curl重写php file_get_contents

file_get_contents在连接不上的时候会提示Connection refused，有时候会带来不便；另外，curl的性能比file_get_contents高，所以用curl重写file_get_contents

function _file_get_contents($s) {
$ret = "";
$ch = curl_init($s);
curl_setopt($ch, CURLOPT_HEADER, 0);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_FRESH_CONNECT, true);
curl_setopt($ch, CURLOPT_TIMEOUT, 0);
$buffer = curl_exec($ch);
curl_close($ch);

if ($buffer === false || empty($buffer)) {
$ret = "";
} else {
$ret = $buffer;
}

return $ret;
}