Form downloads same ZIP over and over - php

Question

Thanks to the users community on this forum, I wrote a very simple web form that allows my user to view text files from within their Internet browser.
I have now two functions whereby the text files returned by the search are compressed into a ZIP. Here's my code
function getFilesFromSite() {
$result = null;
$ZIPresult = null;
if (empty($_POST['DBSite'])) { return null; }
$mydir = MYDIR;
$dir = opendir($mydir);
$DBSite = $_POST['DBSite'];
$getfilename = mysql_query("select filename from search_table where site='" . $DBSite . "'") or die(mysql_error());
while ($row = mysql_fetch_array($getfilename)) {
$filename = $row['filename'];
$result .= '<tr><td>' . $filename . '</td></tr>';
$ZIPresult .= basename($mydir) . '/' . $filename.' ';
}
if ($result) {
$result = "<table><tbody><tr><td>Search Results.</td></tr> $result</table>";
shell_exec("/bin/rm -f SearchResult.zip;/usr/bin/zip -9 SearchResult.zip ". $ZIPresult ." > /dev/null ");
//header for forced download
header("Pragma: public");
header("Cache-Control: no-cache, must-revalidate"); // HTTP/1.1
header("Expires: Sat, 26 Jul 1997 05:00:00 GMT"); // Date in the past
$fileName = 'SearchResult.zip';
header("Cache-Control: public");
header("Content-Description: File Transfer");
header("Content-Transfer-Encoding: binary");
header('Content-type: application/zip');
header("Content-length: " . filesize($fileName));
header('Content-Disposition: attachment; filename="' . $fileName . '"');
ob_start(); // Starts output buffering.
readfile($fileName); // "Outputs" the file.
$content = ob_get_flush(); // Grabs the output and assigns it to a variable.
print base64_encode($content);
}
function getFilesFromError() {
//Just a copy paste from above with different input parameter...
}
The problem is that the ZIP file with the contents from whatever search was done first gets downloaded over and over again. For instance, the results from getFilesFromSite() will always get downloaded even though I did a search with getFilesFromError() afterwards.
I suspect my headers are incorrectly set but I am not sure where.
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

Using Base64 was actually not working for reasons well stated here. Instead, I turned zlib compression off and reverted back to using binary as output format. Finally, I set Content-Type to application/octet-stream in my header. Everything is working fine now ; here's my code:
function getFiles() {
ini_set('zlib.output_compression', 'Off');
$result = null;
$ZIPresult = null;
$cleanup = null;
$output = null;
$fileName = null;
//remove old zip if any
$cleanup = shell_exec("/bin/rm -f SearchResult.zip");
error_log("SHELL OUTPUT=>" . $cleanup, 0);
//test
if (empty($_POST['DBRIDs'])) { return null; }
$mydir = MYDIR; // set from the CONSTANT
$dir = opendir($mydir);
$DBRIDs = $_POST['DBRIDs'];
$getfilename = mysql_query("select /*! SQL_CACHE */ filename from automation where rid in (" . $DBRIDs . ")") or die(mysql_error());
while ($row = mysql_fetch_array($getfilename)) {
$filename = $row['filename'];
$result .= '<tr><td>' . $filename . '</td></tr>';
$ZIPresult .= basename($mydir) . '/' . $filename.' ';
}
if ($result) {
$result = "<table><tbody><tr><td>Search Results.</td></tr> $result</table>";
$output = shell_exec("/usr/bin/zip SearchResult.zip ". $ZIPresult ." ");
error_log("SHELL OUTPUT=>" . $output, 0);
$fileName = 'SearchResult.zip';
error_log("ZIP FILENAME=>" . $fileName, 0);
if (file_exists($fileName)) {
//header for forced download
header('Content-Description: File Transfer');
header('Content-Type: application/octet-stream');
header('Content-Disposition: attachment; filename='.basename($fileName));
header('Content-Transfer-Encoding: binary');
header('Expires: 0');
header('Cache-Control: must-revalidate');
header('Pragma: public');
header('Content-Length: ' . filesize($fileName));
ob_clean();
flush();
readfile($fileName);
exit;
}
}
return $result;
}
Thanks to all for taking the time!!