Add support for reproducible builds: $SOURCE_DATE_EPOCH

1 files changed, 13 insertions, 1 deletions

diff --git a/help2man.PL b/help2man.PL
index 664cc47..96146eb 100755
--- a/help2man.PL
+++ b/help2man.PL
@@ -366,11 +366,23 @@ for my $hash (\(%include, %replace, %append, %append_match))
 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 = program_basename $ARGV[0];
 my $package = $program;
 my $version;