http byte range file server

gistfile1.aw

<?php
// check if the file actually exists.
if (file_exists($filePath)) {
    //everything OK, log the access and start pushing the file.
    $info = pathinfo($filePath);
    $fileSize = filesize($filePath) - 1;
    $fp = fopen($filePath, 'rb');
    
    // push it.
    header("Expires: 0");
    header('Content-Type: ' . $this->extensionToMime($info['extension']));
    header("Cache-Control: no-store, no-cache, must-revalidate, post-check=0, pre-check=0");
    header("Pragma: no-cache");
    header("Accept-Ranges: 0-$fileSize");
    header("Content-Length: " . $fileSize);
    if ($this->dispositionHeader) {
        header('Content-Disposition: attachment; filename="' . $info['basename'] . '"');
    }
    $start = 0; // Start byte
    $end = $fileSize; // End byte
    //get the HTTP_RANGE Header (required for iPad/HTML5 pseudostreaming)
    $range = $request->getServer('HTTP_RANGE');
    // was the RANGE header actually set?
    if ($range != NULL) {
        $range = explode('=', $range);
        // should be exactly 2 keys, and the request MUST be addressing by bytes.
        if (count($range) == 2 && $range[0] == 'bytes') {
            // now try to extract the start/end offsets.
            $boundaries = explode('-', $range[1]);
            // empty start defaults to 0 which is file_start.
            $start = intval($boundaries[0]);
            $end = intval($boundaries[1]);
            // if end is empty, just push until file_end.
            if ($end == 0) {
                $end = $fileSize;
            }
            if ($end < $start || $end > $fileSize) {
                header("Status: 416 Requested range not satisfiable");
                header("Content-Range: */$fileSize");
                return;
            }
            fseek($fp, $start);
            header('HTTP/1.1 206 Partial Content');
            // Notify the client the byte range we'll be outputting
            header("Content-Range: bytes $start-$end/$fileSize");
        }
    } elseif ($request->getParam('start') != null) {
        $start = intval(str_replace('.', '', $request->getParam('start', 0)));
        if ($start < $end) {
            fseek($fp, $start);
        } else {
            header("Status: 416 Requested range not satisfiable");
            return;
        }
    }
    
    $currPos = $start;
    // now push the requested file section to the client.
    while (! feof($fp) && $currPos < $end) {
        /**
         * Chunks are the sections read from the file at once.
         * This significantly reduces memory usage, since only one chunk resides 
         * in memory at one time. Choosing a small chunk size increases the php overhead though.
         */
        $chunk = 16 * 1024;
        $currPos = ftell($fp);
        // check if we would overshoot the requested byterange of we push the whole chunk.
        if (($currPos + $chunk) > $end) {
            //adjust the chunk size
            $chunk = $end - $currPos;
            // umm.. are we in the badlands already?
            if ($chunk <= 0) {
                break;
            }
        }
        echo (fread($fp, $chunk));
        ob_flush();
    }
    fclose($fp);
    return;
}