1// Copyright (c) 2011 The Chromium Authors. All rights reserved. 2// Use of this source code is governed by a BSD-style license that can be 3// found in the LICENSE file. 4 5// Provides a way to handle exceptions that happen while a WindowProc is 6// running. The behavior of exceptions generated inside a WindowProc is OS 7// dependent, but it is possible that the OS just ignores the exception and 8// continues execution, which leads to unpredictable behavior for Chrome. 9 10#ifndef BASE_WIN_WRAPPED_WINDOW_PROC_H_ 11#define BASE_WIN_WRAPPED_WINDOW_PROC_H_ 12#pragma once 13 14#include <windows.h> 15 16#include "base/base_api.h" 17 18namespace base { 19namespace win { 20 21// An exception filter for a WindowProc. The return value determines how the 22// exception should be handled, following standard SEH rules. However, the 23// expected behavior for this function is to not return, instead of returning 24// EXCEPTION_EXECUTE_HANDLER or similar, given that in general we are not 25// prepared to handle exceptions. 26typedef int (__cdecl *WinProcExceptionFilter)(EXCEPTION_POINTERS* info); 27 28// Sets the filter to deal with exceptions inside a WindowProc. Returns the old 29// exception filter, if any. 30// This function should be called before any window is created. 31BASE_API WinProcExceptionFilter SetWinProcExceptionFilter( 32 WinProcExceptionFilter filter); 33 34// Calls the registered exception filter. 35BASE_API int CallExceptionFilter(EXCEPTION_POINTERS* info); 36 37// Wrapper that supplies a standard exception frame for the provided WindowProc. 38// The normal usage is something like this: 39// 40// LRESULT CALLBACK MyWinProc(HWND hwnd, UINT message, 41// WPARAM wparam, LPARAM lparam) { 42// // Do Something. 43// } 44// 45// ... 46// 47// WNDCLASSEX wc = {0}; 48// wc.lpfnWndProc = WrappedWindowProc<MyWinProc>; 49// wc.lpszClassName = class_name; 50// ... 51// RegisterClassEx(&wc); 52// 53// CreateWindowW(class_name, window_name, ... 54// 55template <WNDPROC proc> 56LRESULT CALLBACK WrappedWindowProc(HWND hwnd, UINT message, 57 WPARAM wparam, LPARAM lparam) { 58 LRESULT rv = 0; 59 __try { 60 rv = proc(hwnd, message, wparam, lparam); 61 } __except(CallExceptionFilter(GetExceptionInformation())) { 62 } 63 return rv; 64} 65 66} // namespace win 67} // namespace base 68 69#endif // BASE_WIN_WRAPPED_WINDOW_PROC_H_ 70