Upstream-Status: Backport
Signed-off-by: Ross Burton <ross.burton@intel.com>

From 59da5577bf8df441c6ca958e50fcb83228702764 Mon Sep 17 00:00:00 2001
From: Alejandro del Castillo <alejandro.delcastillo@ni.com>
Date: Thu, 12 Sep 2019 10:24:58 -0500
Subject: [PATCH] opkg-build: clamp mtimes to SOURCE_DATE_EPOCH

For reproducible builds, clamp mtimes bigger than SOURCE_DATE_EPOCH to
SOURCE_DATE_EPOCH (build generated files, usually).

Fixes bugzilla 13450

Signed-off-by: Alejandro del Castillo <alejandro.delcastillo@ni.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
---
 opkg-build | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/opkg-build b/opkg-build
index dcd2d68..2517a2b 100755
--- a/opkg-build
+++ b/opkg-build
@@ -297,9 +297,16 @@ mkdir $tmp_dir
 
 build_date="${SOURCE_DATE_EPOCH:-$(date +%s)}"
 
+mtime_args=""
+# --clamp-mtime requires tar > 1.28. Only use it if SOURCE_DATE_EPOCH is set, to avoid having a generic case dependency on tar > 1.28.
+# this setting will make sure files generated at build time have consistent mtimes, for reproducible builds.
+if [ ! -z "$SOURCE_DATE_EPOCH"  ]; then
+    mtime_args="--mtime=@$build_date --clamp-mtime"
+fi
+
 ( cd $pkg_dir/$CONTROL && find . -type f > $tmp_dir/control_list )
 ( cd $pkg_dir && find . -path ./$CONTROL -prune -o -print > $tmp_dir/file_list )
-( cd $pkg_dir && tar $ogargs $tsortargs --no-recursion -c $tarformat -T $tmp_dir/file_list | $compressor $compressorargs > $tmp_dir/data.tar.$cext )
+( cd $pkg_dir && tar $ogargs $tsortargs --no-recursion $mtime_args -c $tarformat -T $tmp_dir/file_list | $compressor $compressorargs > $tmp_dir/data.tar.$cext )
 ( cd $pkg_dir/$CONTROL && tar $ogargs $tsortargs --no-recursion --mtime=@$build_date -c $tarformat -T $tmp_dir/control_list | gzip $zipargs > $tmp_dir/control.tar.gz )
 rm $tmp_dir/file_list
 rm $tmp_dir/control_list
-- 
2.20.1