Kaz Kylheku <kaz@kylheku.com> skribis:

> On 2021-07-17 15:51, Kaz Kylheku wrote:
>> On 2021-07-17 02:57, Guillaume Le Vaillant wrote:
>>> Hi,
>>> When testing the patch to build the HTML and PDF documentation,
>>> I noticed that the 'share/doc/txr-263/txr-manpage.pdf' file is not
>>> reproducible. There are some timestamps and UUIDs in it that change at
>>> each build (diffoscope output attached).
>>> Could you take a look at that and see if there's a way to make it
>>> reproducible?
>>> Thanks.
>> Hi Guillaume,
>> Thank you for your report. I don't see anything in the pdfroff 
>> documentation
>> about getting rid of this. I might use a program similar to this one
>> to just overwrite the UUIDs and dates:
>
> I've noticed that there are some dates in the document which
> respond to SOURCE_DATE_EPOCH:
>
>   2 0 obj
>   <</Producer(GPL Ghostscript 9.26)
>   /CreationDate(D:20210717203740-07'00')
>   /ModDate(D:20210717203740-07'00')
>   /Creator(groff version 1.22.3)>>endobj
>
> If I build with the SOURCE_DATE_EPOCH environment variable,
> these dates from Ghostscript follow that variable.
> That's why Guillaume isn't seeing an issue in that section
> of the file.

Hi Kaz,

I tried your patch and it doesn't fix all the timestamps in the
environment used to build Guix packages:
 - Timestamps have the "YYYY-MM-DDTHH:MM:SSZ" format instead of
   "YYYY-MM-DDTHH:MM:SS+00:00"
 - There are two "...Date(D:YYYYMMDDHHMMSSZ..." timestamps after the XML
   block, although SOURCE_DATE_EPOCH is set to 1 in the environment

With the following modified 'pdf-clobber-stamps.tl' the document becomes
reproducible with Guix (but probably not in some other environments,
depending on the timezone format):

--8<---------------cut here---------------start------------->8---
(let* ((epoch (or (tointz (getenv "SOURCE_DATE_EPOCH")) 0))
       (isotime (time-string-utc epoch "%FT%TZ"))
       (pdf (file-get-string "txr-manpage.pdf"))
       (start (search-str pdf "<?xpacket begin="))
       (end (if start (search-str pdf "<?xpacket end" start)))
       (xml (if end [pdf start..end]))
       (orig-len (len xml)))
  (unless xml
    (format *stderr* "XML block not found in PDF")
    (exit nil))
  (upd xml
    (regsub #/uuid:........-....-....-....-............/
            "uuid:00000000-0000-0000-0000-000000000000")
    (regsub #/Date>....-..-..T..:..:..Z/
            `Date>@isotime`))
  (assert (eql (len xml) orig-len))
  (set [pdf start..end] xml)
  (upd pdf
    (regsub #/Date\(D:..............Z/
            "Date(D:19700101000001Z"))
  (file-put-string "txr-manpage.pdf.temp" pdf)
  (rename-path "txr-manpage.pdf.temp" "txr-manpage.pdf"))
--8<---------------cut here---------------end--------------->8---