4:6], g.Data2)
+	order.PutUint16(b[6:8], g.Data3)
+	copy(b[8:16], g.Data4[:])
+	return b
+}
+
+// FromArray constructs a GUID from a big-endian encoding array of 16 bytes.
+func FromArray(b [16]byte) GUID {
+	return fromArray(b, binary.BigEndian)
+}
+
+// ToArray returns an array of 16 bytes representing the GUID in big-endian
+// encoding.
+func (g GUID) ToArray() [16]byte {
+	return g.toArray(binary.BigEndian)
+}
+
+// FromWindowsArray constructs a GUID from a Windows encoding array of bytes.
+func FromWindowsArray(b [16]byte) GUID {
+	return fromArray(b, binary.LittleEndian)
+}
+
+// ToWindowsArray returns an array of 16 bytes representing the GUID in Windows
+// encoding.
+func (g GUID) ToWindowsArray() [16]byte {
+	return g.toArray(binary.LittleEndian)
+}
+
+func (g GUID) String() string {
+	return fmt.Sprintf(
+		"%08x-%04x-%04x-%04x-%012x",
+		g.Data1,
+		g.Data2,
+		g.Data3,
+		g.Data4[:2],
+		g.Data4[2:])
+}
+
+// FromString parses a string containing a GUID and returns the GUID. The only
+// format currently supported is the `xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx`
+// format.
+func FromString(s string) (GUID, error) {
+	if len(s) != 36 {
+		return GUID{}, fmt.Errorf("invalid GUID %q", s)
+	}
+	if s[8] != '-' || s[13] != '-' || s[18] != '-' || s[23] != '-' {
+		return GUID{}, fmt.Errorf("invalid GUID %q", s)
+	}
+
+	var g GUID
+
+	data1, err := strconv.ParseUint(s[0:8], 16, 32)
+	if err != nil {
+		return GUID{}, fmt.Errorf("invalid GUID %q", s)
+	}
+	g.Data1 = uint32(data1)
+
+	data2, err := strconv.ParseUint(s[9:13], 16, 16)
+	if err != nil {
+		return GUID{}, fmt.Errorf("invalid GUID %q", s)
+	}
+	g.Data2 = uint16(data2)
+
+	data3, err := strconv.ParseUint(s[14:18], 16, 16)
+	if err != nil {
+		return GUID{}, fmt.Errorf("invalid GUID %q", s)
+	}
+	g.Data3 = uint16(data3)
+
+	for i, x := range []int{19, 21, 24, 26, 28, 30, 32, 34} {
+		v, err := strconv.ParseUint(s[x:x+2], 16, 8)
+		if err != nil {
+			return GUID{}, fmt.Errorf("invalid GUID %q", s)
+		}
+		g.Data4[i] = uint8(v)
+	}
+
+	return g, nil
+}
+
+func (g *GUID) setVariant(v Variant) {
+	d := g.Data4[0]
+	switch v {
+	case VariantNCS:
+		d = (d & 0x7f)
+	case VariantRFC4122:
+		d = (d & 0x3f) | 0x80
+	case VariantMicrosoft:
+		d = (d & 0x1f) | 0xc0
+	case VariantFuture:
+		d = (d & 0x0f) | 0xe0
+	case VariantUnknown:
+		fallthrough
+	default:
+		panic(fmt.Sprintf("invalid variant: %d", v))
+	}
+	g.Data4[0] = d
+}
+
+// Variant returns the GUID variant, as defined in RFC 4122.
+func (g GUID) Variant() Variant {
+	b := g.Data4[0]
+	if b&0x80 == 0 {
+		return VariantNCS
+	} else if b&0xc0 == 0x80 {
+		return VariantRFC4122
+	} else if b&0xe0 == 0xc0 {
+		return VariantMicrosoft
+	} else if b&0xe0 == 0xe0 {
+		return VariantFuture
+	}
+	return VariantUnknown
+}
+
+func (g *GUID) setVersion(v Version) {
+	g.Data3 = (g.Data3 & 0x0fff) | (uint16(v) << 12)
+}
+
+// Version returns the GUID version, as defined in RFC 4122.
+func (g GUID) Version() Version {
+	return Version((g.Data3 & 0xF000) >> 12)
+}
+
+// MarshalText returns the textual representation of the GUID.
+func (g GUID) MarshalText() ([]byte, error) {
+	return []byte(g.String()), nil
+}
+
+// UnmarshalText takes the textual representation of a GUID, and unmarhals it
+// into this GUID.
+func (g *GUID) UnmarshalText(text []byte) error {
+	g2, err := FromString(string(text))
+	if err != nil {
+		return err
+	}
+	*g = g2
+	return nil
+}