Question

I wrote a very simple web form that allows my user to view text files from within their Internet browser.

I implemented a feature whereby the text files returned by the search are compressed into a ZIP. Here’s my code

        function getFiles() {
         $result = null;
         $ZIPresult = null;
         if (empty($_POST['DBRIDs'])) { return null; }
         $mydir = MYDIR; 
         $dir = opendir($mydir);
         $DBRIDs = $_POST['DBRIDs'];
         $getfilename = mysql_query("select filename from search_table where rid in (" . $DBRIDs . ")") or die(mysql_error());
         while ($row = mysql_fetch_array($getfilename)) {
         $filename = $row['filename'];
         $result .= '<tr><td><a href="' . basename($mydir) . '/' . $filename . '" target="_blank">' . $filename . '</a></td></tr>';
         $ZIPresult .= basename($mydir) . '/' . $filename;
        } 
        if ($result) {
        $result = "<table><tbody><tr><td>Search Results.</td></tr> $result</table>";
       shell_exec("zip -9 SearchResult.zip ". $ZIPresult ." > /dev/null ");

$fileName = 'SearchResult.zip';
header("Cache-Control: public");
header("Content-Description: File Transfer");
header("Content-Transfer-Encoding: binary");
header('Content-type: application/zip');
header("Content-length: " . filesize($fileName));
header('Content-Disposition: attachment; filename="' . $fileName . '"');
readfile($fileName); 
        } return $result;
        }

It works great If I download the ZIP file from the server using FTP (for example) but I force the download from the page header, the ZIP is corrupted.

What am I missing? Thanks for your input.

PS: The new ZipArchive() library/class is not available on our production environment so I chose to use the Unix utility ZIP instead.

Answer 1

It might be an encoding problem. Try encoding it with Base64.

Header:
header('Content-Transfer-Encoding: base64');

Then, to throw the file base64_encoded()ed to the browser, try the following:

ob_start(); // Starts output buffering.
readfile($fileName); // "Outputs" the file.
$content = ob_get_clean(); // Grabs the output and assigns it to a variable.
print base64_encode($content); // Encodes and prints the content to the browser.

Note that simply base64_encode(readfile($fileName)) won’t work because readfile() outputs data but doesn’t return it.

Hope it helps!