windows/registry: add new package to manipulate Windows registry

Change-Id: Ia7c3d6250c041b95aa43ca5ca2a92251c480ef77
Reviewed-on: https://go-review.googlesource.com/8843
Reviewed-by: Rob Pike <r@golang.org>

windows/registry/key.go

@@ -0,0 +1,178 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build windows
+
+// Package registry provides access to the Windows registry.
+//
+// Here is a simple example, opening a registry key and reading a string value from it.
+//
+//	k, err := registry.OpenKey(registry.LOCAL_MACHINE, `SOFTWARE\Microsoft\Windows NT\CurrentVersion`, registry.QUERY_VALUE)
+//	if err != nil {
+//		log.Fatal(err)
+//	}
+//	defer k.Close()
+//
+//	s, _, err := k.GetStringValue("SystemRoot")
+//	if err != nil {
+//		log.Fatal(err)
+//	}
+//	fmt.Printf("Windows system root is %q\n", s)
+//
+package registry
+
+import (
+	"io"
+	"syscall"
+	"time"
+)
+
+const (
+	// Registry key security and access rights.
+	// See https://msdn.microsoft.com/en-us/library/windows/desktop/ms724878.aspx
+	// for details.
+	ALL_ACCESS         = 0xf003f
+	CREATE_LINK        = 0x00020
+	CREATE_SUB_KEY     = 0x00004
+	ENUMERATE_SUB_KEYS = 0x00008
+	EXECUTE            = 0x20019
+	NOTIFY             = 0x00010
+	QUERY_VALUE        = 0x00001
+	READ               = 0x20019
+	SET_VALUE          = 0x00002
+	WOW64_32KEY        = 0x00200
+	WOW64_64KEY        = 0x00100
+	WRITE              = 0x20006
+)
+
+// Key is a handle to an open Windows registry key.
+// Keys can be obtained by calling OpenKey; there are
+// also some predefined root keys such as CURRENT_USER.
+// Keys can be used directly in the Windows API.
+type Key syscall.Handle
+
+const (
+	// Windows defines some predefined root keys that are always open.
+	// An application can use these keys as entry points to the registry.
+	// Normally these keys are used in OpenKey to open new keys,
+	// but they can also be used anywhere a Key is required.
+	CLASSES_ROOT   = Key(syscall.HKEY_CLASSES_ROOT)
+	CURRENT_USER   = Key(syscall.HKEY_CURRENT_USER)
+	LOCAL_MACHINE  = Key(syscall.HKEY_LOCAL_MACHINE)
+	USERS          = Key(syscall.HKEY_USERS)
+	CURRENT_CONFIG = Key(syscall.HKEY_CURRENT_CONFIG)
+)
+
+// Close closes open key k.
+func (k Key) Close() error {
+	return syscall.RegCloseKey(syscall.Handle(k))
+}
+
+// OpenKey opens a new key with path name relative to key k.
+// It accepts any open key, including CURRENT_USER and others,
+// and returns the new key and an error.
+// The access parameter specifies desired access rights to the
+// key to be opened.
+func OpenKey(k Key, path string, access uint32) (Key, error) {
+	p, err := syscall.UTF16PtrFromString(path)
+	if err != nil {
+		return 0, err
+	}
+	var subkey syscall.Handle
+	err = syscall.RegOpenKeyEx(syscall.Handle(k), p, 0, access, &subkey)
+	if err != nil {
+		return 0, err
+	}
+	return Key(subkey), nil
+}
+
+// ReadSubKeyNames returns the names of subkeys of key k.
+// The parameter n controls the number of returned names,
+// analogous to the way os.File.Readdirnames works.
+func (k Key) ReadSubKeyNames(n int) ([]string, error) {
+	ki, err := k.Stat()
+	if err != nil {
+		return nil, err
+	}
+	names := make([]string, 0, ki.SubKeyCount)
+	buf := make([]uint16, ki.MaxSubKeyLen+1) // extra room for terminating zero byte
+loopItems:
+	for i := uint32(0); ; i++ {
+		if n > 0 {
+			if len(names) == n {
+				return names, nil
+			}
+		}
+		l := uint32(len(buf))
+		for {
+			err := syscall.RegEnumKeyEx(syscall.Handle(k), i, &buf[0], &l, nil, nil, nil, nil)
+			if err == nil {
+				break
+			}
+			if err == syscall.ERROR_MORE_DATA {
+				// Double buffer size and try again.
+				l = uint32(2 * len(buf))
+				buf = make([]uint16, l)
+				continue
+			}
+			if err == _ERROR_NO_MORE_ITEMS {
+				break loopItems
+			}
+			return names, err
+		}
+		names = append(names, syscall.UTF16ToString(buf[:l]))
+	}
+	if n > len(names) {
+		return names, io.EOF
+	}
+	return names, nil
+}
+
+// CreateKey creates a key named path under open key k.
+// CreateKey returns the new key and a boolean flag that reports
+// whether the key already existed.
+// The access parameter specifies the access rights for the key
+// to be created.
+func CreateKey(k Key, path string, access uint32) (newk Key, openedExisting bool, err error) {
+	var h syscall.Handle
+	var d uint32
+	err = regCreateKeyEx(syscall.Handle(k), syscall.StringToUTF16Ptr(path),
+		0, nil, _REG_OPTION_NON_VOLATILE, access, nil, &h, &d)
+	if err != nil {
+		return 0, false, err
+	}
+	return Key(h), d == _REG_OPENED_EXISTING_KEY, nil
+}
+
+// DeleteKey deletes the subkey path of key k and its values.
+func DeleteKey(k Key, path string) error {
+	return regDeleteKey(syscall.Handle(k), syscall.StringToUTF16Ptr(path))
+}
+
+// A KeyInfo describes the statistics of a key. It is returned by Stat.
