[PATCH] image.bbclass: fix non-reproducible file time-stamps inside rootfs image

[venkata.pyla@toshiba-tsip.com]

From: venkata pyla <venkata.pyla@toshiba-tsip.com>

As part of reproducible-build work, the rootfs images generated on same
source should be identical between two builds.

In this commit it tries to solve one of the non-reproducible problem
i.e. the rootfs file time-stamps generated during build time are not
reproducible, it uses one of the solution provided in the debian
live-build image project (refer [1]), it fixes by finding all the
files/folders that are gernerated newly and set the time-stamp provided
by `SOURCE_DATE_EPOCH` environment variable.

[1] https://salsa.debian.org/live-team/live-build/-/merge_requests/218

Signed-off-by: venkata pyla <venkata.pyla@toshiba-tsip.com>
---
 meta/classes/image.bbclass | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/meta/classes/image.bbclass b/meta/classes/image.bbclass
index 813e1f3..f592a12 100644
--- a/meta/classes/image.bbclass
+++ b/meta/classes/image.bbclass
@@ -430,6 +430,15 @@ do_rootfs_finalize() {
             "${ROOTFSDIR}/etc/apt/sources.list.d/bootstrap.list"
 
         rm -f "${ROOTFSDIR}/etc/apt/sources-list"
+
+        # Set same time-stamps to the newly generated file/folders in the
+        # rootfs image for the purpose of reproducible builds.
+        test ! -z "${SOURCE_DATE_EPOCH}" && \
+            find ${ROOTFSDIR} -newermt \
+                "$(date -d@${SOURCE_DATE_EPOCH} '+%Y-%m-%d %H:%M:%S')" \
+                -printf "%y %p\n" \
+                -exec touch '{}' -h -d@${SOURCE_DATE_EPOCH} ';'
+
 EOSUDO
 }
 addtask rootfs_finalize before do_rootfs after do_rootfs_postprocess
-- 
2.20.1