(no version information, might be only in CVS)
php_stream_copy_to_stream()
attempts to read up to
maxlen bytes of data from
src and write them to
dest, and returns the number of bytes that were
successfully copied.
If you want to copy all remaining data from the src stream, pass the constant
PHP_STREAM_COPY_ALL as the
value of maxlen.
注: This function will attempt to copy the data in the most efficient manner, using memory mapped files when possible.