GNU bug report logs - #7325
new test failure due to non-portability of printf formats like %05.3s

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Message #125 received at 7325 <at> debbugs.gnu.org (full text, mbox):

From: Pádraig Brady <P <at> draigBrady.com>
To: Jim Meyering <jim <at> meyering.net>
Cc: Paul Eggert <eggert <at> cs.ucla.edu>, Eric Blake <eblake <at> redhat.com>,
	7325 <at> debbugs.gnu.org
Subject: Re: bug#7325: new test failure due to non-portability of printf
	formats like %05.3s
Date: Fri, 12 Nov 2010 14:03:51 +0000

On 12/11/10 11:22, Jim Meyering wrote:
> Pádraig Brady wrote:
>> On 11/11/10 17:54, Paul Eggert wrote:
> ...
>>> It's
>>> not a big deal, but I still mildly prefer the * notation.
> 
> Same here.
> 
> However, here's an argument for using a different method, perhaps
> with a hard-coded mapping from common FS types to known precision:
> 
> Running these two commands with different ordering prints
> different results.  When the file with NS%10 == 0 comes first,
> stat suppresses the trailing 0(s):
> 
>     $ stat -c '%4n %.*Z' 3 9
>        3 1289555520.29981438
>        9 1289555520.300814502
> 
> After the first non-multiple-of-10 nanoseconds value,
> stat prints all trailing 0's:
> 
>     $ stat -c '%4n %.*Z' 9 3
>        9 1289555520.300814502
>        3 1289555520.299814380

That's just a special case of:
  find ... | xargs stat ...
So it's no worse that differences over multiple runs of stat IMHO

As for the general question of using hard coded resolutions for FS types.
It might be OK as long as you err'd on the side of too big rather than too small.
Though isn't everything going to tend towards nanoseconds going forward?

This feature is starting to seem a bit like over engineering
for what it gives us TBH.  If it was guaranteed to give us
an indication of the timestamp resolution, then OK
but otherwise I don't think it's worth it.

cheers,
Pádraig.

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