+type KeyInfo struct {
+	SubKeyCount     uint32
+	MaxSubKeyLen    uint32 // size of the key's subkey with the longest name, in Unicode characters, not including the terminating zero byte
+	ValueCount      uint32
+	MaxValueNameLen uint32 // size of the key's longest value name, in Unicode characters, not including the terminating zero byte
+	MaxValueLen     uint32 // longest data component among the key's values, in bytes
+	lastWriteTime   syscall.Filetime
+}
+
+// ModTime returns the key's last write time.
+func (ki *KeyInfo) ModTime() time.Time {
+	return time.Unix(0, ki.lastWriteTime.Nanoseconds())
+}
+
+// Stat retrieves information about the open key k.
+func (k Key) Stat() (*KeyInfo, error) {
+	var ki KeyInfo
+	err := syscall.RegQueryInfoKey(syscall.Handle(k), nil, nil, nil,
+		&ki.SubKeyCount, &ki.MaxSubKeyLen, nil, &ki.ValueCount,
+		&ki.MaxValueNameLen, &ki.MaxValueLen, nil, &ki.lastWriteTime)
+	if err != nil {
+		return nil, err
+	}
+	return &ki, nil
+}

windows/registry/registry_test.go

@@ -0,0 +1,617 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build windows
+
+package registry_test
+
+import (
+	"bytes"
+	"crypto/rand"
+	"os"
+	"syscall"
+	"testing"
+	"time"
+
+	"golang.org/x/sys/windows/registry"
+)
+
+func randKeyName(prefix string) string {
+	const numbers = "0123456789"
+	buf := make([]byte, 10)
+	rand.Read(buf)
+	for i, b := range buf {
+		buf[i] = numbers[b%byte(len(numbers))]
+	}
+	return prefix + string(buf)
+}
+
+func TestReadSubKeyNames(t *testing.T) {
+	k, err := registry.OpenKey(registry.CLASSES_ROOT, "TypeLib", registry.ENUMERATE_SUB_KEYS|registry.QUERY_VALUE)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer k.Close()
+
+	names, err := k.ReadSubKeyNames(-1)
+	if err != nil {
+		t.Fatal(err)
+	}
+	var foundStdOle bool
+	for _, name := range names {
+		// Every PC has "stdole 2.0 OLE Automation" library installed.
+		if name == "{00020430-0000-0000-C000-000000000046}" {
+			foundStdOle = true
+		}
+	}
+	if !foundStdOle {
+		t.Fatal("could not find stdole 2.0 OLE Automation")
+	}
+}
+
+func TestCreateOpenDeleteKey(t *testing.T) {
+	k, err := registry.OpenKey(registry.CURRENT_USER, "Software", registry.QUERY_VALUE)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer k.Close()
+
+	testKName := randKeyName("TestCreateOpenDeleteKey_")
+
+	testK, exist, err := registry.CreateKey(k, testKName, registry.CREATE_SUB_KEY)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer testK.Close()
+
+	if exist {
+		t.Fatalf("key %q already exists", testKName)
+	}
+
+	testKAgain, exist, err := registry.CreateKey(k, testKName, registry.CREATE_SUB_KEY)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer testKAgain.Close()
+
+	if !exist {
+		t.Fatalf("key %q should already exist", testKName)
+	}
+
+	testKOpened, err := registry.OpenKey(k, testKName, registry.ENUMERATE_SUB_KEYS)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer testKOpened.Close()
+
+	err = registry.DeleteKey(k, testKName)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	testKOpenedAgain, err := registry.OpenKey(k, testKName, registry.ENUMERATE_SUB_KEYS)
+	if err == nil {
+		defer testKOpenedAgain.Close()
+		t.Fatalf("key %q should already been deleted", testKName)
+	}
+	if err != registry.ErrNotExist {
+		t.Fatalf(`unexpected error ("not exist" expected): %v`, err)
+	}
+}
+
+func equalStringSlice(a, b []string) bool {
+	if len(a) != len(b) {
+		return false
+	}
+	if a == nil {
+		return true
+	}
+	for i := range a {
+		if a[i] != b[i] {
+			return false
+		}
+	}
+	return true
+}
+
+type ValueTest struct {
+	Type     uint32
+	Name     string
+	Value    interface{}
+	WillFail bool
+}
+
+var ValueTests = []ValueTest{
+	{Type: registry.SZ, Name: "String1", Value: ""},
+	{Type: registry.SZ, Name: "String2", Value: "\000", WillFail: true},
+	{Type: registry.SZ, Name: "String3", Value: "Hello World"},
+	{Type: registry.SZ, Name: "String4", Value: "Hello World\000", WillFail: true},
+	{Type: registry.EXPAND_SZ, Name: "ExpString1", Value: ""},
+	{Type: registry.EXPAND_SZ, Name: "ExpString2", Value: "\000", WillFail: true},
+	{Type: registry.EXPAND_SZ, Name: "ExpString3", Value: "Hello World"},
+	{Type: registry.EXPAND_SZ, Name: "ExpString4", Value: "Hello\000World", WillFail: true},
+	{Type: registry.EXPAND_SZ, Name: "ExpString5", Value: "%PATH%"},
+	{Type: registry.EXPAND_SZ, Name: "ExpString6", Value: "%NO_SUCH_VARIABLE%"},
+	{Type: registry.EXPAND_SZ, Name: "ExpString7", Value: "%PATH%;."},
+	{Type: registry.BINARY, Name: "Binary1", Value: []byte{}},
+	{Type: registry.BINARY, Name: "Binary2", Value: []byte{1, 2, 3}},
+	{Type: registry.BINARY, Name: "Binary3", Value: []byte{3, 2, 1, 0, 1, 2, 3}},
+	{Type: registry.DWORD, Name: "Dword1", Value: uint64(0)},
+	{Type: registry.DWORD, Name: "Dword2", Value: uint64(1)},
