(PHP 4 >= 4.2.0, PHP 5 <= 5.0.4)
Truncates file descriptor fd to offset bytes
( resource fd, int offset )
dio_truncate() truncates a file to at most
offset bytes in size.
If the file previously was larger than this size, the extra data is
lost. If the file previously was shorter, it is unspecified whether the
file is left unchanged or is extended. In the latter case the extended
part reads as zero bytes.
Замечание: Для Windows-платформ
эта функция не реализована.