[OE-core] [PATCH v2 6/6] image.bbclass: support binary reproducibility

[Juro Bystricky]

Added a new task "reproducible_final_image_task".
If binary reproducibility is desired ($BUILD_REPRODUCIBLE_BINARIES" = "1"),
then recursivley modify mtimes of all files to a reproducible vale.
The value is obtained via REPRODUCIBLE_TIMESTAMP_ROOTFS.
This task is executed as the very last step in image creation, once all
the files in the image have been finalized.

[YOCTO#11176]

Signed-off-by: Juro Bystricky <juro.bystricky at intel.com>
---
 meta/classes/image.bbclass | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/meta/classes/image.bbclass b/meta/classes/image.bbclass
index 405fd73..c311de5 100644
--- a/meta/classes/image.bbclass
+++ b/meta/classes/image.bbclass
@@ -617,3 +617,15 @@ do_bundle_initramfs () {
 	:
 }
 addtask bundle_initramfs after do_image_complete
+
+reproducible_final_image_task () {
+    if [ "$BUILD_REPRODUCIBLE_BINARIES" = "1" ]; then
+        if [ "$REPRODUCIBLE_TIMESTAMP_ROOTFS" = "" ]; then
+            REPRODUCIBLE_TIMESTAMP_ROOTFS=`git log -1 --pretty=%ct`
+        fi
+        # Set mtime of all files to a reproducible value
+        bbnote "reproducible_final_image_task: mtime set to $REPRODUCIBLE_TIMESTAMP_ROOTFS"
+        find  ${IMAGE_ROOTFS} -exec touch -h  --date=@$REPRODUCIBLE_TIMESTAMP_ROOTFS {} \;
+    fi
+}
+IMAGE_PREPROCESS_COMMAND_append = " reproducible_final_image_task; "
-- 
2.7.4