+	{Type: registry.DWORD, Name: "Dword3", Value: uint64(0xff)},
+	{Type: registry.DWORD, Name: "Dword4", Value: uint64(0xffff)},
+	{Type: registry.QWORD, Name: "Qword1", Value: uint64(0)},
+	{Type: registry.QWORD, Name: "Qword2", Value: uint64(1)},
+	{Type: registry.QWORD, Name: "Qword3", Value: uint64(0xff)},
+	{Type: registry.QWORD, Name: "Qword4", Value: uint64(0xffff)},
+	{Type: registry.QWORD, Name: "Qword5", Value: uint64(0xffffff)},
+	{Type: registry.QWORD, Name: "Qword6", Value: uint64(0xffffffff)},
+	{Type: registry.MULTI_SZ, Name: "MultiString1", Value: []string{"a", "b", "c"}},
+	{Type: registry.MULTI_SZ, Name: "MultiString2", Value: []string{"abc", "", "cba"}},
+	{Type: registry.MULTI_SZ, Name: "MultiString3", Value: []string{""}},
+	{Type: registry.MULTI_SZ, Name: "MultiString4", Value: []string{"abcdef"}},
+	{Type: registry.MULTI_SZ, Name: "MultiString5", Value: []string{"\000"}, WillFail: true},
+	{Type: registry.MULTI_SZ, Name: "MultiString6", Value: []string{"a\000b"}, WillFail: true},
+	{Type: registry.MULTI_SZ, Name: "MultiString7", Value: []string{"ab", "\000", "cd"}, WillFail: true},
+	{Type: registry.MULTI_SZ, Name: "MultiString8", Value: []string{"\000", "cd"}, WillFail: true},
+	{Type: registry.MULTI_SZ, Name: "MultiString9", Value: []string{"ab", "\000"}, WillFail: true},
+}
+
+func setValues(t *testing.T, k registry.Key) {
+	for _, test := range ValueTests {
+		var err error
+		switch test.Type {
+		case registry.SZ:
+			err = k.SetStringValue(test.Name, test.Value.(string))
+		case registry.EXPAND_SZ:
+			err = k.SetExpandStringValue(test.Name, test.Value.(string))
+		case registry.MULTI_SZ:
+			err = k.SetStringsValue(test.Name, test.Value.([]string))
+		case registry.BINARY:
+			err = k.SetBinaryValue(test.Name, test.Value.([]byte))
+		case registry.DWORD:
+			err = k.SetDWordValue(test.Name, uint32(test.Value.(uint64)))
+		case registry.QWORD:
+			err = k.SetQWordValue(test.Name, test.Value.(uint64))
+		default:
+			t.Fatalf("unsupported type %d for %s value", test.Type, test.Name)
+		}
+		if test.WillFail {
+			if err == nil {
+				t.Fatalf("setting %s value %q should fail, but succeeded", test.Name, test.Value)
+			}
+		} else {
+			if err != nil {
+				t.Fatal(err)
+			}
+		}
+	}
+}
+
+func enumerateValues(t *testing.T, k registry.Key) {
+	names, err := k.ReadValueNames(-1)
+	if err != nil {
+		t.Error(err)
+		return
+	}
+	haveNames := make(map[string]bool)
+	for _, n := range names {
+		haveNames[n] = false
+	}
+	for _, test := range ValueTests {
+		wantFound := !test.WillFail
+		_, haveFound := haveNames[test.Name]
+		if wantFound && !haveFound {
+			t.Errorf("value %s is not found while enumerating", test.Name)
+		}
+		if haveFound && !wantFound {
+			t.Errorf("value %s is found while enumerating, but expected to fail", test.Name)
+		}
+		if haveFound {
+			delete(haveNames, test.Name)
+		}
+	}
+	for n, v := range haveNames {
+		t.Errorf("value %s (%v) is found while enumerating, but has not been cretaed", n, v)
+	}
+}
+
+func testErrNotExist(t *testing.T, name string, err error) {
+	if err == nil {
+		t.Errorf("%s value should not exist", name)
+		return
+	}
+	if err != registry.ErrNotExist {
+		t.Errorf("reading %s value should return 'not exist' error, but got: %s", name, err)
+		return
+	}
+}
+
+func testErrUnexpectedType(t *testing.T, test ValueTest, gottype uint32, err error) {
+	if err == nil {
+		t.Errorf("GetXValue(%q) should not succeed", test.Name)
+		return
+	}
+	if err != registry.ErrUnexpectedType {
+		t.Errorf("reading %s value should return 'unexpected key value type' error, but got: %s", test.Name, err)
+		return
+	}
+	if gottype != test.Type {
+		t.Errorf("want %s value type %v, got %v", test.Name, test.Type, gottype)
+		return
+	}
+}
+
+func testGetStringValue(t *testing.T, k registry.Key, test ValueTest) {
+	got, gottype, err := k.GetStringValue(test.Name)
+	if err != nil {
+		t.Errorf("GetStringValue(%s) failed: %v", test.Name, err)
+		return
+	}
+	if got != test.Value {
+		t.Errorf("want %s value %q, got %q", test.Name, test.Value, got)
+		return
+	}
+	if gottype != test.Type {
+		t.Errorf("want %s value type %v, got %v", test.Name, test.Type, gottype)
+		return
+	}
+	if gottype == registry.EXPAND_SZ {
+		_, err = registry.ExpandString(got)
+		if err != nil {
+			t.Errorf("ExpandString(%s) failed: %v", got, err)
+			return
+		}
+	}
+}
+
+func testGetIntegerValue(t *testing.T, k registry.Key, test ValueTest) {
+	got, gottype, err := k.GetIntegerValue(test.Name)
+	if err != nil {
+		t.Errorf("GetIntegerValue(%s) failed: %v", test.Name, err)
+		return
+	}
+	if got != test.Value.(uint64) {
+		t.Errorf("want %s value %v, got %v", test.Name, test.Value, got)
+		return
+	}
+	if gottype != test.Type {
+		t.Errorf("want %s value type %v, got %v", test.Name, test.Type, gottype)
+		return
+	}
+}
+
