PHP Curl Chunked How to write result to variable?

Question

PHP

Hello!
Please tell me why the callback does not write the result to the $server_output variable.
Thanks for any help!

// ...
  $response = getCurl($link, $headers, true);
  function getCurl($link, $headers, $chunked = false){
    if(!isset($link) || !isset($headers))
      { print 'Error: getCurl argument'; die(); };
    $server_output = '';
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, $link);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
    if($chunked){
      curl_setopt($ch, CURLOPT_WRITEFUNCTION, function($ch, $str){
        $server_output .= $str;
        // на этой строчке $server_output имеет только один последний чанк
        return strlen($str);
      });
      // на этой строчке $server_output уже пуста
      curl_exec($ch);
    }else{
      $server_output = curl_exec($ch);
    };
    curl_close($ch); return $server_output;
  };

and, if you move the callback into a separate function, it also does not write anything:

function getCurl($link, $headers, $chunked = false){
    if(!isset($link) || !isset($headers))
      { print 'Error: getCurl argument'; die(); };
    $server_output = '';
    $callback = function($ch, $str){
      $server_output .= $str;
      return strlen($str);
    };
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, $link);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
    if($chunked){
      curl_setopt($ch, CURLOPT_WRITEFUNCTION, $callback);
      curl_exec($ch);
    }else{
      $server_output = curl_exec($ch);
    };
    curl_close($ch); return $server_output;
  };

Answer 1

Попробуйте заменить на

global $server_output;
$GLOBALS["server_output"].=$str;

PS: для использования 'use' (и анонимных функций) необходимо PHP >=5.3.0

Answer 2

curl_setopt($ch, CURLOPT_WRITEFUNCTION, function($ch, $str) use ($server_output){