s3:idmap:autorid: make calculation in idmap_autorid_sid_to_id much more obvious
This is my attempt to make the sid->unix-id calculation much more obvious.
Especially with the introduction of the multi-range support an the originally
named "multiplier", the calculation
id = low_id + range_size * domain_number + rid - range_size * multiplier
was rather opaque to me.
What really happens here is this:
The rid is split into a reduced_rid part that is < rangesize and
a multiple of rangesize. This is given by the formula
rid = rid % range_size + (rid / range_size) * range_size
We define
reduced_rid := rid % range_size
and
domain_range_index := rid / range_size ( == the original multiplier)
and the original formula is equivalent to:
id = reduced_rid + low_id + range_number * range_size;
and reads
id = reduced_rid + range_minvalue
if we set range_minvalue := low_id + range_number * range_size.
Signed-off-by: Michael Adam <obnox@samba.org>
Reviewed-by: Christian Ambach <ambi@samba.org>