[PATCH 0/1] MR5437: kernelbase: Do not start the debugger if SEM_NOGPFAULTERRORBOX is set.

[PATCH 1/1] kernelbase: Do not start the debugger if SEM_NOGPFAULTERRORBOX is set.

[Zebediah Figura]

From: Zebediah Figura

Motor City Online apparently checks for a debugger by setting this flag and then
intentionally causing a page fault. If no debugger is present on Windows, the
subprocess simply dies without spawning any crash dialog. This patch emulates
that behaviour, suppressing a (harmless) crash dialog from winedbg.

This may result in legitimate failures no longer triggering a winedbg crash
dialog, if other programs happen to use SEM_NOGPFAULTERRORBOX, but the winedbg
crash dialog cannot be relied upon anyway.
---
 dlls/kernelbase/debug.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/dlls/kernelbase/debug.c b/dlls/kernelbase/debug.c
index b7df4a7c766..2f34e89c837 100644
--- a/dlls/kernelbase/debug.c
+++ b/dlls/kernelbase/debug.c
@@ -761,10 +761,11 @@ LONG WINAPI UnhandledExceptionFilter( EXCEPTION_POINTERS *epointers )
             if (ret != EXCEPTION_CONTINUE_SEARCH) return ret;
         }

-        /* FIXME: Should check the current error mode */
-
-        if (!start_debugger_atomic( epointers ) || !NtCurrentTeb()->Peb->BeingDebugged)
-            return EXCEPTION_EXECUTE_HANDLER;
+        if (!(GetErrorMode() & SEM_NOGPFAULTERRORBOX))
+        {
+            if (!start_debugger_atomic( epointers ) || !NtCurrentTeb()->Peb->BeingDebugged)
+                return EXCEPTION_EXECUTE_HANDLER;
+        }
     }
     return EXCEPTION_CONTINUE_SEARCH;
 }