How to get the mime type of a file after using file_get_contents from a remote server

Question

I'm reading a file in PHP from Alfresco and then outputting it to the browser. The only problem is the mime type or the extension of the file. This is the code I'm using:

<?php
ob_start();
require_once("libs/AlfrescoConnect.php");

$nomeFile = rawurldecode($_GET['nomeFile']);    
$urlDownload = $_GET['urlDownload'];
$fileDownloadUrl =
    AlfrescoConnect::$serverPath. $urlDownload .
    "&attach=true&alf_ticket=".AlfrescoConnect::getTiket();
fb($fileDownloadUrl);

$cnt = file_get_contents($fileDownloadUrl);

header("Content-type: Application/octet-stream");
header('Cache-Control: must-revalidate');
header('Content-disposition: attachment; filename=' .$nomeFile);
echo($cnt);
exit();

echo("Impossibile trovare il file");

I receive the name of the file from the get because, I don't know how to get the name from alfresco. But I have to guess the mimetype somehow. If I echo $cnt in the first characters, there are references to the fact that it is a PDF (for example on screen I see

%PDF-1.3 %âãÏÓ 2 0 obj << /Length 3 0 R /Filter /CCITTFaxDecode /DecodeParms << /K 0 /Columns 2480 /Rows 3508 >> /Type /XObject /Subtype /Image /Width 2480 /Height 3508 /BitsPerComponent 1 /ColorSpace /DeviceGray >> stream

So there must be a way to get the mime type from it with a function.

Any help is appreciated!

Edit. If anyone is interested here is a class that you can use to get the extension from the mime type. http://www.ustrem.org/en/articles/mime-type-by-extension-en/

Answer 1

You can use the finfo::buffer() method: http://php.net/finfo_buffer.

<?php
$finfo = new finfo(FILEINFO_MIME);
echo $finfo->buffer($cnt) . PHP_EOL;

NOTE: You could optionally use the finfo_buffer procedural function if that suites you better than using the object-oriented methodology.