Bug#890734: texlive-metapost: mpost does not honour SOURCE_DATE_EPOCH

[Gero Treuner <gt_72_debian.org@innocircle.com>]

Hi all,

As earlier Metapost user I have it installed and just saw the call for
help while updating my system.

According to the discussion and supposed plan and SOURCE_DATE_EPOCH
page I have a patch ready (see attachment), which follows the original
coding style. A test looks ok: %%CreationDate: honors the environment
variable, format is the same as before.

Note: Patch was made against the Buster version
(texlive-bin-2018.20181218.49446).

I'm not a Debian developer/maintainer, so please check and adopt it
according all your procedures (including QA).


Kind regards,
   Gero

diff -ur texlive-bin.orig/texk/web2c/mplibdir/mp.w texlive-bin/texk/web2c/mplibdir/mp.w
--- texlive-bin.orig/texk/web2c/mplibdir/mp.w	2019-08-03 22:48:47.000000000 +0200
+++ texlive-bin/texk/web2c/mplibdir/mp.w	2019-08-03 23:44:23.597334712 +0200
@@ -4350,7 +4350,11 @@
 
 @c
 static void mp_fix_date_and_time (MP mp) {
-  time_t aclock = time ((time_t *) 0);
+  time_t aclock;
+  char *source_date_epoch;
+  if ((source_date_epoch = getenv("SOURCE_DATE_EPOCH")) == NULL ||
+      (aclock = (time_t) strtoll(source_date_epoch, NULL, 10)) <= 0)
+    aclock = time ((time_t *) 0);
   struct tm *tmptr = localtime (&aclock);
   set_internal_from_number (mp_time, unity_t);
   number_multiply_int (internal_value(mp_time), (tmptr->tm_hour * 60 + tmptr->tm_min));