Creating a byte array from a stream

Stream s;
byte[] b;

using (BinaryReader br = new BinaryReader(s))
{
    b = br.ReadBytes(s.Length);
}

public static byte[] ReadFully(Stream input)
{
    byte[] buffer = new byte[16*1024];
    using (MemoryStream ms = new MemoryStream())
    {
        int read;
        while ((read = input.Read(buffer, 0, buffer.Length)) > 0)
        {
            ms.Write(buffer, 0, read);
        }
        return ms.ToArray();
    }
}

public static byte[] ReadFully(Stream input)
{
    using (MemoryStream ms = new MemoryStream())
    {
        input.CopyTo(ms);
        return ms.ToArray();
    }
}

public static byte[] StreamToByteArray(Stream stream)
    {
        if (stream is MemoryStream)
        {
            return ((MemoryStream)stream).ToArray();
        }
        else
        {
            // Jon Skeet's accepted answer
            return ReadFully(stream);
        }
    }

MemoryStream ms = new MemoryStream();
file.PostedFile.InputStream.CopyTo(ms);
var byts = ms.ToArray();
ms.Dispose();

Stream s;
byte[] b;

if (s.Length > int.MaxValue) {
  throw new Exception("This stream is larger than the conversion algorithm can currently handle.");
}

using (var br = new BinaryReader(s)) {
  b = br.ReadBytes((int)s.Length);
}