<?php

// Source: http://ibnuyahya.com/format-bytes-to-kb-mb-gb/
function format_bytes($size, $precision = 2){
		$base = log($size) / log(1024);
		$suffixes = array('B', 'KiB', 'MiB', 'GiB', 'TiB' , 'PiB' , 'EiB');
		return round(pow(1024, $base - floor($base)), $precision) . $suffixes[floor($base)];
}

// Original source: http://www.phpfreaks.com/forums/index.php?topic=198274.msg895468#msg895468
function rangeDownload($file, $filename, $type)
{
	$fp = @fopen($file, 'r');

	$size	= filesize($file); // File size
	$length = $size;	   // Content length
	$start	= 0;		   // Start byte
	$end	= $size - 1;	   // End byte
	// Now that we've gotten so far without errors we send the accept range header
	/* At the moment we only support single ranges.
	 * Multiple ranges requires some more work to ensure it works correctly
	 * and comply with the spesifications: http://www.w3.org/Protocols/rfc2616/rfc2616-sec19.html#sec19.2
	 *
	 * Multirange support annouces itself with:
	 * header('Accept-Ranges: bytes');
	 *
	 * Multirange content must be sent with multipart/byteranges mediatype,
	 * (mediatype = mimetype)
	 * as well as a boundry header to indicate the various chunks of data.
	 */
	header("Accept-Ranges: 0-$length");
	// header('Accept-Ranges: bytes');
	// multipart/byteranges
	// http://www.w3.org/Protocols/rfc2616/rfc2616-sec19.html#sec19.2
	if (isset($_SERVER['HTTP_RANGE']))
	{
		$c_start = $start;
		$c_end	 = $end;
		// Extract the range string
		list(, $range) = explode('=', $_SERVER['HTTP_RANGE'], 2);
		// Make sure the client hasn't sent us a multibyte range
		if (strpos($range, ',') !== false)
		{
			// (?) Shoud this be issued here, or should the first
			// range be used? Or should the header be ignored and
			// we output the whole content?
			header('HTTP/1.1 416 Requested Range Not Satisfiable');
			header("Content-Range: bytes $start-$end/$size");
			// (?) Echo some info to the client?
			exit;
		}
		// If the range starts with an '-' we start from the beginning
		// If not, we forward the file pointer
		// And make sure to get the end byte if spesified
		if ($range{0} == '-')
		{
			// The n-number of the last bytes is requested
			$c_start = $size - substr($range, 1);
		}
		else
		{
			$range	= explode('-', $range);
			$c_start = $range[0];
			$c_end	 = (isset($range[1]) && is_numeric($range[1])) ? $range[1] : $size;
		}
		/* Check the range and make sure it's treated according to the specs.
		 * http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html
		 */
		// End bytes can not be larger than $end.
		$c_end = ($c_end > $end) ? $end : $c_end;
		// Validate the requested range and return an error if it's not correct.
		if ($c_start > $c_end || $c_start > $size - 1 || $c_end >= $size)
		{
			header('HTTP/1.1 416 Requested Range Not Satisfiable');
			header("Content-Range: bytes $start-$end/$size");
			// (?) Echo some info to the client?
			exit;
		}
		$start	= $c_start;
		$end	= $c_end;
		$length = $end - $start + 1; // Calculate new content length
		fseek($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/$size");
	header("Content-Length: $length");
	header("Content-disposition: inline; filename=\"".$filename."\"\n");
	header("Content-Type: ".$type."\n");

	// Start buffered download
	$buffer = 1024 * 8;
	while(!feof($fp) && ($p = ftell($fp)) <= $end)
	{
		if ($p + $buffer > $end)
		{
			// In case we're only outputtin a chunk, make sure we don't
			// read past the length
			$buffer = $end - $p + 1;
		}
		set_time_limit(0); // Reset time limit for big files
		echo fread($fp, $buffer);
		flush(); // Free up memory. Otherwise large files will trigger PHP's memory limit.
	}

	fclose($fp);
}

function even_odd($reset = false)
{
	static $counter = 1;

	if ($reset) {
		$counter = 1;
	}

	if ($counter++%2 == 0) {
		return 'even';
	} else {
		return 'odd';
	}
}

// Source: http://hu.php.net/manual/en/function.str-pad.php#71558
// This is a multibyte enabled str_pad
function mb_str_pad($ps_input, $pn_pad_length, $ps_pad_string = " ", $pn_pad_type = STR_PAD_RIGHT, $ps_encoding = NULL)
{
	$ret = "";

	if (is_null($ps_encoding))
		$ps_encoding = mb_internal_encoding();

	$hn_length_of_padding = $pn_pad_length - mb_strlen($ps_input, $ps_encoding);
	$hn_psLength = mb_strlen($ps_pad_string, $ps_encoding); // pad string length

	if ($hn_psLength <= 0 || $hn_length_of_padding <= 0) {
		// Padding string equal to 0:
		//
		$ret = $ps_input;
		}
	else {
		$hn_repeatCount = floor($hn_length_of_padding / $hn_psLength); // how many times repeat

		if ($pn_pad_type == STR_PAD_BOTH) {
			$hs_lastStrLeft = "";
			$hs_lastStrRight = "";
			$hn_repeatCountLeft = $hn_repeatCountRight = ($hn_repeatCount - $hn_repeatCount % 2) / 2;

			$hs_lastStrLength = $hn_length_of_padding - 2 * $hn_repeatCountLeft * $hn_psLength; // the rest length to pad
			$hs_lastStrLeftLength = $hs_lastStrRightLength = floor($hs_lastStrLength / 2);			// the rest length divide to 2 parts
			$hs_lastStrRightLength += $hs_lastStrLength % 2; // the last char add to right side

			$hs_lastStrLeft = mb_substr($ps_pad_string, 0, $hs_lastStrLeftLength, $ps_encoding);
			$hs_lastStrRight = mb_substr($ps_pad_string, 0, $hs_lastStrRightLength, $ps_encoding);

			$ret = str_repeat($ps_pad_string, $hn_repeatCountLeft) . $hs_lastStrLeft;
			$ret .= $ps_input;
			$ret .= str_repeat($ps_pad_string, $hn_repeatCountRight) . $hs_lastStrRight;
			}
		else {
			$hs_lastStr = mb_substr($ps_pad_string, 0, $hn_length_of_padding % $hn_psLength, $ps_encoding); // last part of pad string

			if ($pn_pad_type == STR_PAD_LEFT)
				$ret = str_repeat($ps_pad_string, $hn_repeatCount) . $hs_lastStr . $ps_input;
			else
				$ret = $ps_input . str_repeat($ps_pad_string, $hn_repeatCount) . $hs_lastStr;
			}
		}

	return $ret;
}

function is_cli_client()
{
	// official client uses "fb-client/$version" as useragent
	$clients = array("fb-client", "libcurl", "pyfb");
	foreach ($clients as $client) {
		if (isset($_SERVER['HTTP_USER_AGENT']) && strpos($_SERVER['HTTP_USER_AGENT'], $client) !== false) {
			return true;
		}
	}
	return false;
}

function random_id($min_length, $max_length)
{
	$random = '';
	$char_list = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
	$char_list .= "abcdefghijklmnopqrstuvwxyz";
	$char_list .= "1234567890";
	$length = rand()%($max_length-$min_length) + $min_length;

	for($i = 0; $i < $max_length; $i++) {
		if (strlen($random) == $length) break;
		$random .= substr($char_list,(rand()%(strlen($char_list))), 1);
	}
	return $random;
}

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