[Toybox] [PATCH] chown/chgrp with unknown numeric ids

[darken]

> If it really bothers you, I can change it back. It just makes the
rangetest... sort of inconclusive.

Nah doesn't bother me at all. I was just curious and looking to learn about
some of these C/linux intricacies.
Thanks for the details!

2016-08-20 22:46 GMT+02:00 Rob Landley <rob at landley.net>:

> On 08/20/2016 06:01 AM, darken wrote:
> >     I was grinding through my todo list last night and fixed this, and
> only
> >     just noticed replying to your message that you'd attached a patch.
> >     (Oops. Sorry.)
> >
> >
> > :-|, well at least it's fixed.
> >
> >     The fixes look fairly similar. I need to update tests/chown.test and
> >
> >     tests/chgrp.test to actually check for this usefully. (Poking at
> >     that now.)
> >
> >
> > Why return `unsigned` instead of `uid_t`/`gid_t` from the get uid/gid
> > methods?
>
> Because it's hard to range check otherwise.
>
> Unsigned int is the underlying type in uid_t these days (there's a
> getuid32 and everything), and if somebody tries to select a numeric uid
> out of range I want to catch that rather than wrapping it. I dunno off
> the top of my head what the UID_T_MAX macros would be (didn't find one
> in
> http://pubs.opengroup.org/onlinepubs/009695399/basedefs/sys/stat.h.html
> and similar), and 1LL<<8*sizeof(x) is just awkward (and assumes it's
> unsigned, which it _is_ but I'm not sure it's _required_ to be?)
>
> I have a tendency to squash things to known types and operate on them,
> producing behavior that's at least consistent. Possibly inappropriate in
> this case...
>
> On old Linux systems you had 16 bit uid ranges, but that went away
> before the posix 2008 (openat) stuff went in, so I think we already
> don't support such systems. Ok, it's still a build config option in the
> kernel, CONFIG_UID16, but so is CONFIG_BINFMT_AOUT a.out binary support.
>
> And then there's the discussion of 65534 being the _other_ magic UID
> number in the kernel. uid is 0, nobody is 65534, and the kernel knows
> both: https://lwn.net/Articles/695478/
>
> Legacy from the 16 bit UID days.
>
> If it really bothers you, I can change it back. It just makes the range
> test... sort of inconclusive.
>
> > By the way, I have another patch for the test applet:
> > https://github.com/landley/toybox/pull/47
> > <https://github.com/landley/toybox/pull/47>
>
> Test is in pending for a reason, but I'll take a look at this after I
> finish adding tunctl and promoting getfattr/setfattr. (Much reading on
> how xattrs work. Whoever designed these APIs should be harmed.)
>
> Thanks,
>
> Rob
>
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