shithook/main.cpp

#include <iostream>
#include "hook.hpp"
using namespace std;

BOOL HookWriteFile(
    HANDLE       hFile,
    LPCVOID      lpBuffer,
    DWORD        nNumberOfBytesToWrite,
    LPDWORD      lpNumberOfBytesWritten,
    LPOVERLAPPED lpOverlapped
)
{
    //this will change the output to "shithooked!\n"
    const char* shithooked = "shithooked!?";
    hook::disable(&WriteFile);
    BOOL result = WriteFile(
        hFile,
        shithooked,
        nNumberOfBytesToWrite,
        lpNumberOfBytesWritten, 
        lpOverlapped
    );
    hook::enable(&WriteFile);
    return result;
}

int main()
{
    //make hook
    hook::make_hook(
        &WriteFile,
        &HookWriteFile,
        false // you can choose not to install it yet
    );

    //make file
    OFSTRUCT ofstruct{};
    auto result = std::unique_ptr<std::remove_pointer_t<HANDLE>, decltype(&CloseHandle)>(
        (HANDLE)(OpenFile(
            "output.txt",
            &ofstruct,
            OF_READWRITE | OF_CREATE
        )), &CloseHandle
    );

    if (reinterpret_cast<HFILE>(result.get()) != HFILE_ERROR)
    {
        // we can enable it after we open the file
        hook::enable(&WriteFile);

        //write to file
        const char aString[] = "Hello world!\n";
        WriteFile(result.get(), aString, sizeof(aString), NULL, NULL);
    }
}