The recode_file function will put the file position indicator at the end of each files, so if you want to re-use the handles use fseek beforehand.
(PHP 4, PHP 5)
recode_file — Recode from file to file according to recode request
Recode the file referenced by file handle input into the file referenced by file handle output according to the recode request.
Returns FALSE, if unable to comply, TRUE otherwise.
Example #1 Basic recode_file() example
$input = fopen('input.txt', 'r');
$output = fopen('output.txt', 'w');
recode_file("us..flat", $input, $output);
This function does not currently process file handles referencing remote files (URLs). Both file handles must refer to local files.