I'm trying to create a text file-based sequential url rotator by using the following code (original source):
<?php
$linksfile ="urlrotator.txt";
$posfile = "pos.txt";
$links = file($linksfile);
$numlinks = count($linksfile);
$fp = fopen($posfile, 'r+') or die("Failed to open posfile");
flock($fp, LOCK_EX);
$num = fread($fp, 1024);
if($num<$numlinks-1) {
fwrite($fp, $num+1);
} else {
fwrite($fp, 0);
}
flock($fp, LOCK_UN);
fclose($fp);
header("Location: {$links[$num]}");
?>
After my testing, I found that it keeps appending new position number as a string after the existing content of pos.txt and thus the script only works at the first time.
I tried adding the following line of code before the if else
statement in order to clear the existing content of pos.txt before updating it.
file_put_contents($posfile, "");
But then error ocurred at the line of redirection saying Undefined index: ......
.
Where could possibly go wrong?