}
	if sys.Setctty && sys.Ctty >= len(attr.Files) {
		return 0, errorspkg.New("Setctty set but Ctty not valid in child")
	}

	acquireForkLock()

	// Allocate child status pipe close on exec.
	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])

	}
	nextfd++

	// Allocate another pipe for parent to child communication for
	// synchronizing writing of User ID/Group ID mappings.
	if sys.UidMappings != nil || sys.GidMappings != nil {
		if err := forkExecPipe(mapPipe[:]); err != nil {
			err1 = err.(Errno)
			return
		}
	}

	flags = sys.Cloneflags
	if sys.Cloneflags&CLONE_NEWUSER == 0 && sys.Unshareflags&CLONE_NEWUSER == 0 {
		flags |= CLONE_VFORK | CLONE_VM