This library provides a type-safe and thread-safe way to inline hook API or functions. The following example shows how to hook a windows API with a hand written API that calls the origin one.
int __stdcall MyMessageBoxA(HWND hWnd, LPCSTR lpText, LPCSTR lpCaption, UINT uType) { lpText = "hooked text"; return hookapi::call_origin(MessageBoxA)(hWnd, lpText, lpCaption, uType); }
int main() { hookapi::hook(MessageBoxA, MyMessageBoxA); MessageBoxA(nullptr, "text", "caption", MB_OK); return 0; }
The hookapi::hook verifies the shell API has the same signature as the hooked API, if not the same, a compile time error will exert. There is another type-unsafe method which allows users to hook a code address.
hookapi::hook_unsafe((PVOID)0x1000E7F0, MyFunction);
There are two ways to call the original API. First of call, if you call the MessageBoxA inside MyMessageBoxA, it leads to a permenant recursion and eventually crashs. If the API has exported symbol, call_origin method is preferred.
hookapi::call_origin(MessageBoxA)(hWnd, lpText, lpCaption, uType);
or assume that you don't know the origin API, it is hooked by address, then use call_origin_by_hook.
hookapi::call_origin_by_hook(MyMessageBoxA)(hWnd, lpText, lpCaption, uType);
To unhook the API, call
hookapi::unhook(MessageBoxA);
There are some problems with hooking x64 functions. Some instructions using indirect addressing mode in x64 refer memory by offset, while in x86 refer by absolute address. The difference cause the execution result of these instructions depends on the address of them. I will find out some way to resolve this problem gracefully.