Re: On NFS, cp -a copies non-integer timestamp as integer timestamp?

[Paul Smith]

On Tue, 2007-05-15 at 04:21 +0000, David Wuertele wrote:

> Here's an example using gzip where the time gets truncated.  This is a very
> close reproduction of one of my actual problems --- I verified with strace 
> that
> gzip is using only the NFS filesystem in question.

Well, again, gzip is not the same as cp -a.  Gzip is setting the time
last modified on the file after it's been compressed to be whatever the
uncompressed file was (which is a bit odd to me, since the file IS
different, but whatever).

However, the traditional UNIX system call for setting timestamps on a
file, utime(2), uses time_t as the timestamp value, and time_t is
counted in seconds.  So, most likely gzip is using this system call to
set the timestamp, instead of the newer utimes(2) system call which
would allow sub-second timestamps to be set.

You should report this as a bug to the gzip folks and hopefully they'll
enhance gzip to support utimes(2) where available.

> I will give .LOW_RESOLUTION_TIME a try.  Is there a way to make this the
> default, rather than specifying it for every single one of my targets?

Unfortunately not.  It wouldn't be that hard to add this, but it's not
there today.  If you would like this ability please file an enhancement
request in the GNU make project on Savannah (http://savannah.gnu.org/)

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