+func testGetBinaryValue(t *testing.T, k registry.Key, test ValueTest) {
+	got, gottype, err := k.GetBinaryValue(test.Name)
+	if err != nil {
+		t.Errorf("GetBinaryValue(%s) failed: %v", test.Name, err)
+		return
+	}
+	if !bytes.Equal(got, test.Value.([]byte)) {
+		t.Errorf("want %s value %v, got %v", test.Name, test.Value, got)
+		return
+	}
+	if gottype != test.Type {
+		t.Errorf("want %s value type %v, got %v", test.Name, test.Type, gottype)
+		return
+	}
+}
+
+func testGetStringsValue(t *testing.T, k registry.Key, test ValueTest) {
+	got, gottype, err := k.GetStringsValue(test.Name)
+	if err != nil {
+		t.Errorf("GetStringsValue(%s) failed: %v", test.Name, err)
+		return
+	}
+	if !equalStringSlice(got, test.Value.([]string)) {
+		t.Errorf("want %s value %#v, got %#v", test.Name, test.Value, got)
+		return
+	}
+	if gottype != test.Type {
+		t.Errorf("want %s value type %v, got %v", test.Name, test.Type, gottype)
+		return
+	}
+}
+
+func testGetValue(t *testing.T, k registry.Key, test ValueTest, size int) {
+	if size <= 0 {
+		return
+	}
+	// read data with no buffer
+	gotsize, gottype, err := k.GetValue(test.Name, nil)
+	if err != nil {
+		t.Errorf("GetValue(%s, [%d]byte) failed: %v", test.Name, size, err)
+		return
+	}
+	if gotsize != size {
+		t.Errorf("want %s value size of %d, got %v", test.Name, size, gotsize)
+		return
+	}
+	if gottype != test.Type {
+		t.Errorf("want %s value type %v, got %v", test.Name, test.Type, gottype)
+		return
+	}
+	// read data with short buffer
+	gotsize, gottype, err = k.GetValue(test.Name, make([]byte, size-1))
+	if err == nil {
+		t.Errorf("GetValue(%s, [%d]byte) should fail, but suceeded", test.Name, size-1)
+		return
+	}
+	if err != registry.ErrShortBuffer {
+		t.Errorf("reading %s value should return 'short buffer' error, but got: %s", test.Name, err)
+		return
+	}
+	if gotsize != size {
+		t.Errorf("want %s value size of %d, got %v", test.Name, size, gotsize)
+		return
+	}
+	if gottype != test.Type {
+		t.Errorf("want %s value type %v, got %v", test.Name, test.Type, gottype)
+		return
+	}
+	// read full data
+	gotsize, gottype, err = k.GetValue(test.Name, make([]byte, size))
+	if err != nil {
+		t.Errorf("GetValue(%s, [%d]byte) failed: %v", test.Name, size, err)
+		return
+	}
+	if gotsize != size {
+		t.Errorf("want %s value size of %d, got %v", test.Name, size, gotsize)
+		return
+	}
+	if gottype != test.Type {
+		t.Errorf("want %s value type %v, got %v", test.Name, test.Type, gottype)
+		return
+	}
+	// check GetValue returns ErrNotExist as required
+	_, _, err = k.GetValue(test.Name+"_not_there", make([]byte, size))
+	if err == nil {
+		t.Errorf("GetValue(%q) should not succeed", test.Name)
+		return
+	}
+	if err != registry.ErrNotExist {
+		t.Errorf("GetValue(%q) should return 'not exist' error, but got: %s", test.Name, err)
+		return
+	}
+}
+
+func testValues(t *testing.T, k registry.Key) {
+	for _, test := range ValueTests {
+		switch test.Type {
+		case registry.SZ, registry.EXPAND_SZ:
+			if test.WillFail {
+				_, _, err := k.GetStringValue(test.Name)
+				testErrNotExist(t, test.Name, err)
+			} else {
+				testGetStringValue(t, k, test)
+				_, gottype, err := k.GetIntegerValue(test.Name)
+				testErrUnexpectedType(t, test, gottype, err)
+				// Size of utf16 string in bytes is not perfect,
+				// but correct for current test values.
+				// Size also includes terminating 0.
+				testGetValue(t, k, test, (len(test.Value.(string))+1)*2)
+			}
+			_, _, err := k.GetStringValue(test.Name + "_string_not_created")
+			testErrNotExist(t, test.Name+"_string_not_created", err)
+		case registry.DWORD, registry.QWORD:
+			testGetIntegerValue(t, k, test)
+			_, gottype, err := k.GetBinaryValue(test.Name)
+			testErrUnexpectedType(t, test, gottype, err)
+			_, _, err = k.GetIntegerValue(test.Name + "_int_not_created")
+			testErrNotExist(t, test.Name+"_int_not_created", err)
+			size := 8
+			if test.Type == registry.DWORD {
+				size = 4
+			}
+			testGetValue(t, k, test, size)
+		case registry.BINARY:
+			testGetBinaryValue(t, k, test)
+			_, gottype, err := k.GetStringsValue(test.Name)
+			testErrUnexpectedType(t, test, gottype, err)
+			_, _, err = k.GetBinaryValue(test.Name + "_byte_not_created")
+			testErrNotExist(t, test.Name+"_byte_not_created", err)
+			testGetValue(t, k, test, len(test.Value.([]byte)))
+		case registry.MULTI_SZ:
+			if test.WillFail {
+				_, _, err := k.GetStringsValue(test.Name)
+				testErrNotExist(t, test.Name, err)
+			} else {
+				testGetStringsValue(t, k, test)
+				_, gottype, err := k.GetStringValue(test.Name)
+				testErrUnexpectedType(t, test, gottype, err)
+				size := 0
+				for _, s := range test.Value.([]string) {
+					size += len(s) + 1 // nil terminated
+				}
+				size += 1 // extra nil at the end
+				size *= 2 // count bytes, not uint16
