funchook.nim

funchook wrapper for Nim

This wrapper compiles funchook with diStorm3 disassembler.

Suports both x64 and x86-64 on:

• Linux
• Windows
• MacOS (not tested yet)

Installation

nimble install funchook

Usage

import funchook

proc my_add(a, b: int): int =
  ## original proc to be hooked
  a + b

var add_func = my_add

proc hook_add(a, b: int): int =
  ## proc to replace my_add
  echo add_func(a, b) # call original proc with trampoline
  a * b

var h = initHook()

if h == nil:
  quit("Error: create funchook failed")

if h.prepare(addr add_func, hook_add) != SUCCESS:
  quit("Error: " & h.errorMessage())

assert my_add(4, 5) == 9, "pre-hook"

if h.install(0) != SUCCESS:
  quit("Error: " & h.errorMessage())

assert my_add(4, 5) == 20, "post-hook"