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 18 namespace base { 19 namespace 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. 26 typedef 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. 31 BASE_API WinProcExceptionFilter SetWinProcExceptionFilter( 32 WinProcExceptionFilter filter); 33 34 // Calls the registered exception filter. 35 BASE_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 // 55 template <WNDPROC proc> 56 LRESULT 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
