tools: zip: fetch SOURCE_DATE_EPOCH directly

Remove "--mtime" option introduced in commit 18c9faa03211 ("tools: zip:
add option for reproducible archives") and instead fetch SOURCE_DATE_EPOCH
environment variable directly in the code.

Ref: https://sourceforge.net/p/infozip/patches/25/
Signed-off-by: Sungbo Eo <mans0n@gorani.run>

1 files changed, 41 insertions, 0 deletions

diff --git a/tools/zip/patches/011-reproducible-mtime.patch b/tools/zip/patches/011-reproducible-mtime.patch
new file mode 100644
index 0000000000..6ce8445e83
--- /dev/null
+++ b/tools/zip/patches/011-reproducible-mtime.patch
@@ -0,0 +1,41 @@
+From 501ae4e93fd6fa2f7d20d00d1b011f9006802eae Mon Sep 17 00:00:00 2001
+From: "Bernhard M. Wiedemann" <bwiedemann@suse.de>
+Date: Fri, 3 May 2019 16:32:24 +0200
+Subject: [PATCH] Override mtime with zip -X
+
+with SOURCE_DATE_EPOCH
+to allow for reproducible builds of .zip files
+
+See https://reproducible-builds.org/ for why this is good
+and https://reproducible-builds.org/specs/source-date-epoch/
+for the definition of this variable.
+
+Uses clamping to keep older mtimes than SOURCE_DATE_EPOCH intact.
+---
+ zipup.c | 8 ++++++++
+ 1 file changed, 8 insertions(+)
+
+--- a/zipup.c
++++ b/zipup.c
+@@ -414,6 +414,7 @@ struct zlist far *z;    /* zip entry to
+   ush tempcext = 0;
+   char *tempextra = NULL;
+   char *tempcextra = NULL;
++  const char *source_date_epoch;
+ 
+ 
+ #ifdef WINDLL
+@@ -674,6 +675,13 @@ struct zlist far *z;    /* zip entry to
+ 
+   } /* strcmp(z->name, "-") == 0 */
+ 
++  if (extra_fields == 0 && (source_date_epoch = getenv("SOURCE_DATE_EPOCH")) != NULL) {
++     time_t epoch = strtoull(source_date_epoch, NULL, 10);
++     if (epoch > 0) {
++       ulg epochtim = unix2dostime(&epoch);
++       if (z->tim > epochtim) z->tim = epochtim;
++     }
++  }
+   if (extra_fields == 2) {
+     unsigned len;
+     char *p;