Re: [Help-tar] [PATCH] Add --clamp-mtime option

[Jakob Bohm]

On 10/06/2015 08:08, Paul Eggert wrote:
> Jakob Bohm wrote:
>
> > This is because the timestamp manipulation is typically limited to
> > files that are going to be packaged, not to build intermediary files
> > (such as .o files).
>
> One solution is to update the timestamps of build intermediary files as
> well. Another is to save the time stamps of backdated files and to
> restore them after running 'tar'.  Both of these should be easy to do.

That would be a lot of logic to gather up all that data into a data
structure, restore it afterwards, and hope no-one is calling you via
make -j.  You also need to handle the possibility of a failed build or
the maintainer hitting ctrl-C or the laptop running out of battery
etc. etc.

> > And do remember that debian source packages are independent of any
> > source control systems (git, svn etc. etc.) that you may have been
> > using when you created the package.
>
> Sure, but the point is that you have some way of recording time stamps
> of source files, and you want those recorded time stamps to be in the
> tarball.  This is needed regardless of whether there's a --clamp-mtime
> option.

My point was that for purposes of dpkg, the most important ways are:

- The local filesystem timestamps during package development (where
 local changes are probably not yet checked into any repository).
- The timestamps in source packages when releasing/uploading (which
 need to function without access to any repository used by the
 maintainer).

> > --clamp-mtime preserves the timestamp of files that are *not*
> > modified/created by the package build and should thus keep the
> > timestamp from the source package.
>
> The method I'm proposing doesn't use --mtime and so doesn't need
> --clamp-mtime.

If using touch, you will then need some way to tell touch (or a touch
wrapper) to only backdate, not forward date.  --clamp-mtime is that way
for the "virtual touch" inside tar.


Enjoy

Jakob
--
Jakob Bohm, CIO, Partner, WiseMo A/S.  https://www.wisemo.com
Transformervej 29, 2860 Søborg, Denmark.  Direct +45 31 13 16 10
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