time: handle localized time zone names

The existing implementation fails to determine the correct time zone
abbreviations when the display language is non-English. This change adds
support for localized time zone names (standard- and daylightname)
by using the function RegLoadMUIString.

Fixes #12015

Change-Id: Ic0dc89c50993af8f292b199c20bc5932903e7e87
Reviewed-on: https://go-review.googlesource.com/13854Reviewed-by: Alex Brainman <alex.brainman@gmail.com>
Run-TryBot: Alex Brainman <alex.brainman@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/internal/syscall/windows/registry/registry_test.go

@@ -12,6 +12,7 @@ import (
 	"os"
 	"syscall"
 	"testing"
+	"unsafe"
 
 	"internal/syscall/windows/registry"
 )
@@ -676,3 +677,74 @@ func TestInvalidValues(t *testing.T) {
 		}
 	}
 }
+
+func TestGetMUIStringValue(t *testing.T) {
+	if err := registry.LoadRegLoadMUIString(); err != nil {
+		t.Skip("regLoadMUIString not supported; skipping")
+	}
+	if err := procGetDynamicTimeZoneInformation.Find(); err != nil {
+		t.Skipf("%s not supported; skipping", procGetDynamicTimeZoneInformation.Name)
+	}
+	var dtzi DynamicTimezoneinformation
+	if _, err := GetDynamicTimeZoneInformation(&dtzi); err != nil {
+		t.Fatal(err)
+	}
+	tzKeyName := syscall.UTF16ToString(dtzi.TimeZoneKeyName[:])
+	timezoneK, err := registry.OpenKey(registry.LOCAL_MACHINE,
+		`SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones\`+tzKeyName, registry.READ)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer timezoneK.Close()
+
+	var tests = []struct {
+		key  registry.Key
+		name string
+		want string
+	}{
+		{key: timezoneK, name: "MUI_Std", want: syscall.UTF16ToString(dtzi.StandardName[:])},
+		{key: timezoneK, name: "MUI_Dlt", want: syscall.UTF16ToString(dtzi.DaylightName[:])},
+	}
+
+	for _, test := range tests {
+		got, err := test.key.GetMUIStringValue(test.name)
+		if err != nil {
+			t.Error("GetMUIStringValue:", err)
+		}
+
+		if got != test.want {
+			t.Errorf("GetMUIStringValue: %s: Got %q, want %q", test.name, got, test.want)
+		}
+	}
+}
+
+type DynamicTimezoneinformation struct {
+	Bias                        int32
+	StandardName                [32]uint16
+	StandardDate                syscall.Systemtime
+	StandardBias                int32
+	DaylightName                [32]uint16
+	DaylightDate                syscall.Systemtime
+	DaylightBias                int32
+	TimeZoneKeyName             [128]uint16
+	DynamicDaylightTimeDisabled uint8
+}
+
+var (
+	kernel32DLL = syscall.NewLazyDLL("kernel32")
+
+	procGetDynamicTimeZoneInformation = kernel32DLL.NewProc("GetDynamicTimeZoneInformation")
+)
+
+func GetDynamicTimeZoneInformation(dtzi *DynamicTimezoneinformation) (rc uint32, err error) {
+	r0, _, e1 := syscall.Syscall(procGetDynamicTimeZoneInformation.Addr(), 1, uintptr(unsafe.Pointer(dtzi)), 0, 0)
+	rc = uint32(r0)
+	if rc == 0xffffffff {
+		if e1 != 0 {
+			err = error(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}

src/internal/syscall/windows/registry/syscall.go

@@ -19,10 +19,15 @@ const (
 	_ERROR_NO_MORE_ITEMS syscall.Errno = 259
 )
 
+func LoadRegLoadMUIString() error {
+	return procRegLoadMUIStringW.Find()
+}
+
 //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   regLoadMUIString(key syscall.Handle, name *uint16, buf *uint16, buflen uint32, buflenCopied *uint32, flags uint32, dir *uint16) (regerrno error) = advapi32.RegLoadMUIStringW
 
 //sys	expandEnvironmentStrings(src *uint16, dst *uint16, size uint32) (n uint32, err error) = kernel32.ExpandEnvironmentStringsW

src/internal/syscall/windows/registry/value.go

@@ -112,6 +112,53 @@ func (k Key) GetStringValue(name string) (val string, valtype uint32, err error)
 	return syscall.UTF16ToString(u), typ, nil
 }
 
+// GetMUIStringValue retrieves the localized string value for
+// the specified value name associated with an open key k.
+// If the value name doesn't exist or the localized string value
+// can't be resolved, GetMUIStringValue returns ErrNotExist.
+// GetMUIStringValue panics if the system doesn't support
+// regLoadMUIString; use LoadRegLoadMUIString to check if
+// regLoadMUIString is supported before calling this function.
+func (k Key) GetMUIStringValue(name string) (string, error) {
+	pname, err := syscall.UTF16PtrFromString(name)
+	if err != nil {
+		return "", err
+	}
+
+	buf := make([]uint16, 1024)
+	var buflen uint32
+	var pdir *uint16
+
+	err = regLoadMUIString(syscall.Handle(k), pname, &buf[0], uint32(len(buf)), &buflen, 0, pdir)
+	if err == syscall.ERROR_FILE_NOT_FOUND { // Try fallback path
+		var s string
+		s, err = ExpandString("%SystemRoot%\\system32\\")
+		if err != nil {
+			return "", err
+		}
+		pdir, err = syscall.UTF16PtrFromString(s)
+		if err != nil {
+			return "", err
+		}
+
+		err = regLoadMUIString(syscall.Handle(k), pname, &buf[0], uint32(len(buf)), &buflen, 0, pdir)
+	}
+
+	for err == syscall.ERROR_MORE_DATA { // Grow buffer if needed
+		if buflen <= uint32(len(buf)) {
+			break // Buffer not growing, assume race; break
+		}
+		buf = make([]uint16, buflen)
+		err = regLoadMUIString(syscall.Handle(k), pname, &buf[0], uint32(len(buf)), &buflen, 0, pdir)
+	}
+
+	if err != nil {
+		return "", err
+	}
+
+	return syscall.UTF16ToString(buf), nil
+}
+
 // ExpandString expands environment-variable strings and replaces
 // them with the values defined for the current user.
 // Use ExpandString to expand EXPAND_SZ strings.

