windows: use unsafeheader.Slice

windows/security_windows.go

@@ -7,6 +7,8 @@ package windows
 import (
 	"syscall"
 	"unsafe"
+
+	"golang.org/x/sys/internal/unsafeheader"
 )
 
 const (
@@ -1230,7 +1232,13 @@ func (sd *SECURITY_DESCRIPTOR) String() string {
 		return ""
 	}
 	defer LocalFree(Handle(unsafe.Pointer(sddl)))
-	return UTF16PtrToString(sddl)
+
+	var utf16s []uint16
+	h := (*unsafeheader.Slice)(unsafe.Pointer(&utf16s))
+	h.Data = unsafe.Pointer(sddl)
+	h.Len = int(strLen)
+	h.Cap = int(strLen)
+	return UTF16ToString(utf16s)
 }
 
 // ToAbsolute converts a self-relative security descriptor into an absolute one.
@@ -1308,9 +1316,14 @@ func (absoluteSD *SECURITY_DESCRIPTOR) ToSelfRelative() (selfRelativeSD *SECURIT
 }
 
 func (selfRelativeSD *SECURITY_DESCRIPTOR) copySelfRelativeSecurityDescriptor() *SECURITY_DESCRIPTOR {
-	sdBytes := make([]byte, selfRelativeSD.Length())
-	copy(sdBytes, (*[(1 << 31) - 1]byte)(unsafe.Pointer(selfRelativeSD))[:len(sdBytes):len(sdBytes)])
-	return (*SECURITY_DESCRIPTOR)(unsafe.Pointer(&sdBytes[0]))
+	var dst, src []byte
+	dst = make([]byte, selfRelativeSD.Length())
+	h := (*unsafeheader.Slice)(unsafe.Pointer(&src))
+	h.Data = unsafe.Pointer(selfRelativeSD)
+	h.Len = len(dst)
+	h.Cap = len(dst)
+	copy(dst, src)
+	return (*SECURITY_DESCRIPTOR)(unsafe.Pointer(&dst[0]))
 }
 
 // SecurityDescriptorFromString converts an SDDL string describing a security descriptor into a

windows/svc/mgr/mgr.go

@@ -17,6 +17,7 @@ import (
 	"unicode/utf16"
 	"unsafe"
 
+	"golang.org/x/sys/internal/unsafeheader"
 	"golang.org/x/sys/windows"
 )
 
@@ -201,7 +202,13 @@ func (m *Mgr) ListServices() ([]string, error) {
 	if servicesReturned == 0 {
 		return nil, nil
 	}
-	services := (*[1 << 20]windows.ENUM_SERVICE_STATUS_PROCESS)(unsafe.Pointer(&buf[0]))[:servicesReturned:servicesReturned]
+
+	var services []windows.ENUM_SERVICE_STATUS_PROCESS
+	hdr := (*unsafeheader.Slice)(unsafe.Pointer(&services))
+	hdr.Data = unsafe.Pointer(&buf[0])
+	hdr.Len = int(servicesReturned)
+	hdr.Cap = int(servicesReturned)
+
 	var names []string
 	for _, s := range services {
 		name := windows.UTF16PtrToString(s.ServiceName)

windows/svc/mgr/recovery.go

@@ -12,6 +12,7 @@ import (
 	"time"
 	"unsafe"
 
+	"golang.org/x/sys/internal/unsafeheader"
 	"golang.org/x/sys/windows"
 )
 
@@ -68,8 +69,13 @@ func (s *Service) RecoveryActions() ([]RecoveryAction, error) {
 		return nil, err
 	}
 
+	var actions []windows.SC_ACTION
+	hdr := (*unsafeheader.Slice)(unsafe.Pointer(&actions))
+	hdr.Data = unsafe.Pointer(p.Actions)
+	hdr.Len = int(p.ActionsCount)
+	hdr.Cap = int(p.ActionsCount)
+
 	var recoveryActions []RecoveryAction
-	actions := (*[1024]windows.SC_ACTION)(unsafe.Pointer(p.Actions))[:p.ActionsCount:p.ActionsCount]
 	for _, action := range actions {
 		recoveryActions = append(recoveryActions, RecoveryAction{Type: int(action.Type), Delay: time.Duration(action.Delay) * time.Millisecond})
 	}

windows/svc/service.go

@@ -14,6 +14,7 @@ import (
 	"syscall"
 	"unsafe"
 
+	"golang.org/x/sys/internal/unsafeheader"
 	"golang.org/x/sys/windows"
 )
 
@@ -224,7 +225,13 @@ const (
 func (s *service) run() {
 	s.goWaits.Wait()
 	s.h = windows.Handle(ssHandle)
-	argv := (*[100]*uint16)(unsafe.Pointer(sArgv))[:sArgc:sArgc]
+
+	var argv []*uint16
+	hdr := (*unsafeheader.Slice)(unsafe.Pointer(&argv))
+	hdr.Data = unsafe.Pointer(sArgv)
+	hdr.Len = int(sArgc)
+	hdr.Cap = int(sArgc)
+
 	args := make([]string, len(argv))
 	for i, a := range argv {
 		args[i] = windows.UTF16PtrToString(a)

windows/syscall_windows.go

@@ -8,12 +8,13 @@ package windows
 
 import (
 	errorspkg "errors"
-	"strings"
 	"sync"
 	"syscall"
 	"time"
 	"unicode/utf16"
 	"unsafe"
+
+	"golang.org/x/sys/internal/unsafeheader"
 )
 
 type Handle uintptr
@@ -125,25 +126,19 @@ func UTF16PtrToString(p *uint16) string {
 	if p == nil {
 		return ""
 	}
-
-	var sb strings.Builder
-
-	for r := rune(*p); r != 0; r = rune(*p) {
-		if !utf16.IsSurrogate(r) {
-			sb.WriteRune(r)
-		} else {
-			p = (*uint16)(unsafe.Pointer(uintptr(unsafe.Pointer(p)) + unsafe.Sizeof(*p)))
-			sb.WriteRune(utf16.DecodeRune(r, rune(*p)))
-
-			if *p == 0 {
-				break
-			}
-		}
-
-		p = (*uint16)(unsafe.Pointer(uintptr(unsafe.Pointer(p)) + unsafe.Sizeof(*p)))
+	// Find NUL terminator.
+	n := 0
+	for ptr := unsafe.Pointer(p); *(*uint16)(ptr) != 0; n++ {
+		ptr = unsafe.Pointer(uintptr(ptr) + unsafe.Sizeof(*p))
 	}
 
-	return sb.String()
+	var s []uint16
+	h := (*unsafeheader.Slice)(unsafe.Pointer(&s))
+	h.Data = unsafe.Pointer(p)
+	h.Len = n
+	h.Cap = n
+
+	return string(utf16.Decode(s))
 }
 
 func Getpagesize() int { return 4096 }