[bug#49517] [PATCH] gnu: txr: Build documentation and update to 265.

[Kaz Kylheku]

On 2021-07-18 03:36, Guillaume Le Vaillant wrote:
> Hi Kaz,
>
> I tried your patch and it doesn't fix all the timestamps in the
> environment used to build Guix packages:

OK,

I have a new patch which works for both the observed time
formats issued by Ghostscript, which I reproduced and tested.

Patch follows.

I extended the capture region to extract not only the XML
but that bit of PostScript with the dates which follows right
after it.

(I structured the script this way to avoid doing a regex search
and replace of the whole file, which is not only more time
consuming but risks more false positives than necessary.)

The replacement argument of regsub can be a function; the function
receives the original string and calculates its replacement.
So we can check for a trailing Z and act accordingly.

commit 920ae93cd768222db7387ee026f2d779d5e6de09 (HEAD -> master)
Author: Kaz Kylheku <kaz@kylheku.com>
Date:   Sat Jul 17 19:11:20 2021 -0700

    doc: reproducible PDF.

    * Makefile (txr-manpage.pdf): If SOURCE_DATE_EPOCH exists,
    then run pdf-clobber-stamps.tl.

    * pdf-clobber-stamps.tl: New file.

diff --git a/Makefile b/Makefile
index 0094985f..cac9b3c0 100644
--- a/Makefile
+++ b/Makefile
@@ -560,6 +560,7 @@ txr-manpage.html: txr.1 genman.txr
 txr-manpage.pdf: txr.1 checkman.txr
        $(TXR) checkman.txr $<
        tbl $< | pdfroff -ww -man --no-toc - > $@
+       [ $$SOURCE_DATE_EPOCH ] && $(TXR) pdf-clobber-stamps.tl || true

 #
 # Special targets used by ./configure
diff --git a/pdf-clobber-stamps.tl b/pdf-clobber-stamps.tl
new file mode 100644
index 00000000..78ea06c6
--- /dev/null
+++ b/pdf-clobber-stamps.tl
@@ -0,0 +1,22 @@
+(let* ((epoch (or (tointz (getenv "SOURCE_DATE_EPOCH")) 0))
+       (pdf (file-get-string "txr-manpage.pdf"))
+       (start (search-str pdf "<?xpacket begin="))
+       (end (if start (search-str pdf "/Creator(" start)))
+       (xml (if end [pdf start..end]))
+       (orig-len (len xml))
+       (isotime (time-string-utc epoch "%FT%T"))
+       (gstime (time-string-utc epoch "%Y%m%d%H%M%SZ0000")))
+  (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|[+\-]..:..)/
+            (ret `Date>@isotime@(if (ends-with "Z" @1) "Z" "+00:00")`))
+    (regsub #/Date\(D:..............[Z+\-]..../
+            `Date(D:@gstime`))
+  (assert (eql (len xml) orig-len))
+  (set [pdf start..end] xml)
+  (file-put-string "txr-manpage.pdf.temp" pdf)
+  (rename-path "txr-manpage.pdf.temp" "txr-manpage.pdf"))