问题描述
下面的代码位于我用来挂钩 CreateWindowExA() 和其他函数的 DLL 中.
The code below is inside of a DLL that I'm using to hook CreateWindowExA() and other functions.
当我使用 std::wstringstream 将变量的值打印到 DebugView.我确认当我评论 std::wstringstream 时它不会崩溃.
The current hooked app is crashing when I use std::wstringstream to print the values of the variables to DebugView. I confirmed that when I comment the std::wstringstream it doesn't crash.
我还可以使用哪些其他选项来打印它们的值，而无需指定每个变量类型，就像您在 wsprintf() 上所做的那样?
What other option can I use to print their values that I don't need to specify each variable type, as you do on wsprintf()?
HWND __stdcall CreateWindowExA_Hook(
DWORD dwExStyle,
LPCSTR lpClassName,
LPCSTR lpWindowName,
DWORD dwStyle,
int X,
int Y,
int nWidth,
int nHeight,
HWND hWndParent,
HMENU hMenu,
HINSTANCE hInstance,
LPVOID lpParam
)
{
std::wstringstream text;
text << L"dwExStyle: " << dwExStyle << L" lpClassName: " << lpClassName << L" lpWindowName: " << lpWindowName
<< L" dwStyle: " << dwStyle << L" X: " << X << L" Y: " << Y << L" nWidth: " << nWidth << L" nHeight: " << nHeight
<< L" hWndParent: " << hWndParent << L" hMenu" << hMenu << L" hInstance: " << hInstance << L" lpParam: " << lpParam;
OutputDebugString(L"CreateWindowExA:");
OutputDebugString(text.str().c_str());
OutputDebugString(L" ");
return CreateWindowExA(dwExStyle, lpClassName, lpWindowName, dwStyle, X, Y, nWidth, nHeight, hWndParent, hMenu, hInstance, lpParam);
}
我想知道是否有比这样做更好"的方法:
I wonder if there's any 'better' way than doing this:
std::wstringstream ss;
( dwExStyle ? ss << L"dwExStyle: " << dwExStyle : ss << 0 );
( lpClassName ? ss << L" lpClassName: " << lpClassName : ss << 0 );
( lpWindowName ? ss << L" lpWindowName: " << lpWindowName : ss << 0 );
( dwStyle ? ss << L" dwStyle: " << dwStyle : ss << 0 );
....
OutputDebugString(L"CreateWindowExA:");
OutputDebugString(text.str().c_str());
OutputDebugString(L" ");
推荐答案
使用 wstringstream 打印非字符串 NULL 指针没有问题，它们按原样打印作为数值(即，0x00000000).只有 NULL 字符串指针可能有问题，并且此代码中唯一的字符串指针是 lpClassName 和 lpWindowName，因此只需检查它们的 NULL 显式，例如:
There is no problem printing non-string NULL pointers with wstringstream, they are printed as-is as numeric values (ie, 0x00000000). Only NULL string pointers could be a problem, and the only string pointers in this code are lpClassName and lpWindowName, so just check them for NULL explicitly, eg:
std::wstringstream text;
text << ...
<< L" lpClassName: " << (lpClassName ? lpClassName : L"")
<< L" lpWindowName: " << (lpWindowName ? lpWindowName : L"")
<< ...;
您不需要将 ?: 用于其他参数值，因为当 0/NULL.
You don't need to use ?: for the other parameter values, as they are perfectly safe to print as-is when 0/NULL.
附带说明一下，我还建议在钩子内尽可能少地调用 OutputDebugString()，因此您应该包含您的 L"CreateWindowExA:"wstringstream 文本中的前缀.
On a side note, I would also suggest calling OutputDebugString() as few times as possible inside a hook, so you should include your L"CreateWindowExA:" prefix in your wstringstream text.
试试这个:
HWND __stdcall CreateWindowExA_Hook(
DWORD dwExStyle,
LPCSTR lpClassName,
LPCSTR lpWindowName,
DWORD dwStyle,
int X,
int Y,
int nWidth,
int nHeight,
HWND hWndParent,
HMENU hMenu,
HINSTANCE hInstance,
LPVOID lpParam
)
{
std::wstringstream text;
text << L"CreateWindowExA:"
<< L" dwExStyle: " << dwExStyle
<< L" lpClassName: " << (!lpClassName ? lpClassName : L"")
<< L" lpWindowName: " << (!lpWindowName ? lpWindowName : L"")
<< L" dwStyle: " << dwStyle
<< L" X: " << X
<< L" Y: " << Y
<< L" nWidth: " << nWidth
<< L" nHeight: " << nHeight
<< L" hWndParent: " << hWndParent
<< L" hMenu" << hMenu
<< L" hInstance: " << hInstance
<< L" lpParam: " << lpParam
<< L"\n \n";
OutputDebugStringW(text.str().c_str());
return CreateWindowExA(dwExStyle, lpClassName, lpWindowName, dwStyle, X, Y, nWidth, nHeight, hWndParent, hMenu, hInstance, lpParam);
}
更新:根据 Easyhook 的文档:
UPDATE: per Easyhook's documentation:
注意:EasyHook 以这样一种方式实现钩子蹦床代码，即在钩子处理程序中直接(或间接)调用原始方法将绕过钩子处理程序并调用原始方法.
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