if err = forkExecPipe(p[:]); err != nil {
		releaseForkLock()
		return 0, err
	}

	// Kick off child.
	pid, err1 = forkAndExecInChild(argv0p, argvp, envvp, chroot, dir, attr, sys, p[1])
	if err1 != 0 {
		Close(p[0])
		Close(p[1])
		releaseForkLock()
		return 0, Errno(err1)
	}
	releaseForkLock()

	// Read child error status from pipe.
	Close(p[1])
	for {