hook.h

#pragma once
#include <stdio.h>

/**
 * Opaque type containing hook metadata. Use it to revert hooks.
 */
typedef void* hook_t;

/**
 * Install a hook that works by JMP-ing to the new implementation.
 * This is handy for hooking existing functions, override their first bytes by a
 * JMP and all the arguments will still be on the stack/in registries. C
 * functions can just be used (with appropriate calling convention) as if they
 * were called directly by the application.
 */
hook_t install_jmphook(void* orig_address, void* hook_address);

/**
 * Install a hook that works by CALL-ing to the new implementation.
 * Handy for hooking existing CALL-sites, overriding essentially just the
 * address.
 */
hook_t install_callhook(void* orig_address, void* hook_address);

/**
 * Install a hook that works by overriding a pointer in a vtable.
 * Handy for hooking class methods.
 */
hook_t install_vtblhook(void* orig_address, void* hook_address);

/**
 * Overwrite some arbitrary bytes, not necessarily a call/jmp/vtbl hook.
 */
hook_t install_bytes(void* orig_address, void* buffer, size_t buf_size);

/**
 * Revert an existing hook.
 */
void revert_hook(hook_t hook);