Re: Why is chmod(2)?

Jamie Lokier (lkd@tantalophile.demon.co.uk)
Wed, 22 Sep 1999 14:41:20 +0200


Kristian Koehntopp wrote:
> b. Is it possible?

Yes if you define an `O_NONE' flag -- i.e. as opposed to O_RDONLY etc.

All the problems with side effects due to open and lack of permissions
are avoided by that: O_NONE means "return me a cookie, don't do anything
else".

The different between stat() and lstat() is also covered nicely by
`O_NOFOLLOW', which we already have.

> a. Is this desireable?

For programs that call stat() on a lot of things, the added
overhead of open/fstat/close is probably significant.

For the rarer things like fchflags() which might arrive, perhaps O_NONE
this is a good idea. It is certainly simpler than the proposals to add
fchflags/chflags/lchflags.

And as you point out, it's possible to improve security this way.

I recommend coding a patch to find out if O_NONE is really as easy as it
seems.

-- Jamie

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