// duplicate signal in rare cases, but it won't matter when
		// using SIGKILL.
		r1, _, _ = RawSyscall(SYS_GETPPID, 0, 0, 0)
		if r1 != ppid {
			upid, _, _ = RawSyscall(SYS_GETPID, 0, 0, 0)
			_, _, err1 = RawSyscall(SYS_KILL, upid, uintptr(sys.Pdeathsig), 0)
			if err1 != 0 {
				goto childerror
			}
		}
	}

	// Pass 1: look for fd[i] < i and move those up above len(fd)
	// so that pass 2 won't stomp on an fd it needs later.