Php Curl仅在不超过2天的情况下下载图像

我只想从远程服务器下载一个不超过两天的映像

我下面运行的代码正确吗？我想知道下载前上次修改的

数据

  $ch = curl_init($file_source);  // the file we are downloading
  curl_setopt($ch, CURLOPT_TIMEOUT, 20);
  curl_setopt($ch, CURLOPT_FILE, $wh);
  curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
  curl_setopt($ch, CURLOPT_FILETIME, true);
  curl_exec($ch);
  $headers = curl_getinfo($ch);
  $last_modified = $headers['filetime'];

  if ($last_modified != -1) { // unknown
      echo date("Y-m-d", $last_modified); //etc
  }


  curl_close($ch);
  fclose($wh);

$file\u source=>http://www.google.com/images/nav_logo29.png';
$ch=curl\u init（$file\u source）；
curl_setopt（$ch，CURLOPT_超时，20）；
curl_setopt（$ch，CURLOPT_FOLLOWLOCATION，true）；
curl_setopt（$ch，CURLOPT_FILETIME，true）；
curl_setopt（$ch，CURLOPT_头，true）；
curl_setopt（$ch，CURLOPT_RETURNTRANSFER，false）；
$file_source = 'http://www.google.com/images/nav_logo29.png';
$ch = curl_init($file_source);
curl_setopt($ch, CURLOPT_TIMEOUT, 20);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);

curl_setopt($ch, CURLOPT_FILETIME, true);
curl_setopt($ch, CURLOPT_HEADER, true);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, false); <-- don't download first
curl_exec($ch);
$headers = curl_getinfo($ch);
$last_modified = $headers['filetime'];

if ($last_modified != -1)
{
  if ($last_modified>time()-86400*2) <-- not older than 2 days
  {
    $ch2 = curl_init($file_source);
    $wh  = fopen('YOUR_PATH, 'w');
    curl_setopt($ch2, CURLOPT_FILE, $wh);
    curl_exec($ch2);
    curl_close($ch2);
    fclose($wh);
  }
}
curl_close($ch);