On Sat, Aug 10, 2013 at 6:09 PM, Glenn Fowler <[email protected]> wrote:
>
> On Sat, 10 Aug 2013 17:54:56 +0200 Irek Szczesniak wrote:
>> On Sat, Aug 10, 2013 at 5:44 PM, Glenn Fowler <[email protected]> wrote:
>> >
>> > On Sat, 10 Aug 2013 17:38:19 +0200 Irek Szczesniak wrote:
>> >> On Sat, Aug 10, 2013 at 5:34 PM, Glenn Fowler <[email protected]> 
>> >> wrote:
>> >> >
>> >> > On Sat, 10 Aug 2013 17:19:29 +0200 Irek Szczesniak wrote:
>> >> >> On Sat, Aug 10, 2013 at 3:36 PM, Glenn Fowler <[email protected]> 
>> >> >> wrote:
>> >> >> >
>> >> >> > it still has not been explained why special fs treatment like this
>> >> >> > goes into ksh and not src/lib/libast/something
>> >> >> > is this really something *only* ksh will trip over
>> >> >
>> >> >> IMO yes, because entering a NFSv4 xattr directory is unique for a
>> >> >> shell. Otherwise the only way to do it is to run /usr/bin/runat <obj>
>> >> >> <prog> which is cumbersome at best and useless if you have builtins.
>> >> >
>> >> > how is the chdir()/fchdir() done by cd(1) different from the 
>> >> > chdir()/fchdir()
>> >> > done by find(1) or tw(1) or any of the -R commands?
>> >
>> >> You can cd -@ into all filesystem objects and not only directories.
>> >> Links included. And they all have their own resource forks/XATTR.
>> >
>> > ok, but why should/shouldn't the other commands mentioned above be able to 
>> > the same?
>
>> Because it's a rare and rarely used ability and feature to deal with
>> resource forks/XATTR files? I do understand why Roland did it and
>> Cedric and my people own like it. We're both Apple shops in our labs
>> and the admins need a way to access file files in emergencies. But I'm
>> not convinced that putting resource fork/XATTR support into every
>> utility is a good idea.
>
> but isn't "putting resource fork/XATTR support into every utility" exactly 
> what cd -@ does?
> after all, 'cd -@ barf; ls' will affect ls -- will ls need to know its inside 
> a fork?

No. I don't think so.

>
> I'm balking at this because I know (but can't enumerate) that -@ infects more 
> than cd(1)
> and the patches for cd -@ are fragile (not the patcher's fault, its weirdnix)

Weirdnix here is that you cd(1) into a file. But we've seen this
before with reiser4, smbfs and samfs. That's why
fstat()/S_ISDIR(fs.st_mode) is a bad idea.

> when chunks of code like this are so fragile, at least I want to understand 
> what's going on
> including and especially the scope

What's fragile in this case? As long as you don't ask the pwd(1)
question in a XATTR directory 'all is well'.

>
> suppose we finally get cd -@ working to everone's satisfaction
> what is the inevitable "add -@ to foo" patch going to look like?
> the same fragility, the *same* code?

With ls(1) as the exception I don't remember or imagine another
consumer of -@. pax(1) doesn't count because its a filesystem in a
bottle.

Irek
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