Re: uid > 64k

["Pierre A. Humblet" <Pierre dot Humblet at ieee dot org>]

Christopher Faylor wrote:

> Couldn't you just keep track of the uids and ensure that you didn't
> duplicate any?

Yes, absolutely.
However there is no guarantee that users won't call separately mkpasswd -l 
and mkpasswd -d, or another mkpasswd -d other_domain, or mkpasswd -d -u
It would be desirable to return the same uid in all these cases.
Thus for a start I would not go that route, but use a simple deterministic
hash (as Max suggested).
Anyway it's just a temporary fix until we turn on uid32

BTW, the probability of no conflict if we randomly map 100 uids between 
10001 and 60000 is 1 * (1- 1/50000) * (1 - 2/50000) * ... * (1- 99/50000)
 = exp( 0 + ln(1 - 1/50000) + .... + ln( 1 - 99/50000))
 ~ exp (0 - 1/50000 - 2/50000  - ... - 99/50000)
 = exp ( - 99 * 100 / 2 / 50000)
 = exp ( - 0.099 )
 ~ 1 - .01
So in that already big case there is a 1% chance that there will be some
conflict.

The probability that a specific uid does not conflict with any of the others is
(1 - 1/50000) ^ 99 ~ (1 - 99/50000) ~ 1 - .002 
So the probability that there will be aliasing with the current user is 
about .2%   (and even then there a 50% probability that the aliasing won't hurt)
 
Pierre