windows: do not query library for inline functions

The GetCurrent*Token variety of functions are actually implemented as
inline functions in the header files of the SDK. Attempting to call out
to these as library functions is an error. This commit also adds a test
to ensure that these work as expected.

Change-Id: I105f1ca1a8936114fe61bc22188200c31f240a23
Reviewed-on: https://go-review.googlesource.com/c/sys/+/177840
Run-TryBot: Jason Donenfeld <Jason@zx2c4.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

windows/syscall_windows_test.go

@@ -8,6 +8,7 @@ import (
 	"io/ioutil"
 	"os"
 	"path/filepath"
+	"runtime"
 	"syscall"
 	"testing"
 
@@ -104,3 +105,67 @@ func TestCreateWellKnownSid(t *testing.T) {
 		t.Fatalf("Expecting administrators to be S-1-5-32-544, but found %s instead", sidStr)
 	}
 }
+
+func TestPseudoTokens(t *testing.T) {
+	version, err := windows.GetVersion()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if ((version&0xffff)>>8)|((version&0xff)<<8) < 0x0602 {
+		return
+	}
+
+	realProcessToken, err := windows.OpenCurrentProcessToken()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer realProcessToken.Close()
+	realProcessUser, err := realProcessToken.GetTokenUser()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	pseudoProcessToken := windows.GetCurrentProcessToken()
+	pseudoProcessUser, err := pseudoProcessToken.GetTokenUser()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !windows.EqualSid(realProcessUser.User.Sid, pseudoProcessUser.User.Sid) {
+		t.Fatal("The real process token does not have the same as the pseudo process token")
+	}
+
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
+
+	err = windows.RevertToSelf()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	pseudoThreadToken := windows.GetCurrentThreadToken()
+	_, err = pseudoThreadToken.GetTokenUser()
+	if err != windows.ERROR_NO_TOKEN {
+		t.Fatal("Expected an empty thread token")
+	}
+	pseudoThreadEffectiveToken := windows.GetCurrentThreadEffectiveToken()
+	pseudoThreadEffectiveUser, err := pseudoThreadEffectiveToken.GetTokenUser()
+	if err != nil {
+		t.Fatal(nil)
+	}
+	if !windows.EqualSid(realProcessUser.User.Sid, pseudoThreadEffectiveUser.User.Sid) {
+		t.Fatal("The real process token does not have the same as the pseudo thread effective token, even though we aren't impersonating")
+	}
+
+	err = windows.ImpersonateSelf(windows.SecurityImpersonation)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer windows.RevertToSelf()
+	pseudoThreadUser, err := pseudoThreadToken.GetTokenUser()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !windows.EqualSid(realProcessUser.User.Sid, pseudoThreadUser.User.Sid) {
+		t.Fatal("The real process token does not have the same as the pseudo thread token after impersonating self")
+	}
+}