求帮忙修改个php curl模拟post请求内容后并下载文件

function curl_post($header,$data,$url){ $ch = curl_init(); $res= curl_setopt ($ch, CURLOPT_URL,$url); curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, FALSE); curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, FALSE); curl_setopt ($ch, CURLOPT_HEADER, 0); curl_setopt($ch, CURLOPT_POST, 1); curl_setopt($ch, CURLOPT_POSTFIELDS, $data); curl_setopt ($ch, CURLOPT_RETURNTRANSFER, 1); curl_setopt($ch,CURLOPT_HTTPHEADER,$header); $result = curl_exec ($ch); curl_close($ch); if ($result == NULL) {  return 0; } return $result;}   $url = 'http://www.bttiantang.com/download4.php' ;   $header = array("Host:www.bttiantang.com",  "Content-Type:application/x-www-form-urlencoded",  'User-Agent: Mozilla/4.0 (compatible; MSIE .0; Windows NT 6.1; Trident/4.0; SLCC2;)'); $data = 'action=download&id=26881&uhash=eecf3d3071a7b672c314bc39';$ret = curl_post($header, $data,$url);//需将内容显示修改为文件下载echo $ret;