Ihor Radchenko <yantar92@gmail.com> writes:

>> Ihor, I am afraid of collisions due to short input to md5. Long hash 
>> value gives false impression of high entropy but actually there are not 
>> so many variants for 1 or 2 characters strings. Either there is no point 
>> in making long name from short id or random string of appropriate length 
>> should be used instead.
>
> Random is not an option. If we use random string, how will we get the
> right attachment path on a second call? This function must return the
> same value given the same input.
>
> Having said that, I do agree (taking into account the other comment)
> that md5 may not be a very good idea. Maybe simply something like
> "__/id". Ideally, we should be able to recover the original id from the
> path to attachment.

I have updated the patch to use "__/id" when id is too short.
Any objections?