win: Save contents of TEBs allowing !teb and !gle to work in windbg

handler/win/crashy_test_program.cc

 // Copyright 2015 The Crashpad Authors. All rights reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#include "client/crashpad_client.h"
+#include <windows.h>
+#include <winternl.h>
+
+// ntstatus.h conflicts with windows.h so define this locally.
+#ifndef STATUS_NO_SUCH_FILE
+#define STATUS_NO_SUCH_FILE static_cast<NTSTATUS>(0xC000000F)
+#endif
 
 #include "base/logging.h"
+#include "client/crashpad_client.h"
 #include "tools/tool_support.h"
 
 namespace crashpad {
 namespace {
 
+ULONG RtlNtStatusToDosError(NTSTATUS status) {
+  static decltype(::RtlNtStatusToDosError)* rtl_nt_status_to_dos_error =
+      reinterpret_cast<decltype(::RtlNtStatusToDosError)*>(
+          GetProcAddress(LoadLibrary(L"ntdll.dll"), "RtlNtStatusToDosError"));
+  DCHECK(rtl_nt_status_to_dos_error);
+  return rtl_nt_status_to_dos_error(status);
+}
+
 void SomeCrashyFunction() {
+  // SetLastError and NTSTATUS so that we have something to view in !gle in
+  // windbg. RtlNtStatusToDosError() stores STATUS_NO_SUCH_FILE into the
+  // LastStatusError of the TEB as a side-effect, and we'll be setting
+  // ERROR_FILE_NOT_FOUND for GetLastError().
+  SetLastError(RtlNtStatusToDosError(STATUS_NO_SUCH_FILE));
   volatile int* foo = reinterpret_cast<volatile int*>(7);
   *foo = 42;
 }
 
 int CrashyMain(int argc, char* argv[]) {
   if (argc != 2) {
     fprintf(stderr, "Usage: %s <server_pipe_name>\n", argv[0]);
     return 1;
   }
 
@@ skipping 11 matching lines @@
 
   return 0;
 }
 
 }  // namespace
 }  // namespace crashpad
 
 int wmain(int argc, wchar_t* argv[]) {
   return crashpad::ToolSupport::Wmain(argc, argv, crashpad::CrashyMain);
 }