+				testGetValue(t, k, test, size)
+			}
+			_, _, err := k.GetStringsValue(test.Name + "_strings_not_created")
+			testErrNotExist(t, test.Name+"_strings_not_created", err)
+		default:
+			t.Errorf("unsupported type %d for %s value", test.Type, test.Name)
+			continue
+		}
+	}
+}
+
+func testStat(t *testing.T, k registry.Key) {
+	subk, _, err := registry.CreateKey(k, "subkey", registry.CREATE_SUB_KEY)
+	if err != nil {
+		t.Error(err)
+		return
+	}
+	defer subk.Close()
+
+	defer registry.DeleteKey(k, "subkey")
+
+	ki, err := k.Stat()
+	if err != nil {
+		t.Error(err)
+		return
+	}
+	if ki.SubKeyCount != 1 {
+		t.Error("key must have 1 subkey")
+	}
+	if ki.MaxSubKeyLen != 6 {
+		t.Error("key max subkey name length must be 6")
+	}
+	if ki.ValueCount != 24 {
+		t.Errorf("key must have 24 values, but is %d", ki.ValueCount)
+	}
+	if ki.MaxValueNameLen != 12 {
+		t.Errorf("key max value name length must be 10, but is %d", ki.MaxValueNameLen)
+	}
+	if ki.MaxValueLen != 38 {
+		t.Errorf("key max value length must be 38, but is %d", ki.MaxValueLen)
+	}
+	if mt, ct := ki.ModTime(), time.Now(); ct.Sub(mt) > 100*time.Millisecond {
+		t.Errorf("key mod time is not close to current time: mtime=%v current=%v delta=%v", mt, ct, ct.Sub(mt))
+	}
+}
+
+func deleteValues(t *testing.T, k registry.Key) {
+	for _, test := range ValueTests {
+		if test.WillFail {
+			continue
+		}
+		err := k.DeleteValue(test.Name)
+		if err != nil {
+			t.Error(err)
+			continue
+		}
+	}
+	names, err := k.ReadValueNames(-1)
+	if err != nil {
+		t.Error(err)
+		return
+	}
+	if len(names) != 0 {
+		t.Errorf("some values remain after deletion: %v", names)
+	}
+}
+
+func TestValues(t *testing.T) {
+	softwareK, err := registry.OpenKey(registry.CURRENT_USER, "Software", registry.QUERY_VALUE)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer softwareK.Close()
+
+	testKName := randKeyName("TestValues_")
+
+	k, exist, err := registry.CreateKey(softwareK, testKName, registry.CREATE_SUB_KEY|registry.QUERY_VALUE|registry.SET_VALUE)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer k.Close()
+
+	if exist {
+		t.Fatalf("key %q already exists", testKName)
+	}
+
+	defer registry.DeleteKey(softwareK, testKName)
+
+	setValues(t, k)
+
+	enumerateValues(t, k)
+
+	testValues(t, k)
+
+	testStat(t, k)
+
+	deleteValues(t, k)
+}
+
+func walkKey(t *testing.T, k registry.Key, kname string) {
+	names, err := k.ReadValueNames(-1)
+	if err != nil {
+		t.Fatalf("reading value names of %s failed: %v", kname, err)
+	}
+	for _, name := range names {
+		_, valtype, err := k.GetValue(name, nil)
+		if err != nil {
+			t.Fatalf("reading value type of %s of %s failed: %v", name, kname, err)
+		}
+		switch valtype {
+		case registry.NONE:
+		case registry.SZ:
+			_, _, err := k.GetStringValue(name)
+			if err != nil {
+				t.Error(err)
+			}
+		case registry.EXPAND_SZ:
+			s, _, err := k.GetStringValue(name)
+			if err != nil {
+				t.Error(err)
+			}
+			_, err = registry.ExpandString(s)
+			if err != nil {
+				t.Error(err)
+			}
+		case registry.DWORD, registry.QWORD:
+			_, _, err := k.GetIntegerValue(name)
+			if err != nil {
+				t.Error(err)
+			}
+		case registry.BINARY:
+			_, _, err := k.GetBinaryValue(name)
+			if err != nil {
+				t.Error(err)
+			}
+		case registry.MULTI_SZ:
+			_, _, err := k.GetStringsValue(name)
+			if err != nil {
+				t.Error(err)
+			}
+		case registry.FULL_RESOURCE_DESCRIPTOR, registry.RESOURCE_LIST, registry.RESOURCE_REQUIREMENTS_LIST:
+			// TODO: not implemented
+		default:
+			t.Fatalf("value type %d of %s of %s failed: %v", valtype, name, kname, err)
+		}
+	}
+
+	names, err = k.ReadSubKeyNames(-1)
+	if err != nil {
+		t.Fatalf("reading sub-keys of %s failed: %v", kname, err)
+	}
+	for _, name := range names {
+		func() {
+			subk, err := registry.OpenKey(k, name, registry.ENUMERATE_SUB_KEYS|registry.QUERY_VALUE)
+			if err != nil {
+				if err == syscall.ERROR_ACCESS_DENIED {
+					// ignore error, if we are not allowed to access this key
+					return
+				}
+				t.Fatalf("opening sub-keys %s of %s failed: %v", name, kname, err)
+			}
+			defer subk.Close()
+
+			walkKey(t, subk, kname+`\`+name)
+		}()
+	}
+}
+
+func TestWalkFullRegistry(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping long running test in short mode")
+	}
+	walkKey(t, registry.CLASSES_ROOT, "CLASSES_ROOT")
+	walkKey(t, registry.CURRENT_USER, "CURRENT_USER")
+	walkKey(t, registry.LOCAL_MACHINE, "LOCAL_MACHINE")
+	walkKey(t, registry.USERS, "USERS")
+	walkKey(t, registry.CURRENT_CONFIG, "CURRENT_CONFIG")
+}
+
+func TestExpandString(t *testing.T) {
+	got, err := registry.ExpandString("%PATH%")
+	if err != nil {
+		t.Fatal(err)
+	}
+	want := os.Getenv("PATH")
+	if got != want {
+		t.Errorf("want %q string expanded, got %q", want, got)
+	}
+}

windows/registry/syscall.go