src/internal/syscall/windows/registry/zsyscall_windows.go

@@ -16,6 +16,7 @@ var (
 	procRegSetValueExW            = modadvapi32.NewProc("RegSetValueExW")
 	procRegEnumValueW             = modadvapi32.NewProc("RegEnumValueW")
 	procRegDeleteValueW           = modadvapi32.NewProc("RegDeleteValueW")
+	procRegLoadMUIStringW         = modadvapi32.NewProc("RegLoadMUIStringW")
 	procExpandEnvironmentStringsW = modkernel32.NewProc("ExpandEnvironmentStringsW")
 )
 
@@ -59,6 +60,14 @@ func regDeleteValue(key syscall.Handle, name *uint16) (regerrno error) {
 	return
 }
 
+func regLoadMUIString(key syscall.Handle, name *uint16, buf *uint16, buflen uint32, buflenCopied *uint32, flags uint32, dir *uint16) (regerrno error) {
+	r0, _, _ := syscall.Syscall9(procRegLoadMUIStringW.Addr(), 7, uintptr(key), uintptr(unsafe.Pointer(name)), uintptr(unsafe.Pointer(buf)), uintptr(buflen), uintptr(unsafe.Pointer(buflenCopied)), uintptr(flags), uintptr(unsafe.Pointer(dir)), 0, 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)

src/time/zoneinfo_windows.go

@@ -20,8 +20,9 @@ import (
 // The implementation assumes that this year's rules for daylight savings
 // time apply to all previous and future years as well.
 
-// matchZoneKey checks if stdname and dstname match the corresponding "Std"
-// and "Dlt" key values in the kname key stored under the open registry key zones.
+// matchZoneKey checks if stdname and dstname match the corresponding key
+// values "MUI_Std" and MUI_Dlt" or "Std" and "Dlt" (the latter down-level
+// from Vista) in the kname key stored under the open registry key zones.
 func matchZoneKey(zones registry.Key, kname string, stdname, dstname string) (matched bool, err2 error) {
 	k, err := registry.OpenKey(zones, kname, registry.READ)
 	if err != nil {
@@ -29,18 +30,27 @@ func matchZoneKey(zones registry.Key, kname string, stdname, dstname string) (ma
 	}
 	defer k.Close()
 
-	s, _, err := k.GetStringValue("Std")
-	if err != nil {
-		return false, err
+	var std, dlt string
+	if err = registry.LoadRegLoadMUIString(); err == nil {
+		// Try MUI_Std and MUI_Dlt first, fallback to Std and Dlt if *any* error occurs
+		std, err = k.GetMUIStringValue("MUI_Std")
+		if err == nil {
+			dlt, err = k.GetMUIStringValue("MUI_Dlt")
+		}
 	}
-	if s != stdname {
-		return false, nil
+	if err != nil { // Fallback to Std and Dlt
+		if std, _, err = k.GetStringValue("Std"); err != nil {
+			return false, err
+		}
+		if dlt, _, err = k.GetStringValue("Dlt"); err != nil {
+			return false, err
+		}
 	}
-	s, _, err = k.GetStringValue("Dlt")
-	if err != nil {
-		return false, err
+
+	if std != stdname {
+		return false, nil
 	}
-	if s != dstname && dstname != stdname {
+	if dlt != dstname && dstname != stdname {
 		return false, nil
 	}
 	return true, nil

src/time/zoneinfo_windows_test.go

@@ -42,14 +42,24 @@ func TestToEnglishName(t *testing.T) {
 		t.Fatalf("cannot open CEST time zone information from registry: %s", err)
 	}
 	defer k.Close()
-	std, _, err := k.GetStringValue("Std")
-	if err != nil {
-		t.Fatalf("cannot read CEST Std registry key: %s", err)
+
+	var std, dlt string
+	if err = registry.LoadRegLoadMUIString(); err == nil {
+		// Try MUI_Std and MUI_Dlt first, fallback to Std and Dlt if *any* error occurs
+		std, err = k.GetMUIStringValue("MUI_Std")
+		if err == nil {
+			dlt, err = k.GetMUIStringValue("MUI_Dlt")
+		}
 	}
-	dlt, _, err := k.GetStringValue("Dlt")
-	if err != nil {
-		t.Fatalf("cannot read CEST Dlt registry key: %s", err)
+	if err != nil { // Fallback to Std and Dlt
+		if std, _, err = k.GetStringValue("Std"); err != nil {
+			t.Fatalf("cannot read CEST Std registry key: %s", err)
+		}
+		if dlt, _, err = k.GetStringValue("Dlt"); err != nil {
+			t.Fatalf("cannot read CEST Dlt registry key: %s", err)
+		}
 	}
+
 	name, err := ToEnglishName(std, dlt)
 	if err != nil {
 		t.Fatalf("toEnglishName failed: %s", err)