php上传文件，通过curl上传到远程服务器

/**
* 上传图片api
*
*/
public function upload(){
$result = array('code' => 0, 'message' => 'ok');
ini_set('upload_max_filesize', '20M');
ini_set('post_max_size', '20M');
ini_set('memory_limit', '128M');
//接收上传的远程地址
$url = isset($_POST['url']) ? trim($_POST['url']) : '';
if (empty($url)) {
$result['code'] = 40001;
$result['message'] = 'url不能为空';
Helper_Http::writeJson(200,$result);
}
$file = $_FILES['file'];
if ($file['error'] != 0) {
$result['code'] = 40001;
$result['message'] = '上传出错';
Helper_Http::writeJson(200,$result);
} else {
$filename = $file['name'];
$tmpfile = $file['tmp_name'];
$filetype = $file['type'];
$data = $this->upload_file($url, $filename, $tmpfile, $filetype);
echo $data;
die;
}
}

/**
* curl上传文件
*
* @param unknown $url
* @param unknown $filename
* @param unknown $path
* @param unknown $type
*/
function upload_file($url,$filename,$path,$type){
//php 5.5以上的用法
if (class_exists('\CURLFile')) {
$data = array('file' => new \CURLFile(realpath($path),$type,$filename));
} else {
$data = array(
'file'=>'@'.realpath($path).";type=".$type.";filename=".$filename
);
}
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_POST, true );
curl_setopt($ch, CURLOPT_POSTFIELDS, $data);
curl_setopt($ch, CURLOPT_HEADER, false);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$return_data = curl_exec($ch);
curl_close($ch);
echo $return_data;
}