title: Tamper system calls behavior with QEMU
body: <p>I don't know if this is the right place, but I don't know where I could ask.
  I'd like to change the system call behavior inside QEMU (or even inside the kernel if I can make this modification temporary), for instance if I call the read(fd) call, I would like to hook for this call and maybe change the file descriptor or the content itself.
  I would like to have a general structure like this, maybe by using a plugin or I don't know what:</p>
  <pre><code>syscall_interceptor(syscall, syscall_parameters){
      new_parameters = tamper(syscall_parameters)
      syscall(new_parameters )
  }
  </code></pre>
  <p>something like that. Is it possible? How?</p>