@@ -0,0 +1,28 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build windows
+
+package registry
+
+import "syscall"
+
+//go:generate go run $GOROOT/src/syscall/mksyscall_windows.go -output zsyscall_windows.go syscall.go
+
+const (
+	_REG_OPTION_NON_VOLATILE = 0
+
+	_REG_CREATED_NEW_KEY     = 1
+	_REG_OPENED_EXISTING_KEY = 2
+
+	_ERROR_NO_MORE_ITEMS syscall.Errno = 259
+)
+
+//sys	regCreateKeyEx(key syscall.Handle, subkey *uint16, reserved uint32, class *uint16, options uint32, desired uint32, sa *syscall.SecurityAttributes, result *syscall.Handle, disposition *uint32) (regerrno error) = advapi32.RegCreateKeyExW
+//sys	regDeleteKey(key syscall.Handle, subkey *uint16) (regerrno error) = advapi32.RegDeleteKeyW
+//sys	regSetValueEx(key syscall.Handle, valueName *uint16, reserved uint32, vtype uint32, buf *byte, bufsize uint32) (regerrno error) = advapi32.RegSetValueExW
+//sys	regEnumValue(key syscall.Handle, index uint32, name *uint16, nameLen *uint32, reserved *uint32, valtype *uint32, buf *byte, buflen *uint32) (regerrno error) = advapi32.RegEnumValueW
+//sys	regDeleteValue(key syscall.Handle, name *uint16) (regerrno error) = advapi32.RegDeleteValueW
+
+//sys	expandEnvironmentStrings(src *uint16, dst *uint16, size uint32) (n uint32, err error) = kernel32.ExpandEnvironmentStringsW

windows/registry/value.go

@@ -0,0 +1,318 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build windows
+
+package registry
+
+import (
+	"errors"
+	"io"
+	"syscall"
+	"unicode/utf16"
+	"unsafe"
+)
+
+const (
+	// Registry value types.
+	NONE                       = 0
+	SZ                         = 1
+	EXPAND_SZ                  = 2
+	BINARY                     = 3
+	DWORD                      = 4
+	DWORD_BIG_ENDIAN           = 5
+	LINK                       = 6
+	MULTI_SZ                   = 7
+	RESOURCE_LIST              = 8
+	FULL_RESOURCE_DESCRIPTOR   = 9
+	RESOURCE_REQUIREMENTS_LIST = 10
+	QWORD                      = 11
+)
+
+var (
+	// ErrShortBuffer is returned when the buffer was too short for the operation.
+	ErrShortBuffer = syscall.ERROR_MORE_DATA
+
+	// ErrNotExist is returned when a registry key or value does not exist.
+	ErrNotExist = syscall.ERROR_FILE_NOT_FOUND
+
+	// ErrUnexpectedType is returned by Get*Value when the value's type was unexpected.
+	ErrUnexpectedType = errors.New("unexpected key value type")
+)
+
+// GetValue retrieves the type and data for the specified value associated
+// with an open key k. It fills up buffer buf and returns the retrieved
+// byte count n. If buf is too small to fit the stored value it returns
+// ErrShortBuffer error along with the required buffer size n.
+// If no buffer is provided, it returns true and actual buffer size n.
+// If no buffer is provided, GetValue returns the value's type only.
+// If the value does not exist, the error returned is ErrNotExist.
+//
+// GetValue is a low level function. If value's type is known, use the appropriate
+// Get*Value function instead.
+func (k Key) GetValue(name string, buf []byte) (n int, valtype uint32, err error) {
+	pname, err := syscall.UTF16PtrFromString(name)
+	if err != nil {
+		return 0, 0, err
+	}
+	var pbuf *byte
+	if len(buf) > 0 {
+		pbuf = (*byte)(unsafe.Pointer(&buf[0]))
+	}
+	l := uint32(len(buf))
+	err = syscall.RegQueryValueEx(syscall.Handle(k), pname, nil, &valtype, pbuf, &l)
+	if err != nil {
+		return int(l), valtype, err
+	}
+	return int(l), valtype, nil
+}
+
+func (k Key) getValue(name string, buf []byte) (date []byte, valtype uint32, err error) {
+	p, err := syscall.UTF16PtrFromString(name)
+	if err != nil {
+		return nil, 0, err
+	}
+	var t uint32
+	n := uint32(len(buf))
+	for {
+		err = syscall.RegQueryValueEx(syscall.Handle(k), p, nil, &t, (*byte)(unsafe.Pointer(&buf[0])), &n)
+		if err == nil {
+			return buf[:n], t, nil
+		}
+		if err != syscall.ERROR_MORE_DATA {
+			return nil, 0, err
+		}
+		if n <= uint32(len(buf)) {
+			return nil, 0, err
+		}
+		buf = make([]byte, n)
+	}
+}
+
+// GetStringValue retrieves the string value for the specified
+// value name associated with an open key k. It also returns the value's type.
+// If value does not exist, GetStringValue returns ErrNotExist.
+// If value is not SZ or EXPAND_SZ, it will return the correct value
+// type and ErrUnexpectedType.
+func (k Key) GetStringValue(name string) (val string, valtype uint32, err error) {
+	data, typ, err2 := k.getValue(name, make([]byte, 64))
+	if err2 != nil {
+		return "", typ, err2
+	}
+	switch typ {
+	case SZ, EXPAND_SZ:
+	default:
+		return "", typ, ErrUnexpectedType
+	}
+	if len(data) == 0 {
+		return "", typ, nil
+	}
+	u := (*[1 << 10]uint16)(unsafe.Pointer(&data[0]))[:]
+	return syscall.UTF16ToString(u), typ, nil
+}
+
+// ExpandString expands environment-variable strings and replaces
+// them with the values defined for the current user.
