From 136c0ed8859ef92321c5b784dffd19d5c1df420b Mon Sep 17 00:00:00 2001
From: Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>
Date: May 12 2024 23:23:30 +0000
Subject: man page generator: use $SOURCE_DATE_EPOCH if specified


When doing package builds, centpkg builds the man page using
pyrpkg.man_gen.generate(), and since the man page embeds the build timestamp in
the footer, the result is irreproducible. Use $SOURCE_DATE_EPOCH [1], if set, to
clamp the timestamp.

If SOURCE_DATE_EPOCH is set, but not a valid integer, this will raise an error.
I think this is appropriate, since this would most likely be a result of some
strange operator error.

Checked with:
$ PYTHONPATH=.:centpkg-0.8.2/src python centpkg-0.8.2/doc/centpkg_man_page.py
$ SOURCE_DATE_EPOCH=3001111 PYTHONPATH=.:centpkg-0.8.2/src python centpkg-0.8.2/doc/centpkg_man_page.py
The only difference is the date in the footer.

[1] https://reproducible-builds.org/docs/source-date-epoch/

Signed-off-by: Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>

---

diff --git a/pyrpkg/man_gen.py b/pyrpkg/man_gen.py
index b73dded..b739e42 100644
--- a/pyrpkg/man_gen.py
+++ b/pyrpkg/man_gen.py
@@ -65,8 +65,16 @@ class ManFormatter(object):
     @property
     def constants(self):
         """Global constants for man file templates"""
-        today = datetime.date.today()
+
+        source_date_epoch = os.environ.get('SOURCE_DATE_EPOCH')
+        if source_date_epoch:
+            today = datetime.datetime.fromtimestamp(int(source_date_epoch),
+                                                    tz=datetime.timezone.utc)
+        else:
+            today = datetime.date.today()
+
         today_manstr = today.strftime(r'%Y\-%m\-%d')
+
         return {'today': today_manstr,
                 'identity': self.identity,
                 'sourceurl': self.sourceurl}