Re: [patch] objcopy embeds the current time and ignores SOURCE_DATE_EPOCH making the output unreproducible

[Nick Clifton <nickc@redhat.com>]

Hi Johannes,

>>     * Updating the description of the --timestamp command line option in
>>       ld/ld.texi to mention that if SOURCE_DATE_EPOCH is defined in the
>>      environment then this will be used instead of the current time.
> 
> I'm a bit confused here. I'm fixing objcopy but am supposed to edit ld/ld.texi?

Ah - I think that we were both confused.  You see the code that you are patching
in bfd/peXXigen.c is used by both the linker and objcopy.  I was tracking down
where the timestamp field in the pe_data_type structure was set, and I got diverted
to ld/emultempl/pe.em, which is why I thought about updating the linker documentation.

So anyway, both the linker documentation *and* the objcopy documentation need to
be updated...

There is also the minor issue that there is no way to undo the effects of the
-p/--preserve-dates command line option.  This can be an issue for complex build
systems that like to build up command lines in stages, allowing later stages to
override the effects of earlier stages.  But that is not something that affects
the review of your patch.

> Also, that file does not contain docs for a --timestamp command line option. Do
> you mean the --insert-timestamp option?

I did.  Sorry.

> Also, there is another instance of something calling time(0) in ld/pe-dll.c. I
> don't know what that does. Does it need fixing as well?

Good catch.  Yes that will need the same kind of change as peXXigen.c.

If you could resubmit your patch (to the list) with these changes and accompanied
by a DCO then I will approve and apply it.

Cheers
   Nick