I made a PHP script to auto manage download locations for multiple servers

PHP Code:
<?php
$CACHE_FILE="/home/evilkittie/.xonotic/urlcache.serial";// create this file and be make sure www-data has write access (you can place this in /var/cache if you prefer)
$data="/home/evilkittie/.xonotic/data";// Path to Xonotic's data folder
$servers=(object)array(// Game server is used as last resort (pay attention to commas at the end of lines in here)
   // true means use a HTTPS connection
   // false means use a HTTP connection
   "dl.xonotic.co"=>false,
   "xonotic.devfull.de/packages"=>true
);
function checkRemoteFile($path,$file,$https){
   // based on answer here
   // https://stackoverflow.com/questions/1363925/check-whether-image-exists-on-remote-url
   $cache=(object)$GLOBALS["cache"];
   if(isset($cache->{$path}) && isset($cache->{$path}->{$file})){// Is this cached?
      return $cache->{$path}->{$file};// looks like it
   }
   else{// not cached, lets cache it!
      /* Caching method is not perfect, there is a chance we could 
       * delete a small amount of cache doing this (no file lock)
       * however it is only a cache we will get it sooner or later.
       */ 
      $ch=curl_init();
      curl_setopt($ch, CURLOPT_URL,"http".($https?'s':'')."://$path/$file");
      // don't download content
      curl_setopt($ch, CURLOPT_NOBODY, 1);
      curl_setopt($ch, CURLOPT_FAILONERROR, 1);
      curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
      $result=curl_exec($ch)!==FALSE;
      curl_close($ch);
      if($GLOBALS["cacheTime"]!=filemtime($GLOBALS["CACHE_FILE"]))// did the cache change on us?
         $cache=loadCache();// refresh it
      if(!isset($cache->{$path}))
         $cache->{$path}=(object)array();
      $cache->{$path}->{$file}=$result;
      saveCache($cache);
      $GLOBALS["cache"]=$cache;//export cache
      return $cache->{$path}->{$file};// is the file there?
   }
}
function loadCache(){
   $CACHE_FILE=$GLOBALS["CACHE_FILE"];
   $cache=file_get_contents($CACHE_FILE);
   if(filesize($CACHE_FILE)==0)// Assume file exist (*points at line 2*)
      $cache=(object)array();
   else{
      $cache=false;
      $ct=0;// safety
      while($cache===false){
         if($cache===false){// did it work?
            if($ct!==0)
               usleep(10000);// wait 0.01 seconds
            $cache=file_get_contents($CACHE_FILE);// must have opened while data was being written
         }
         $cache=@unserialize($cache);// vastly faster than json_parse
         $ct++;
         if($ct>100){
            // cache appears to be broken
            $cache=(object)array();
            break;
         }
      }
      $GLOBALS["cacheTime"]=filemtime($CACHE_FILE);
   }
   return $cache;
}
function saveCache($cache){
   $f=fopen($GLOBALS["CACHE_FILE"],"w");// open cache
   fwrite($f, serialize($cache));//write cache
   fclose($f);//save cache
}
if(isset($argv)){// cli management
   foreach($argv as $key => $val){
      if($val=="--dump"){
         var_dump(unserialize(file_get_contents($CACHE_FILE)));
      }
      if($val=="--truncate"){
         file_put_contents($CACHE_FILE, "");
      }
      if($val=="--delete"){
         if(!isset($argv[$key+1]))
            echo "--delete requires a file name";
         else{
            $del=$argv[$key+1];
            $cache=loadCache();
            foreach($cache as $s => $f){
               if(isset($cache->{$s}->{$del}))
                  unset($cache->{$s}->{$del});
            }
            saveCache($cache);
         }
      }
      if($val=="--drop"){
         if(!isset($argv[$key+1]))
            echo "--drop requires a path name";
         else{
            $del=$argv[$key+1];
            $cache=loadCache();
            if(isset($cache->{$del}))
               unset($cache->{$del});
            saveCache($cache);
         }
      }
      if($val=="--help"){
         echo "Options:\n\t".
            "--dump\n\t\tDump cache in a readable format\n\t".
            "--truncate\n\t\tDelete cache file content\n\t".
            "--delete\n\t\tDelete a file from cache\n\t".
            "--drop\n\t\tRemove a entire server's folder from cache\n\t".
            "--help\n\t\tShow this help info";
      }
   }
   die("\n");
}
if(!isset($_GET['file']))
   die("file parameter is required!");
$file=$_GET['file'];
$file=substr($file,strrpos($file,'/'));// SECURITY MEASURE: DO NOT DELETE!
$cache=loadCache();
foreach($servers as $key => $val){
   if(checkRemoteFile($key,$file,$val))
      exit(header("Location: http".($val?'s':'')."://$key/$file"));
}
if(file_exists("$data/$file")){// guess we better send them our local copy
   if(strtolower(substr(strrpos($file,".")))!='.pk3'){// are you trying to get server.cfg?
      header('HTTP/1.0 403 Forbidden');// denied
      header("Content-Type: text/plain");
      die("Where did you get that file name anyway?");
  }
   header("Content-Type: application/zip");
   header("Content-Disposition: attachment; filename=$file");
   $file="$data/$file";
   header("Content-Length: ".filesize($file));
   include("$file");
}
else{
   header("HTTP/1.0 404 Not Found");
   header("Content-Type: text/plain");
   echo "Xonotic Server: You need to download $file\n".
      "Client: Web server I need you to give me $file\n".
      "Web Server: $file does not even exist on this server\n".
      "Client: Why would you tell me I need a file you don't have?\n".
      "Web Server: The Xonotic Server must be experiencing an ID10T error.";
}
?>