From a5ed04c903c17da953ce89ce41c785bc605751aa Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Sat, 17 Jul 2021 19:11:20 -0700
Subject: doc: reproducible PDF.

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

* pdf-clobber-stamps.tl: New file.
---
 pdf-clobber-stamps.tl | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)
 create mode 100644 pdf-clobber-stamps.tl

(limited to 'pdf-clobber-stamps.tl')

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"))
-- 
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