為open source community盡棉薄之力 -- pyHook篇

最近嚐試著使用python寫一個keylogger，編寫的過程中使用到UNC放出來的pyHook模組，pyHook提供Windows用戶把一些低階的keyboard & mouse hook功能。當我在try的時候發現除了ALT以外的每個按鍵都可以被正常擷取，唯有ALT鍵每按兩次就會跳出一個runtime warning，訊息如下：

C:\work\code\code_python\svn\nws\keylogger>python keylogger.py
Lmenu
C:\Python25\lib\site-packages\pyHook\HookManager.py:353: RuntimeWarning: tp_comp
are didn't return -1 or -2 for exception
func = self.keyboard_funcs.get(msg)
Traceback (most recent call last):
File "C:\Python25\lib\site-packages\pyHook\HookManager.py", line 353, in Keybo
ardSwitch
func = self.keyboard_funcs.get(msg)
TypeError: an integer is required
Lmenu
Traceback (most recent call last):
File "C:\Python25\lib\site-packages\pyHook\HookManager.py", line 353, in Keybo
ardSwitch
func = self.keyboard_funcs.get(msg)
TypeError: an integer is required

當我trace進HookManager.py之後發現一件相當有趣的問題，那就是msg本身就已經是integer類別，不知道為何還會產生上面的警告訊息，於是我乾脆一不做二不休，將code由

    func = self.keyboard_funcs.get(msg)

改為（ALT鍵屬於WM_SYSKEYDOWN）

    if msg == HookConstants.WM_SYSKEYDOWN:
        func = self.keyboard_funcs.get(HookConstants.WM_SYSKEYDOWN)
    else:
        func = self.keyboard_funcs.get(msg)

沒想到問題就這麼迎刃而解！

C:\work\code\code_python\svn\nws\keylogger>python keylogger.py
Lmenu
Lmenu
Rmenu
Lmenu
Lmenu
Lmenu
Lmenu
Lmenu
Lmenu
Lmenu
Lmenu
Lmenu

隨後已寫信給作者反應此問題，如此也算是替open source community盡了點心力。