Question

Using a custom DevExpress application our users are uploading PDF files which get stored in a VARBINARY(MAX) column on a MSSQL 2008 database.

I have LAMP box which successfully connects to that database using the FreeTDS driver.

I’m able to retrieve other types of information (images stored as blobs, dates, strings etc) but when I try to serve PDFs they become corrupted somehow.

If I do a comparison of the file before upload and after download using a hex editor I can see they are different (the string in the after shot matches what is on the db 128B08…)

The PHP I am using to serve the file:

<?php
header("Pragma: public");
header("Expires: 0");
header("Cache-Control: must-revalidate, post-check=0, pre-check=0");
header("Cache-Control: public"); 
header("Content-Description: File Transfer");
header("Content-type:application/pdf");
header("Content-Disposition:attachment;filename=" . $arr[0]['FileName']);
header("Content-Transfer-Encoding: binary");
echo $arr[0]['FileContent'];

The C# used to save the file to the db:

public void LoadFromStream(string fileName, Stream stream)
{
  Guard.ArgumentNotNull(stream, "stream");
  Guard.ArgumentNotNullOrEmpty(fileName, "fileName");
  FileName = fileName;
  byte[] bytes = new byte[stream.Length];
  stream.Read(bytes, 0, bytes.Length);
  Content = bytes;
}

public void SaveToStream(Stream stream)
{
  if (string.IsNullOrEmpty(FileName))
  {
    throw new InvalidOperationException();
  }
  stream.Write(Content, 0, Size);
  stream.Flush();
}

public byte[] Content
{
  get { return GetDelayedPropertyValue<byte[]>("Content"); }
  set
  {
    int oldSize = size;
    if (value != null)
    {
      size = value.Length;
    }
    else
    {
      size = 0;
    }
    SetDelayedPropertyValue<byte[]>("Content", value);
    OnChanged("Size", oldSize, size);
  }
}

I’ve read just about every article I can find by searching “php varbinary, php output stream, php varbinary stream, varbinary encoding”. Help or suggestions much appreciated!

Answer 1

There’s a couple of problems with this.

First off, the data stored in the database is in Hex format so you’ll need to convert that back to a byte array in your PHP code before serving it to the user.

Secondly, the hex reprisentation you’ve got in the database doesn’t seem to be correct for the PDF you’re using.

When I converted the PDF from a byte array to a hex reprisentation I got a very different looking Hex string that when converted back to a byte array, works fine.