if !raceenabled {
		return
	}
	for i := 0; n > 0 && i < len(iovecs); i++ {
		m := int(iovecs[i].Len)
		if m > n {
			m = n
		}
		n -= m
		if m > 0 {
			raceReadRange(unsafe.Pointer(iovecs[i].Base), m)
		}
	}
}

// mmap varies by architecture; see syscall_linux_*.go.
//sys	munmap(addr uintptr, length uintptr) (err error)

	if raceenabled {
		raceReleaseMerge(unsafe.Pointer(&ioSync))
	}
	err := writeFile(fd, p, done, overlapped)
	if raceenabled && *done > 0 {
		raceReadRange(unsafe.Pointer(&p[0]), int(*done))
	}
	return err
}

var ioSync int64

func Seek(fd Handle, offset int64, whence int) (newoffset int64, err error) {
	var w uint32
	switch whence {
	case 0:

	}
	return
}

func Write(fd int, p []byte) (n int, err error) {
	if raceenabled {
		raceReleaseMerge(unsafe.Pointer(&ioSync))
	}
	n, err = write(fd, p)
	if raceenabled && n > 0 {
		raceReadRange(unsafe.Pointer(&p[0]), n)
	}
	return
}

// For testing: clients can set this flag to force
// creation of IPv6 sockets to return EAFNOSUPPORT.
var SocketDisableIPv6 bool