Check if a file is archive (zip or rar) using php

Question

How can i check if a file is archived (zip or rar) without knowing the extension. I need to find it using php.

I cannot use Fileinfo because its not installed and installation of any other packages on the server its out of the question.

UPDATE:

Zip module its not installed and i cannot install extra packages. I don't want to use mime_content_type because its deprecated

Thank you

Answer 1

Output from od -c:

  0000000    R   a   r   ! 032  \a  \0 317 220   s  \0  \0  \r  \0  \0  \0

  0000000    P   K 003 004  \n  \0  \0  \0  \0  \0  \0  \0   !  \0  \0  \0

You could use something like this:

<?php

$fh = @fopen($argv[1], "r");

if (!$fh) {
  print "ERROR: couldn't open file.\n";
  exit(126);
}

$blob = fgets($fh, 5);

fclose($fh);

if (strpos($blob, 'Rar') !== false) {
  print "Looks like a Rar.\n";
} else
if (strpos($blob, 'PK') !== false) {
  print "Looks like a ZIP.\n";
} else {
  print "I dunno.\n";
  exit(1);
}

?>

And my output:

ghoti@baz:~ 423$ ./filephp.php A2.rar
Looks like a Rar.
ghoti@baz:~ 424$ ./filephp.php OLDIE.zip 
Looks like a ZIP.
ghoti@baz:~ 425$ ./filephp.php 1-11-1.PDF 
I dunno.
ghoti@baz:~ 426$ 

Answer 2

To test whether a file is a zip archive, you can attempt to open it as a zip using open_zip function. For rar, you need to have PECL rar (preferably version at least 2.0.0) installed - see http://php.net/manual/en/book.rar.php for more details. The code could look like this:

if(is_resource($zip = zip_open($filename)))
{
    zip_close($zip);
    //this is a zip archive
}
elseif(($rar = RarArchive::open($filename)) !== FALSE)
{
    $rar->close();
    //this is a rar archive
}
else
{
    //this is not a zip or rar archive
}

You may need to do a bit extra work if the archives are password-protected. Read the corresponding php manual pages for more details.