Function foreach

src/posix/subprocess.hpp:127–132

          fd != STDERR_FILENO) {
        bool found = false;
        foreach (int_fd whitelist_fd, whitelist_fds) {
          if (whitelist_fd == fd) {
            found = true;
            break;
          }
        }

        if (!found) {
          int flags = ::fcntl(fd, F_GETFD);