This file_write() function will give $filename the write permission before writing $content to it.

Note that many servers do not allow file permissions to be changed by the PHP user.

<?php
    function file_write($filename, &$content) { 
        if (!is_writable($filename)) {
            if (!chmod($filename, 0666)) {
                 echo "Cannot change the mode of file ($filename)";
                 exit;
            };
        }
        if (!$fp = @fopen($filename, "w")) {
            echo "Cannot open file ($filename)";
            exit;
        }
        if (fwrite($fp, $content) === FALSE) {
            echo "Cannot write to file ($filename)";
            exit;
        } 
        if (!fclose($fp)) {
            echo "Cannot close file ($filename)";
            exit;
        }
    } 
?>