windows,windows\svc,windows\svc\mgr: use unsafe.Slice instead of unsafeheader.Slice

unsafe.Slice is available since Go 1.17, which is already the minimum
version supported by this package.

This change removes the dependency on the internal unsafeheader package,
which can be removed from the module.

Change-Id: I6c34cb152f2336ea04c5f9c7e88797ed8914f9cc
Reviewed-on: https://go-review.googlesource.com/c/sys/+/526635
Run-TryBot: Quim Muntal <quimmuntal@gmail.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>

windows/security_windows.go

@@ -7,8 +7,6 @@ package windows
 import (
 	"syscall"
 	"unsafe"
-
-	"golang.org/x/sys/internal/unsafeheader"
 )
 
 const (
@@ -1341,21 +1339,14 @@ func (selfRelativeSD *SECURITY_DESCRIPTOR) copySelfRelativeSecurityDescriptor()
 		sdLen = min
 	}
 
-	var src []byte
-	h := (*unsafeheader.Slice)(unsafe.Pointer(&src))
-	h.Data = unsafe.Pointer(selfRelativeSD)
-	h.Len = sdLen
-	h.Cap = sdLen
-
+	src := unsafe.Slice((*byte)(unsafe.Pointer(selfRelativeSD)), sdLen)
+	// SECURITY_DESCRIPTOR has pointers in it, which means checkptr expects for it to
+	// be aligned properly. When we're copying a Windows-allocated struct to a
+	// Go-allocated one, make sure that the Go allocation is aligned to the
+	// pointer size.
 	const psize = int(unsafe.Sizeof(uintptr(0)))
-
-	var dst []byte
-	h = (*unsafeheader.Slice)(unsafe.Pointer(&dst))
 	alloc := make([]uintptr, (sdLen+psize-1)/psize)
-	h.Data = (*unsafeheader.Slice)(unsafe.Pointer(&alloc)).Data
-	h.Len = sdLen
-	h.Cap = sdLen
-
+	dst := unsafe.Slice((*byte)(unsafe.Pointer(&alloc[0])), sdLen)
 	copy(dst, src)
 	return (*SECURITY_DESCRIPTOR)(unsafe.Pointer(&dst[0]))
 }

windows/svc/mgr/mgr.go

@@ -17,7 +17,6 @@ import (
 	"unicode/utf16"
 	"unsafe"
 
-	"golang.org/x/sys/internal/unsafeheader"
 	"golang.org/x/sys/windows"
 )
 
@@ -199,12 +198,7 @@ func (m *Mgr) ListServices() ([]string, error) {
 	if servicesReturned == 0 {
 		return nil, nil
 	}
-
-	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)
+	services := unsafe.Slice((*windows.ENUM_SERVICE_STATUS_PROCESS)(unsafe.Pointer(&buf[0])), int(servicesReturned))
 
 	var names []string
 	for _, s := range services {

windows/svc/mgr/recovery.go

@@ -13,7 +13,6 @@ import (
 	"time"
 	"unsafe"
 
-	"golang.org/x/sys/internal/unsafeheader"
 	"golang.org/x/sys/windows"
 )
 
@@ -70,12 +69,7 @@ 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)
-
+	actions := unsafe.Slice(p.Actions, int(p.ActionsCount))
 	var recoveryActions []RecoveryAction
 	for _, action := range actions {
 		recoveryActions = append(recoveryActions, RecoveryAction{Type: int(action.Type), Delay: time.Duration(action.Delay) * time.Millisecond})

windows/svc/service.go

@@ -13,7 +13,6 @@ import (
 	"sync"
 	"unsafe"
 
-	"golang.org/x/sys/internal/unsafeheader"
 	"golang.org/x/sys/windows"
 )
 
@@ -222,11 +221,7 @@ func serviceMain(argc uint32, argv **uint16) uintptr {
 	defer func() {
 		theService.h = 0
 	}()
-	var args16 []*uint16
-	hdr := (*unsafeheader.Slice)(unsafe.Pointer(&args16))
-	hdr.Data = unsafe.Pointer(argv)
-	hdr.Len = int(argc)
-	hdr.Cap = int(argc)
+	args16 := unsafe.Slice(argv, int(argc))
 
 	args := make([]string, len(args16))
 	for i, a := range args16 {

windows/syscall_windows.go

@@ -15,8 +15,6 @@ import (
 	"time"
 	"unicode/utf16"
 	"unsafe"
-
-	"golang.org/x/sys/internal/unsafeheader"
 )
 
 type Handle uintptr
@@ -1667,12 +1665,8 @@ func NewNTUnicodeString(s string) (*NTUnicodeString, error) {
 
 // Slice returns a uint16 slice that aliases the data in the NTUnicodeString.
 func (s *NTUnicodeString) Slice() []uint16 {
-	var slice []uint16
-	hdr := (*unsafeheader.Slice)(unsafe.Pointer(&slice))
-	hdr.Data = unsafe.Pointer(s.Buffer)
-	hdr.Len = int(s.Length)
-	hdr.Cap = int(s.MaximumLength)
-	return slice
+	slice := unsafe.Slice(s.Buffer, s.MaximumLength)
+	return slice[:s.Length]
 }
 
 func (s *NTUnicodeString) String() string {
@@ -1695,12 +1689,8 @@ func NewNTString(s string) (*NTString, error) {
 
 // Slice returns a byte slice that aliases the data in the NTString.
 func (s *NTString) Slice() []byte {
-	var slice []byte
-	hdr := (*unsafeheader.Slice)(unsafe.Pointer(&slice))
-	hdr.Data = unsafe.Pointer(s.Buffer)
-	hdr.Len = int(s.Length)
-	hdr.Cap = int(s.MaximumLength)
-	return slice
+	slice := unsafe.Slice(s.Buffer, s.MaximumLength)
+	return slice[:s.Length]
 }
 
 func (s *NTString) String() string {
@@ -1752,10 +1742,7 @@ func LoadResourceData(module, resInfo Handle) (data []byte, err error) {
 	if err != nil {
 		return
 	}
-	h := (*unsafeheader.Slice)(unsafe.Pointer(&data))
-	h.Data = unsafe.Pointer(ptr)
-	h.Len = int(size)
-	h.Cap = int(size)
+	data = unsafe.Slice((*byte)(unsafe.Pointer(ptr)), size)
 	return
 }
 

windows/syscall_windows_test.go

@@ -22,7 +22,6 @@ import (
 	"time"
 	"unsafe"
 
-	"golang.org/x/sys/internal/unsafeheader"
 	"golang.org/x/sys/windows"
 )
 
@@ -865,10 +864,7 @@ func TestSystemModuleVersions(t *testing.T) {
 			return
 		}
 		mods := (*windows.RTL_PROCESS_MODULES)(unsafe.Pointer(&moduleBuffer[0]))
-		hdr := (*unsafeheader.Slice)(unsafe.Pointer(&modules))
-		hdr.Data = unsafe.Pointer(&mods.Modules[0])
-		hdr.Len = int(mods.NumberOfModules)
-		hdr.Cap = int(mods.NumberOfModules)
+		modules = unsafe.Slice(&mods.Modules[0], int(mods.NumberOfModules))
 		break
 	}
 	for i := range modules {