windows: UTF16PtrToString remove max parameter

windows/env_windows.go

@@ -39,7 +39,7 @@ func (token Token) Environ(inheritExisting bool) (env []string, err error) {
 	defer DestroyEnvironmentBlock(block)
 	blockp := uintptr(unsafe.Pointer(block))
 	for {
-		entry := UTF16PtrToString((*uint16)(unsafe.Pointer(blockp)), (1<<30)-1)
+		entry := UTF16PtrToString((*uint16)(unsafe.Pointer(blockp)))
 		if len(entry) == 0 {
 			break
 		}

windows/security_windows.go

@@ -1230,7 +1230,7 @@ func (sd *SECURITY_DESCRIPTOR) String() string {
 		return ""
 	}
 	defer LocalFree(Handle(unsafe.Pointer(sddl)))
-	return UTF16PtrToString(sddl, int(strLen))
+	return UTF16PtrToString(sddl)
 }
 
 // ToAbsolute converts a self-relative security descriptor into an absolute one.

windows/svc/mgr/config.go

@@ -45,26 +45,19 @@ type Config struct {
 	DelayedAutoStart bool   // the service is started after other auto-start services are started plus a short delay
 }
 
-func toString(p *uint16) string {
-	return windows.UTF16PtrToString(p, 4096)
-}
-
 func toStringSlice(ps *uint16) []string {
 	r := make([]string, 0)
 	p := unsafe.Pointer(ps)
 
-	offset := func(count int) uintptr {
-		return unsafe.Sizeof(uint16(0)) * (uintptr)(count)
-	}
-
 	for {
-		s := windows.UTF16PtrToString((*uint16)(p), 4096)
-		if s == "" {
+		s := windows.UTF16PtrToString((*uint16)(p))
+		if len(s) == 0 {
 			break
 		}
 
 		r = append(r, s)
-		p = unsafe.Pointer(uintptr(p) + offset(len(s)+1))
+		offset := unsafe.Sizeof(uint16(0)) * (uintptr)(len(s)+1)
+		p = unsafe.Pointer(uintptr(p) + offset)
 	}
 
 	return r
@@ -109,13 +102,13 @@ func (s *Service) Config() (Config, error) {
 		ServiceType:      p.ServiceType,
 		StartType:        p.StartType,
 		ErrorControl:     p.ErrorControl,
-		BinaryPathName:   toString(p.BinaryPathName),
-		LoadOrderGroup:   toString(p.LoadOrderGroup),
+		BinaryPathName:   windows.UTF16PtrToString(p.BinaryPathName),
+		LoadOrderGroup:   windows.UTF16PtrToString(p.LoadOrderGroup),
 		TagId:            p.TagId,
 		Dependencies:     toStringSlice(p.Dependencies),
-		ServiceStartName: toString(p.ServiceStartName),
-		DisplayName:      toString(p.DisplayName),
-		Description:      toString(p2.Description),
+		ServiceStartName: windows.UTF16PtrToString(p.ServiceStartName),
+		DisplayName:      windows.UTF16PtrToString(p.DisplayName),
+		Description:      windows.UTF16PtrToString(p2.Description),
 		DelayedAutoStart: delayedStart,
 	}, nil
 }

windows/svc/mgr/mgr.go

@@ -73,7 +73,7 @@ func (m *Mgr) LockStatus() (*LockStatus, error) {
 		status := &LockStatus{
 			IsLocked: lockStatus.IsLocked != 0,
 			Age:      time.Duration(lockStatus.LockDuration) * time.Second,
-			Owner:    toString(lockStatus.LockOwner),
+			Owner:    windows.UTF16PtrToString(lockStatus.LockOwner),
 		}
 		return status, nil
 	}
@@ -204,7 +204,7 @@ func (m *Mgr) ListServices() ([]string, error) {
 	services := (*[1 << 20]windows.ENUM_SERVICE_STATUS_PROCESS)(unsafe.Pointer(&buf[0]))[:servicesReturned:servicesReturned]
 	var names []string
 	for _, s := range services {
-		name := toString(s.ServiceName)
+		name := windows.UTF16PtrToString(s.ServiceName)
 		names = append(names, name)
 	}
 	return names, nil

windows/svc/mgr/recovery.go

@@ -112,7 +112,7 @@ func (s *Service) RebootMessage() (string, error) {
 		return "", err
 	}
 	p := (*windows.SERVICE_FAILURE_ACTIONS)(unsafe.Pointer(&b[0]))
-	return toString(p.RebootMsg), nil
+	return windows.UTF16PtrToString(p.RebootMsg), nil
 }
 
 // SetRecoveryCommand sets the command line of the process to execute in response to the RunCommand service controller action.
@@ -131,5 +131,5 @@ func (s *Service) RecoveryCommand() (string, error) {
 		return "", err
 	}
 	p := (*windows.SERVICE_FAILURE_ACTIONS)(unsafe.Pointer(&b[0]))
-	return toString(p.Command), nil
+	return windows.UTF16PtrToString(p.Command), nil
 }

windows/svc/service.go

@@ -227,7 +227,7 @@ func (s *service) run() {
 	argv := (*[100]*uint16)(unsafe.Pointer(sArgv))[:sArgc:sArgc]
 	args := make([]string, len(argv))
 	for i, a := range argv {
-		args[i] = windows.UTF16PtrToString(a, 1<<20)
+		args[i] = windows.UTF16PtrToString(a)
 	}
 
 	cmdsToHandler := make(chan ChangeRequest)

windows/syscall_windows.go

@@ -117,23 +117,22 @@ func UTF16PtrFromString(s string) (*uint16, error) {
 	return &a[0], nil
 }
 
-// UTF16PtrToString is like UTF16ToString, but takes *uint16
-// as a parameter instead of []uint16.
-// max is how many times p can be advanced looking for the null terminator.
-// If max is hit, the string is truncated at that point.
-func UTF16PtrToString(p *uint16, max int) string {
+// UTF16PtrToString takes a pointer to a UTF-16 sequence and returns the corresponding UTF-8 encoded string.
+// If the pointer is nil, this returns the empty string. This assumes that the UTF-16 sequence is terminated
+// at a zero word; if the zero word is not present, the program may crash.
+func UTF16PtrToString(p *uint16) string {
 	if p == nil {
 		return ""
 	}
-	// Find NUL terminator.
-	end := unsafe.Pointer(p)
-	n := 0
-	for *(*uint16)(end) != 0 && n < max {
-		end = unsafe.Pointer(uintptr(end) + unsafe.Sizeof(*p))
-		n++
+
+	var encoded []uint16
+	for *p != 0 {
+		encoded = append(encoded, *p)
+
+		p = (*uint16)(unsafe.Pointer(uintptr(unsafe.Pointer(p)) + unsafe.Sizeof(*p)))
 	}
-	s := (*[(1 << 30) - 1]uint16)(unsafe.Pointer(p))[:n:n]
-	return string(utf16.Decode(s))
+
+	return string(utf16.Decode(encoded))
 }
 
 func Getpagesize() int { return 4096 }
@@ -1402,7 +1401,7 @@ func (t Token) KnownFolderPath(folderID *KNOWNFOLDERID, flags uint32) (string, e
 		return "", err
 	}
 	defer CoTaskMemFree(unsafe.Pointer(p))
-	return UTF16PtrToString(p, (1<<30)-1), nil
+	return UTF16PtrToString(p), nil
 }
 
 // RtlGetVersion returns the version of the underlying operating system, ignoring