+// Use ExpandString to expand EXPAND_SZ strings.
+func ExpandString(value string) (string, error) {
+	if value == "" {
+		return "", nil
+	}
+	for i := 0; i < len(value); i++ {
+		if value[i] == 0 {
+			return "", errors.New("string cannot have 0 inside")
+		}
+	}
+	p := utf16.Encode([]rune(value))
+	r := make([]uint16, 100)
+	for {
+		n, err := expandEnvironmentStrings(&p[0], &r[0], uint32(len(r)))
+		if err != nil {
+			return "", err
+		}
+		if n <= uint32(len(r)) {
+			u := (*[1 << 10]uint16)(unsafe.Pointer(&r[0]))[:]
+			return syscall.UTF16ToString(u), nil
+		}
+		r = make([]uint16, n)
+	}
+}
+
+// GetStringsValue retrieves the []string value for the specified
+// value name associated with an open key k. It also returns the value's type.
+// If value does not exist, GetStringsValue returns ErrNotExist.
+// If value is not MULTI_SZ, it will return the correct value
+// type and ErrUnexpectedType.
+func (k Key) GetStringsValue(name string) (val []string, valtype uint32, err error) {
+	data, typ, err2 := k.getValue(name, make([]byte, 64))
+	if err2 != nil {
+		return nil, typ, err2
+	}
+	if typ != MULTI_SZ {
+		return nil, typ, ErrUnexpectedType
+	}
+	val = make([]string, 0, 5)
+	p := (*[1 << 24]uint16)(unsafe.Pointer(&data[0]))[:len(data)/2]
+	p = p[:len(p)-1] // remove terminating nil
+	from := 0
+	for i, c := range p {
+		if c == 0 {
+			val = append(val, string(utf16.Decode(p[from:i])))
+			from = i + 1
+		}
+	}
+	return val, typ, nil
+}
+
+// GetIntegerValue retrieves the integer value for the specified
+// value name associated with an open key k. It also returns the value's type.
+// If value does not exist, GetIntegerValue returns ErrNotExist.
+// If value is not DWORD or QWORD, it will return the correct value
+// type and ErrUnexpectedType.
+func (k Key) GetIntegerValue(name string) (val uint64, valtype uint32, err error) {
+	data, typ, err2 := k.getValue(name, make([]byte, 8))
+	if err2 != nil {
+		return 0, typ, err2
+	}
+	switch typ {
+	case DWORD:
+		return uint64(*(*uint32)(unsafe.Pointer(&data[0]))), DWORD, nil
+	case QWORD:
+		return uint64(*(*uint64)(unsafe.Pointer(&data[0]))), QWORD, nil
+	default:
+		return 0, typ, ErrUnexpectedType
+	}
+}
+
+// GetBinaryValue retrieves the binary value for the specified
+// value name associated with an open key k. It also returns the value's type.
+// If value does not exist, GetBinaryValue returns ErrNotExist.
+// If value is not BINARY, it will return the correct value
+// type and ErrUnexpectedType.
+func (k Key) GetBinaryValue(name string) (val []byte, valtype uint32, err error) {
+	data, typ, err2 := k.getValue(name, make([]byte, 64))
+	if err2 != nil {
+		return nil, typ, err2
+	}
+	if typ != BINARY {
+		return nil, typ, ErrUnexpectedType
+	}
+	return data, typ, nil
+}
+
+func (k Key) setValue(name string, valtype uint32, data []byte) error {
+	p, err := syscall.UTF16PtrFromString(name)
+	if err != nil {
+		return err
+	}
+	if len(data) == 0 {
+		return regSetValueEx(syscall.Handle(k), p, 0, valtype, nil, 0)
+	}
+	return regSetValueEx(syscall.Handle(k), p, 0, valtype, &data[0], uint32(len(data)))
+}
+
+// SetDWordValue sets the data and type of a name value
+// under key k to value and DWORD.
+func (k Key) SetDWordValue(name string, value uint32) error {
+	return k.setValue(name, DWORD, (*[4]byte)(unsafe.Pointer(&value))[:])
+}
+
+// SetQWordValue sets the data and type of a name value
+// under key k to value and QWORD.
+func (k Key) SetQWordValue(name string, value uint64) error {
+	return k.setValue(name, QWORD, (*[8]byte)(unsafe.Pointer(&value))[:])
+}
+
+func (k Key) setStringValue(name string, valtype uint32, value string) error {
+	v, err := syscall.UTF16FromString(value)
+	if err != nil {
+		return err
+	}
+	buf := (*[1 << 10]byte)(unsafe.Pointer(&v[0]))[:len(v)*2]
+	return k.setValue(name, valtype, buf)
+}
+
+// SetStringValue sets the data and type of a name value
+// under key k to value and SZ. The value must not contain a zero byte.
+func (k Key) SetStringValue(name, value string) error {
+	return k.setStringValue(name, SZ, value)
+}
+
+// SetExpandStringValue sets the data and type of a name value
+// under key k to value and EXPAND_SZ. The value must not contain a zero byte.
+func (k Key) SetExpandStringValue(name, value string) error {
+	return k.setStringValue(name, EXPAND_SZ, value)
+}
+
+// SetStringsValue sets the data and type of a name value
+// under key k to value and MULTI_SZ. The value strings
+// must not contain a zero byte.
+func (k Key) SetStringsValue(name string, value []string) error {
+	ss := ""
+	for _, s := range value {
+		for i := 0; i < len(s); i++ {
+			if s[i] == 0 {
+				return errors.New("string cannot have 0 inside")
+			}
+		}
+		ss += s + "\x00"
+	}
+	v := utf16.Encode([]rune(ss + "\x00"))
+	buf := (*[1 << 10]byte)(unsafe.Pointer(&v[0]))[:len(v)*2]
+	return k.setValue(name, MULTI_SZ, buf)
+}
+
+// SetBinaryValue sets the data and type of a name value
+// under key k to value and BINARY.
