Fix bdist_wininst --user-access-control for win2k

PC/bdist_wininst/install.c

@@ -2115,11 +2115,6 @@ BOOL NeedAutoUAC()
 {
 	HKEY hk;
 	char key_name[80];
-	OSVERSIONINFO winverinfo;
-	winverinfo.dwOSVersionInfoSize = sizeof(winverinfo);
-	// If less than XP, then we can't do it (and its not necessary).
-	if (!GetVersionEx(&winverinfo) || winverinfo.dwMajorVersion < 5)
-		return FALSE;
 	// no Python version info == we can't know yet.
 	if (target_version[0] == '\0')
 		return FALSE;
@@ -2135,6 +2130,23 @@ BOOL NeedAutoUAC()
 	return TRUE;
 }
 
+// Returns TRUE if the platform supports UAC.
+BOOL PlatformSupportsUAC()
+{
+	// Note that win2k does seem to support ShellExecute with 'runas',
+	// but does *not* support IsUserAnAdmin - so we just pretend things
+	// only work on XP and later.
+	BOOL bIsWindowsXPorLater;
+	OSVERSIONINFO winverinfo;
+	winverinfo.dwOSVersionInfoSize = sizeof(winverinfo);
+	if (!GetVersionEx(&winverinfo))
+		return FALSE; // something bad has gone wrong
+	bIsWindowsXPorLater = 
+       ( (winverinfo.dwMajorVersion > 5) ||
+       ( (winverinfo.dwMajorVersion == 5) && (winverinfo.dwMinorVersion >= 1) ));
+	return bIsWindowsXPorLater;
+}
+
 // Spawn ourself as an elevated application.  On failure, a message is
 // displayed to the user - but this app will always terminate, even
 // on error.
@@ -2190,7 +2202,7 @@ int DoInstall(void)
 
 	// See if we need to do the Vista UAC magic.
 	if (strcmp(user_access_control, "force")==0) {
-		if (!MyIsUserAnAdmin()) {
+		if (PlatformSupportsUAC() && !MyIsUserAnAdmin()) {
 			SpawnUAC();
 			return 0;
 		}
@@ -2198,7 +2210,7 @@ int DoInstall(void)
 	} else if (strcmp(user_access_control, "auto")==0) {
 		// Check if it looks like we need UAC control, based
 		// on how Python itself was installed.
-		if (!MyIsUserAnAdmin() && NeedAutoUAC()) {
+		if (PlatformSupportsUAC() && !MyIsUserAnAdmin() && NeedAutoUAC()) {
 			SpawnUAC();
 			return 0;
 		}