os: TempDir uses GetTempPath2 on Windows if available

This generates GetTempPath2 together with RtlGetNtVersionNumbers. The
latter is needed to determine if the running Windows has GetTempPath2
by comparing it against the minimum build number that has the API.
RtlGetNtVersionNumbers was generated into syscall/windows since
syscall is locked down.

Fixes golang#56899

src/internal/syscall/windows/syscall_windows.go

@@ -151,6 +151,7 @@ const (
 //sys	GetModuleFileName(module syscall.Handle, fn *uint16, len uint32) (n uint32, err error) = kernel32.GetModuleFileNameW
 //sys	SetFileInformationByHandle(handle syscall.Handle, fileInformationClass uint32, buf uintptr, bufsize uint32) (err error) = kernel32.SetFileInformationByHandle
 //sys	VirtualQuery(address uintptr, buffer *MemoryBasicInformation, length uintptr) (err error) = kernel32.VirtualQuery
+//sys	GetTempPath2(buflen uint32, buf *uint16) (n uint32, err error) = GetTempPath2W
 
 const (
 	// flags for CreateToolhelp32Snapshot
@@ -363,6 +364,13 @@ func LoadGetFinalPathNameByHandle() error {
 	return procGetFinalPathNameByHandleW.Find()
 }
 
+func LoadGetTempPath2() bool {
+	if err := procGetTempPath2W.Find(); err != nil {
+		return false
+	}
+	return true
+}
+
 //sys	CreateEnvironmentBlock(block **uint16, token syscall.Token, inheritExisting bool) (err error) = userenv.CreateEnvironmentBlock
 //sys	DestroyEnvironmentBlock(block *uint16) (err error) = userenv.DestroyEnvironmentBlock
 

src/os/file_windows.go

@@ -14,6 +14,14 @@ import (
 	"unsafe"
 )
 
+var (
+	tempPath2Exists bool
+)
+
+func init() {
+	tempPath2Exists = windows.LoadGetTempPath2()
+}
+
 // file is the real representation of *File.
 // The extra level of indirection ensures that no clients of os
 // can overwrite this data, which could cause the finalizer
@@ -300,10 +308,14 @@ func Pipe() (r *File, w *File, err error) {
 }
 
 func tempDir() string {
+	getTempPath := syscall.GetTempPath
+	if tempPath2Exists {
+		getTempPath = windows.GetTempPath2
+	}
 	n := uint32(syscall.MAX_PATH)
 	for {
 		b := make([]uint16, n)
-		n, _ = syscall.GetTempPath(uint32(len(b)), &b[0])
+		n, _ = getTempPath(uint32(len(b)), &b[0])
 		if n > uint32(len(b)) {
 			continue
 		}