[Python-3000] Fix imghdr module for bytes

[Adam Olsen]

On 8/10/07, Victor Stinner <victor.stinner at haypocalc.com> wrote:
> Hi,
>
> I just see that function what() of imghdr module requires str type for
> argument h which is totally wrong! An image file is composed of bytes and not
> characters.
>
> Attached patch should fix it. Notes:
>  - I used .startswith() instead of h[:len(s)] == s
>  - I used h[0] == ord(b'P') instead of h[0] == b'P' because the second syntax
> doesn't work (see my other email "bytes: compare bytes to integer")
> - str is allowed but doesn't work: what() always returns None
>
> I dislike "h[0] == ord(b'P')", in Python 2.x it's simply "h[0] == 'P'". A
> shorter syntax would be "h[0] == 80" but I prefer explicit test. It's maybe
> stupid, we manipulate bytes and not character, so "h[0] == 80" is
> acceptable... maybe with a comment?

Try h[0:1] == b'P'.  Slicing will ensure it stays as a bytes object,
rather than just giving the integer it contains.

-- 
Adam Olsen, aka Rhamphoryncus