Php 截断存储在Varbinary（max）中的文件

我正在尝试使用PHP5.4在SQLServer2008数据库中上传一个文件。除了大小超过64KB的文件外，下载相同文件的代码工作正常。当我下载一个超过64KB的文件时，它会被截断为64KB

当我在本地尝试同样的事情时，它工作得很好，但只在开发服务器上出现文件截断问题。该网站托管在linux环境中

我使用bin2hex（）函数转换文件内容，如下所示

$fileContent=file_get_contents($_FILES[$key]["tmp_name"]);                
$fileContent="0x".bin2hex($fileContent);

然后，在下载时，我使用以下代码

  private $fileContents = '';
  private $fileName = '';
  private $contentType = '';

  public function __construct()
  {
    //parent::__construct();
    if (Tools::getPostVar('documentID')!="")
    {
      ini_set ('mssql.textlimit', 2147483647);
      ini_set ('mssql.textsize', 2147483647);
      $this->getFile();
      $this->showFile();
    }
    else
      Tools::ThrowError('Document ID not set', 'Document ID not set');
  }

  private function getFile()
  {
     $cn  = new DbMobTool();
     $cn->bIsConnPersist = false;
     $cn->doQuery("exec stp_my_procedure ".Tools::getPostVar("documentID"));
     $rs = $cn->fetchAll();

     switch (Tools::getEnvironment()) {
         case 'local':
            $this->fileContents = hex2bin($rs[0]->document);
            break;
         case 'dev':
         case 'stage':
         case 'prod':
           $this->fileContents = $rs[0]->document;
           break;
       }

    $this->fileName = $rs[0]->document_name;

        $s = strrchr($this->fileName, ".");
        $s = substr($s, 1, 3);
        switch (strtolower($s))
        {
            case 'pdf':
                $this->contentType = 'application/pdf';
                break;
            case 'jpg':
                $this->contentType = 'image/pjpeg';
                break;
            case 'xls':
                $this->contentType = 'application/vnd.ms-excel';
                break;
            case 'ppt':
                $this->contentType = 'application/vnd.ms-powerpoint';
                break;
            default:
                $this->contentType = 'text/plain';
        }

    $cn->closeDbObject($rs);    
  }

  private function showFile()
  {
    ob_clean();
    ob_start();
    //header('Content-Description: File Transfer');
    //header('Expires: 0');
    //header("Content-Transfer-Encoding: binary");
    if ($this->contentType != '')
    {
      header ('Content-Type: ' . $this->contentType);
      header ('Content-Title: ' . $this->contentType);
    }
    if(strpos($_SERVER['HTTP_USER_AGENT'], 'MSIE')===false)
      header ('Content-Disposition: attachment; filename="' . $this->fileName . '"');
    else
      header ('Content-Disposition: attachment; filename="' . str_replace('+',' ',urlencode($this->fileName)) . '"');

    header('Pragma: public');
    header('Cache-Control: must-revalidate');
    //clean all levels of output buffering
    while (ob_get_level()) {
        ob_end_clean();
    }
    echo $this->fileContents;
    //ob_end_flush();  // Stops output buffering and 'flushes' output to client browser
  }

我花了很多时间来解决这个问题。不确定这是配置问题还是我在发布文件时遗漏了什么

提前谢谢