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LWN.net Weekly Edition for May 23, 2013
An "enum" for Python 3
An unexpected perf feature
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A look at the PyPy 2.0 release
The user and group bits wouldn't make much sense without the corresponding IDs.
Posted Nov 29, 2010 19:57 UTC (Mon) by Ross (subscriber, #4065)
However if you are going to count uid and gid those then it started with 2+2+1.5 = 5.5 bytes (sounds like the count in the article I agree), but it moved to 4+4+1.5 = 9.5 bytes. Since the point was that this was something which can't be changed (and hasn't except for POSIX ACLs which are mostly ignored) I don't think that's what the author meant.
But maybe it's true. He seems to be responding to comment so he can clear it up very easily.
Posted Nov 29, 2010 21:20 UTC (Mon) by neilbrown (subscriber, #359)
As you say, permission information only uses 5bytes and 1 bit (setuid etc are not permission bits, they are really the 'type' of the object and so are is some ways more closely related to IF_REG etc). Being that precise in the article would have been excessive I think. It is still true that the permissions were stored in 6 bytes. It is just that some room was left over for file type as well.
POSIX ACLs may well be mostly ignored, but ACLs are still the only direction being explored for making the permission model more complete. My point was simply that they have a storage cost which gets worse quickly, but worse than that it has a serious usability cost.
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