1// Copyright (c) 2012 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 13#include <windows.h> 14 15#include "base/base_export.h" 16#include "base/strings/string16.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_EXPORT WinProcExceptionFilter SetWinProcExceptionFilter( 32 WinProcExceptionFilter filter); 33 34// Calls the registered exception filter. 35BASE_EXPORT int CallExceptionFilter(EXCEPTION_POINTERS* info); 36 37// Initializes the WNDCLASSEX structure |*class_out| to be passed to 38// RegisterClassEx() making sure that it is associated with the module 39// containing the window procedure. 40BASE_EXPORT void InitializeWindowClass( 41 const char16* class_name, 42 WNDPROC window_proc, 43 UINT style, 44 int class_extra, 45 int window_extra, 46 HCURSOR cursor, 47 HBRUSH background, 48 const char16* menu_name, 49 HICON large_icon, 50 HICON small_icon, 51 WNDCLASSEX* class_out); 52 53// Wrapper that supplies a standard exception frame for the provided WindowProc. 54// The normal usage is something like this: 55// 56// LRESULT CALLBACK MyWinProc(HWND hwnd, UINT message, 57// WPARAM wparam, LPARAM lparam) { 58// // Do Something. 59// } 60// 61// ... 62// 63// WNDCLASSEX wc = {0}; 64// wc.lpfnWndProc = WrappedWindowProc<MyWinProc>; 65// wc.lpszClassName = class_name; 66// ... 67// RegisterClassEx(&wc); 68// 69// CreateWindowW(class_name, window_name, ... 70// 71template <WNDPROC proc> 72LRESULT CALLBACK WrappedWindowProc(HWND hwnd, UINT message, 73 WPARAM wparam, LPARAM lparam) { 74 LRESULT rv = 0; 75 __try { 76 rv = proc(hwnd, message, wparam, lparam); 77 } __except(CallExceptionFilter(GetExceptionInformation())) { 78 } 79 return rv; 80} 81 82} // namespace win 83} // namespace base 84 85#endif // BASE_WIN_WRAPPED_WINDOW_PROC_H_ 86