Description:
------------
When a PG large object is returned to the web browser from the database using pg_lo_read_all(db resource, object id) the returned object is modified as shown by the unix command cmp.

bash-2.05a$ cmp kat_y_justin.jpg kat_y_justin_dl.jpg 
kat_y_justin.jpg kat_y_justin_dl.jpg differ: char 1, line 1

File sizes are different but not drastically (between original and downloaded object).  Size is field number 1 below:

30877 Aug  3 14:37 kat_y_justin.jpg
30884 Aug  3 15:15 kat_y_justin_dl.jpg

Reproduce code:
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function send_object() {
   $db = do_db_connect();
   cdb_query($db, "begin");
   $res = pg_lo_open($db, $_POST['object_id'], 'r');
   header("Content-type: " . $_POST['file_type']);
   header("Content-Disposition: file; filename=" .       
           $_POST['filename']);
   header("Content-Transfer-Encoding: binary");
   pg_lo_read_all($res);
   pg_lo_close($res);
   cdb_query($db, "end");
   exit();
}

cdb_query(db resource, string) is just a SQL wrapper function.

Expected result:
----------------
The same large object (which can be retrieved by using command line psql) should be returned to browser.

Actual result:
--------------
A modified file is returned to the browser.