From 2e3357d7f0d63f1caeb40d9644c2436a5cd0da5f Mon Sep 17 00:00:00 2001
From: David Terry <me@xwvvvvwx.com>
Date: Fri, 18 Oct 2019 10:23:11 +0200
Subject: [PATCH] help2man: add support for SOURCE_DATE_EPOCH

---
 doc/help2man | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/doc/help2man b/doc/help2man
index af4306f..4a64167 100755
--- a/doc/help2man
+++ b/doc/help2man
@@ -213,11 +213,23 @@ sub get_option_value;
 my $help_text   = get_option_value $ARGV[0], $help_option;
 $version_text ||= get_option_value $ARGV[0], $version_option;
 
+# By default the generated manual pages will include the current date.  This may
+# however be overriden by setting the environment variable $SOURCE_DATE_EPOCH
+# to an integer value of the seconds since the UNIX epoch.  This is primarily
+# intended to support reproducible builds (wiki.debian.org/ReproducibleBuilds)
+# and will additionally ensure that the output date string is UTC.
+my $epoch_secs = time;
+if (exists $ENV{SOURCE_DATE_EPOCH} and $ENV{SOURCE_DATE_EPOCH} =~ /^(\d+)$/)
+{
+    $epoch_secs = $1;
+    $ENV{TZ} = 'UTC';
+}
+
 # Translators: the following message is a strftime(3) format string, which in
 # the English version expands to the month as a word and the full year.  It
 # is used on the footer of the generated manual pages.  If in doubt, you may
 # just use %x as the value (which should be the full locale-specific date).
-my $date = enc strftime _("%B %Y"), localtime;
+my $date = enc strftime _("%B %Y"), localtime $epoch_secs;
 (my $program = $ARGV[0]) =~ s!.*/!!;
 my $package = $program;
 my $version;
-- 
2.23.0