+func (k Key) SetBinaryValue(name string, value []byte) error {
+	return k.setValue(name, BINARY, value)
+}
+
+// DeleteValue removes a named value from the key k.
+func (k Key) DeleteValue(name string) error {
+	return regDeleteValue(syscall.Handle(k), syscall.StringToUTF16Ptr(name))
+}
+
+// ReadValueNames returns the value names of key k.
+// The parameter n controls the number of returned names,
+// analogous to the way os.File.Readdirnames works.
+func (k Key) ReadValueNames(n int) ([]string, error) {
+	ki, err := k.Stat()
+	if err != nil {
+		return nil, err
+	}
+	names := make([]string, 0, ki.ValueCount)
+	buf := make([]uint16, ki.MaxValueNameLen+1) // extra room for terminating null character
+loopItems:
+	for i := uint32(0); ; i++ {
+		if n > 0 {
+			if len(names) == n {
+				return names, nil
+			}
+		}
+		l := uint32(len(buf))
+		for {
+			err := regEnumValue(syscall.Handle(k), i, &buf[0], &l, nil, nil, nil, nil)
+			if err == nil {
+				break
+			}
+			if err == syscall.ERROR_MORE_DATA {
+				println(len(buf), l)
+				// Double buffer size and try again.
+				l = uint32(2 * len(buf))
+				buf = make([]uint16, l)
+				continue
+			}
+			if err == _ERROR_NO_MORE_ITEMS {
+				break loopItems
+			}
+			return names, err
+		}
+		names = append(names, syscall.UTF16ToString(buf[:l]))
+	}
+	if n > len(names) {
+		return names, io.EOF
+	}
+	return names, nil
+}

windows/registry/zsyscall_windows.go

@@ -0,0 +1,73 @@
+// MACHINE GENERATED BY 'go generate' COMMAND; DO NOT EDIT
+
+package registry
+
+import "unsafe"
+import "syscall"
+
+var _ unsafe.Pointer
+
+var (
+	modadvapi32 = syscall.NewLazyDLL("advapi32.dll")
+	modkernel32 = syscall.NewLazyDLL("kernel32.dll")
+
+	procRegCreateKeyExW           = modadvapi32.NewProc("RegCreateKeyExW")
+	procRegDeleteKeyW             = modadvapi32.NewProc("RegDeleteKeyW")
+	procRegSetValueExW            = modadvapi32.NewProc("RegSetValueExW")
+	procRegEnumValueW             = modadvapi32.NewProc("RegEnumValueW")
+	procRegDeleteValueW           = modadvapi32.NewProc("RegDeleteValueW")
+	procExpandEnvironmentStringsW = modkernel32.NewProc("ExpandEnvironmentStringsW")
+)
+
+func regCreateKeyEx(key syscall.Handle, subkey *uint16, reserved uint32, class *uint16, options uint32, desired uint32, sa *syscall.SecurityAttributes, result *syscall.Handle, disposition *uint32) (regerrno error) {
+	r0, _, _ := syscall.Syscall9(procRegCreateKeyExW.Addr(), 9, uintptr(key), uintptr(unsafe.Pointer(subkey)), uintptr(reserved), uintptr(unsafe.Pointer(class)), uintptr(options), uintptr(desired), uintptr(unsafe.Pointer(sa)), uintptr(unsafe.Pointer(result)), uintptr(unsafe.Pointer(disposition)))
+	if r0 != 0 {
+		regerrno = syscall.Errno(r0)
+	}
+	return
+}
+
+func regDeleteKey(key syscall.Handle, subkey *uint16) (regerrno error) {
+	r0, _, _ := syscall.Syscall(procRegDeleteKeyW.Addr(), 2, uintptr(key), uintptr(unsafe.Pointer(subkey)), 0)
+	if r0 != 0 {
+		regerrno = syscall.Errno(r0)
+	}
+	return
+}
+
+func regSetValueEx(key syscall.Handle, valueName *uint16, reserved uint32, vtype uint32, buf *byte, bufsize uint32) (regerrno error) {
+	r0, _, _ := syscall.Syscall6(procRegSetValueExW.Addr(), 6, uintptr(key), uintptr(unsafe.Pointer(valueName)), uintptr(reserved), uintptr(vtype), uintptr(unsafe.Pointer(buf)), uintptr(bufsize))
+	if r0 != 0 {
+		regerrno = syscall.Errno(r0)
+	}
+	return
+}
+
+func regEnumValue(key syscall.Handle, index uint32, name *uint16, nameLen *uint32, reserved *uint32, valtype *uint32, buf *byte, buflen *uint32) (regerrno error) {
+	r0, _, _ := syscall.Syscall9(procRegEnumValueW.Addr(), 8, uintptr(key), uintptr(index), uintptr(unsafe.Pointer(name)), uintptr(unsafe.Pointer(nameLen)), uintptr(unsafe.Pointer(reserved)), uintptr(unsafe.Pointer(valtype)), uintptr(unsafe.Pointer(buf)), uintptr(unsafe.Pointer(buflen)), 0)
+	if r0 != 0 {
+		regerrno = syscall.Errno(r0)
+	}
+	return
+}
+
+func regDeleteValue(key syscall.Handle, name *uint16) (regerrno error) {
+	r0, _, _ := syscall.Syscall(procRegDeleteValueW.Addr(), 2, uintptr(key), uintptr(unsafe.Pointer(name)), 0)
+	if r0 != 0 {
+		regerrno = syscall.Errno(r0)
+	}
+	return
+}
+
+func expandEnvironmentStrings(src *uint16, dst *uint16, size uint32) (n uint32, err error) {
+	r0, _, e1 := syscall.Syscall(procExpandEnvironmentStringsW.Addr(), 3, uintptr(unsafe.Pointer(src)), uintptr(unsafe.Pointer(dst)), uintptr(size))
+	n = uint32(r0)
+	if n == 0 {
+		if e1 != 0 {
+			err = error(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}