Google Interview Question (Implement unix tail using file API)

tail.php

<?php

function tail($filename, $numberOfLines){
	$counter = 0;
	$handler = fopen($filename, 'r');
	$end = filesize($filename);
	
	$start = -1;
	$current = $start;
	
	while($current+$end>0 && $counter<$numberOfLines){
		fseek($handler, $current, SEEK_END);
		$char = fread($handler, 1);
	
		while($char!=="\n" && $current+$end>=0){
			$here = $current+$end;
			fseek($handler, $current, SEEK_END);
			$char = fread($handler, 1);
			$current--;
		}
	
		if($current!=$start){
			if($end+$current+1!=0) {echo fread($handler, $end+$current+1)."\n";}
			else {
				fseek($handler, 0);
				echo fread($handler, $end+$start+1)."\n";
			}
			$start=$current;
			$counter++;
		}
	}
}


tail("lines.txt", 1);