From c5c43d99f35c72567e5b84238c8ce06bd984d14b Mon Sep 17 00:00:00 2001
From: Quantum <quantum2048@gmail.com>
Date: Sat, 16 Jan 2021 07:41:28 -0500
Subject: [PATCH] [host] windows: allow capture of login screen

WTSGetActiveConsoleSessionId will return a session even if it's not logged in,
unlike our old GetInteractiveSessionID function. Launching looking glass on
such a console session will allow the login screen to be captured.

Note that WTSGetActiveConsoleSessionId() will return 0xFFFFFFFF if there are
no sessions attached.
---
 host/platform/Windows/src/service.c | 28 +++-------------------------
 1 file changed, 3 insertions(+), 25 deletions(-)

diff --git a/host/platform/Windows/src/service.c b/host/platform/Windows/src/service.c
index 80e1241d..1d5b85af 100644
--- a/host/platform/Windows/src/service.c
+++ b/host/platform/Windows/src/service.c
@@ -247,29 +247,6 @@ err_proc:
   return NULL;
 }
 
-DWORD GetInteractiveSessionID(void)
-{
-  PWTS_SESSION_INFO pSessionInfo;
-  DWORD count;
-  DWORD ret = 0;
-
-  if (!WTSEnumerateSessions(WTS_CURRENT_SERVER_HANDLE, 0, 1, &pSessionInfo,
-        &count))
-    return 0;
-
-  for(DWORD i = 0; i < count; ++i)
-  {
-    if (pSessionInfo[i].State == WTSActive)
-    {
-      ret = pSessionInfo[i].SessionId;
-      break;
-    }
-  }
-
-  WTSFreeMemory(pSessionInfo);
-  return ret;
-}
-
 void Launch(void)
 {
   if (service.process)
@@ -301,7 +278,7 @@ void Launch(void)
   if (!enablePriv(SE_TCB_NAME))
     goto fail_token;
 
-  targetSessionID = GetInteractiveSessionID();
+  targetSessionID = WTSGetActiveConsoleSessionId();
   if (origSessionID != targetSessionID)
   {
     if (!SetTokenInformation(hToken, TokenSessionId,
@@ -669,7 +646,8 @@ VOID WINAPI SvcMain(DWORD dwArgc, LPTSTR *lpszArgv)
   {
     ULONGLONG launchTime;
 
-    if (GetInteractiveSessionID() != 0)
+    DWORD interactiveSession = WTSGetActiveConsoleSessionId();
+    if (interactiveSession != 0 && interactiveSession != 0xFFFFFFFF)
     {
       Launch();
       launchTime = GetTickCount64();