Function fork_process

kernel/oswrapper/vspace.cc:426–454

} // namespace internals

pid_t fork_process() {
  using namespace internals;
  lock_metapage();
  for (int p = 0; p < MAX_PROCESS; p++) {
    if (vmem.metapage->process_info[p].pid == 0) {
      pid_t pid = fork();
      if (pid < 0) {
        // error
        return -1;
      } else if (pid == 0) {
        // child process
        int parent = vmem.current_process;
        vmem.current_process = p;
        lock_metapage();
        vmem.metapage->process_info[p].pid = getpid();
        unlock_metapage();
        send_signal(parent);
      } else {
        // parent process
        unlock_metapage();
        wait_signal();
        // child has unlocked metapage, so we don't need to.
      }
      return pid;
    }
  }
  unlock_metapage();
  return -1;
}

void Semaphore::post() {
  int wakeup = -1;