errno = save_errno;
static void sigchld_handler(int signum){    pid_t pid;    int status;    pid = waitpid(-1, &status, WNOHANG);    if (pid == pty_child_pid && (WIFEXITED(status) || WIFSIGNALED(status))) {	pty_exit_code = status;	pty_child_dead = TRUE;    }}