0A prepended to BLOBs upon retrieval using PHP - php

Question

For better or worse, I am storing binary information in a database table and am having a problem retrieving it. Each BLOB has a newline prepended to it upon retrieval, at least, I believe it's upon retrieval, as the binary object in the table is exactly the same size as the source file.
I've searched for a similar problem to mine, and the closest I have found is this However, I am using PDO instead of mysql_* and I have checked for empty lines prior to the opening
Here's the retrieval function stored in a separate file that I'm including in my test:
(in raw.php):
function return_raw_rawid($raw_id) {
$data = array();
$aggregate_data = array();
$sql = "SELECT * FROM `raw` WHERE `raw_id` = :rawid";
try {
$db_obj = dbCore::getInstance();
$query = $db_obj->dbh->prepare($sql);
$query->bindValue(':rawid', $raw_id);
if ($query->execute()) {
while($results = $query->fetch(PDO::FETCH_ASSOC)) {
$data['raw_id'] = $results['raw_id'];
$data['filename'] = $results['filename'];
$data['mime_type'] = $results['mime_type'];
$data['file_size'] = $results['file_size'];
$data['file_data'] = $results['file_data'];
$data['test_id'] = $results['test_id'];
$data['user_id'] = $results['user_id'];
$data['time'] = date('Y-m-d H:i:s', $results['time']);
$aggregate_data[] = $data;
} // while
} // if
$query->closeCursor();
return $aggregate_data;
} catch (PDOException $ex) {
$errors[] = $ex;
} // catch
}
Here's the code I'm testing it with in a separate file:
<?php
include 'core/init.php'; // Contains protect_page() and includes for return_raw_rawid
protect_page();
$blob_id = 20;
$blob = return_raw_rawid($blob_id);
$data = ltrim($blob[0]['file_data']);
$name = ltrim($blob[0]['filename']);
$size = ltrim($blob[0]['file_size']);
$type = ltrim($blob[0]['mime_type']);
header("Content-type: $type");
header("Content-length: $size");
header("Content-disposition: attachment; filename=$name");
header("Content-Description: PHP Generated Data");
echo $data;
When I load this page in my browser, it will prompt me to download the file identified by blob_id and has the correct filename and type. However, upon downloading it and opening in ghex, I see that the first byte is '0A' Using cmp original_file downloaded_file I determine that the only difference is this first byte. Googling led me to the ltrim() function that I've (perhaps too) liberally applied above.
I can't tell for sure if this problem is not being caused during upload, though as I said before, I don't believe it is since the "file_size" value in phpmyadmin is exactly the same as the source file. I'm not sure if the use of the aggregate_data array in the retrieval function could be to blame or what.
Any help is greatly appreciated!

Answer 1

Are you sure those 4 header lines are being properly executed? 0x0A is the newline char. You could have a newline in your core/init.php triggering output, and the headers are never executed. With display_errors/error_reporting off, you'd never see the warnings about "headers not sent - output started at line X...".