From db69a9a7e1f5d25bf7ab735758650f99a99e2e39 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Herm=C3=A8s=20B=C3=A9lusca-Ma=C3=AFto?=
 <hermes.belusca-maito@reactos.org>
Date: Wed, 27 Aug 2025 23:00:59 +0200
Subject: [PATCH] [RTL][NDK] Improve RtlUnhandledExceptionFilter(2) (#8353)

- Reimplement `RtlUnhandledExceptionFilter()` by just calling
  `RtlUnhandledExceptionFilter2()`.

- Return an adequate exception filter value `EXCEPTION_CONTINUE_SEARCH`
  from `RtlUnhandledExceptionFilter2()`, instead of some random error.
  If `ExceptionCode` is `STATUS_POSSIBLE_DEADLOCK` however, return
  `EXCEPTION_CONTINUE_EXECUTION` instead, as shown by a test from Whindmar Saksit.

- The second parameter of `RtlUnhandledExceptionFilter2()` is not
  a flag, but a pointer to string `PCSTR` !
  See https://skanthak.hier-im-netz.de/download/NTDLL.H
  who is the only one online who has the correct definition,
  whose usage I've double-checked on Win7 ntdll.dll.

  This is used in the `<function_name>` slot in the displayed
  debugger message:
  ```
  *** An Access Violation occurred in <program_command_line>:<function_name>
  The instruction at <address> tried to write to a NULL pointer
  ```
  For example, see: https://community.osr.com/t/access-violation/33435
---
 sdk/include/ndk/rtlfuncs.h |  2 +-
 sdk/lib/rtl/exception.c    | 23 +++++++++++++----------
 2 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/sdk/include/ndk/rtlfuncs.h b/sdk/include/ndk/rtlfuncs.h
index 20913ab01d2..d49ba84c53c 100644
--- a/sdk/include/ndk/rtlfuncs.h
+++ b/sdk/include/ndk/rtlfuncs.h
@@ -676,7 +676,7 @@ NTSYSAPI
 LONG
 NTAPI
 RtlUnhandledExceptionFilter(
-    _In_ struct _EXCEPTION_POINTERS* ExceptionInfo
+    _In_ PEXCEPTION_POINTERS ExceptionInfo
 );
 
 __analysis_noreturn
diff --git a/sdk/lib/rtl/exception.c b/sdk/lib/rtl/exception.c
index 63a65e884b5..6ea7fc58a1c 100644
--- a/sdk/lib/rtl/exception.c
+++ b/sdk/lib/rtl/exception.c
@@ -87,7 +87,7 @@ RtlRaiseStatus(IN NTSTATUS Status)
     EXCEPTION_RECORD ExceptionRecord;
     CONTEXT Context;
 
-     /* Capture the context */
+    /* Capture the context */
     RtlCaptureContext(&Context);
 
     /* Create an exception record */
@@ -234,14 +234,14 @@ static VOID
 }
 
 static VOID
-    PrintStackTrace(struct _EXCEPTION_POINTERS *ExceptionInfo)
+PrintStackTrace(struct _EXCEPTION_POINTERS *ExceptionInfo)
 {
     PVOID StartAddr;
     CHAR szMod[128] = "";
     PEXCEPTION_RECORD ExceptionRecord = ExceptionInfo->ExceptionRecord;
     PCONTEXT ContextRecord = ExceptionInfo->ContextRecord;
 
-    /* Print a stack trace. */
+    /* Print a stack trace */
     DbgPrint("Unhandled exception\n");
     DbgPrint("ExceptionCode:    %8x\n", ExceptionRecord->ExceptionCode);
 
@@ -310,12 +310,10 @@ static VOID
  */
 LONG
 NTAPI
-RtlUnhandledExceptionFilter(IN struct _EXCEPTION_POINTERS* ExceptionInfo)
+RtlUnhandledExceptionFilter(
+    _In_ PEXCEPTION_POINTERS ExceptionInfo)
 {
-    /* This is used by the security cookie checks, and also called externally */
-    UNIMPLEMENTED;
-    PrintStackTrace(ExceptionInfo);
-    return ERROR_CALL_NOT_IMPLEMENTED;
+    return RtlUnhandledExceptionFilter2(ExceptionInfo, "");
 }
 
 /*
@@ -325,12 +323,17 @@ LONG
 NTAPI
 RtlUnhandledExceptionFilter2(
     _In_ PEXCEPTION_POINTERS ExceptionInfo,
-    _In_ ULONG Flags)
+    _In_ PCSTR Function)
 {
     /* This is used by the security cookie checks, and also called externally */
     UNIMPLEMENTED;
+    ASSERT(ExceptionInfo && ExceptionInfo->ExceptionRecord);
+
     PrintStackTrace(ExceptionInfo);
-    return ERROR_CALL_NOT_IMPLEMENTED;
+
+    if (ExceptionInfo->ExceptionRecord->ExceptionCode == STATUS_POSSIBLE_DEADLOCK)
+        return EXCEPTION_CONTINUE_EXECUTION;
+    return EXCEPTION_CONTINUE_SEARCH;
 }
 
 /*