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
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 using WinProcExceptionFilter = int (CDECL *)(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_EXPORT WinProcExceptionFilter
32 SetWinProcExceptionFilter(WinProcExceptionFilter filter);
33
34 // Calls the registered exception filter.
35 BASE_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.
40 BASE_EXPORT void InitializeWindowClass(const char16* class_name,
41 WNDPROC window_proc,
42 UINT style,
43 int class_extra,
44 int window_extra,
45 HCURSOR cursor,
46 HBRUSH background,
47 const char16* menu_name,
48 HICON large_icon,
49 HICON small_icon,
50 WNDCLASSEX* class_out);
51
52 // Wrapper that supplies a standard exception frame for the provided WindowProc.
53 // The normal usage is something like this:
54 //
55 // LRESULT CALLBACK MyWinProc(HWND hwnd, UINT message,
56 // WPARAM wparam, LPARAM lparam) {
57 // // Do Something.
58 // }
59 //
60 // ...
61 //
62 // WNDCLASSEX wc = {0};
63 // wc.lpfnWndProc = WrappedWindowProc<MyWinProc>;
64 // wc.lpszClassName = class_name;
65 // ...
66 // RegisterClassEx(&wc);
67 //
68 // CreateWindowW(class_name, window_name, ...
69 //
70 template <WNDPROC proc>
71 LRESULT CALLBACK
WrappedWindowProc(HWND hwnd,UINT message,WPARAM wparam,LPARAM lparam)72 WrappedWindowProc(HWND hwnd, UINT message, WPARAM wparam, LPARAM lparam) {
73 LRESULT rv = 0;
74 __try {
75 rv = proc(hwnd, message, wparam, lparam);
76 } __except (CallExceptionFilter(GetExceptionInformation())) {
77 }
78 return rv;
79 }
80
81 } // namespace win
82 } // namespace base
83
84 #endif // BASE_WIN_WRAPPED_WINDOW_PROC_H_
85