From be6acba4dc5c9013a8f61fb2e9d2dbb976126aa8 Mon Sep 17 00:00:00 2001
From: Felix Fietkau <nbd@openwrt.org>
Date: Sun, 31 Jan 2016 23:29:16 +0000
Subject: [PATCH] build system: have tar use $SOURCE_DATE_EPOCH for --mtime

The --mtime argument to 'tar' sets the modification time for all files within
the archive, which determines the timestamp files will get when they are
extracted. In this case, rootfs and other tarballs will get mtimes which
correspond to the last commit timestamp of the build system, as reported by
git/subversion.

This is a step towards reproducible image builds.

Signed-off-by: bryan newbold <bnewbold@robocracy.org>
Signed-off-by: Alexander Couzens <lynxis@fe80.eu>
Signed-off-by: Felix Fietkau <nbd@openwrt.org>

SVN-Revision: 48586
---
 include/image.mk           | 8 ++++++--
 include/kernel-build.mk    | 4 +++-
 scripts/sysupgrade-nand.sh | 7 ++++++-
 3 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/include/image.mk b/include/image.mk
index 4eee4adfaf..8f81861fd0 100644
--- a/include/image.mk
+++ b/include/image.mk
@@ -186,7 +186,8 @@ ifneq ($(CONFIG_NAND_SUPPORT),)
 	[ -z "$(2)" ] || $(CP) "$(KDIR)/root.$(2)" "$(KDIR_TMP)/sysupgrade-$(1)/root"
 	[ -z "$(3)" ] || $(CP) "$(3)" "$(KDIR_TMP)/sysupgrade-$(1)/kernel"
 	(cd "$(KDIR_TMP)"; $(TAR) cvf \
-		"$(BIN_DIR)/$(IMG_PREFIX)-$(1)-$(2)-sysupgrade.tar" sysupgrade-$(1))
+		"$(BIN_DIR)/$(IMG_PREFIX)-$(1)-$(2)-sysupgrade.tar" sysupgrade-$(1) \
+			$(if $(SOURCE_DATE_EPOCH),--mtime="@$(SOURCE_DATE_EPOCH)")
    endef
 
 # $(1) board name
@@ -248,7 +249,10 @@ define Image/mkfs/cpiogz
 endef
 
 define Image/mkfs/targz
-	$(TAR) -czpf $(BIN_DIR)/$(IMG_PREFIX)$(if $(PROFILE_SANITIZED),-$(PROFILE_SANITIZED))-rootfs.tar.gz --numeric-owner --owner=0 --group=0 --sort=name -C $(TARGET_DIR)/ .
+	$(TAR) -czpf $(BIN_DIR)/$(IMG_PREFIX)$(if $(PROFILE_SANITIZED),-$(PROFILE_SANITIZED))-rootfs.tar.gz \
+		--numeric-owner --owner=0 --group=0 --sort=name \
+		$(if $(SOURCE_DATE_EPOCH),--mtime="@$(SOURCE_DATE_EPOCH)") \
+		-C $(TARGET_DIR)/ .
 endef
 
 E2SIZE=$(shell echo $$(($(CONFIG_TARGET_ROOTFS_PARTSIZE)*1024*1024)))
diff --git a/include/kernel-build.mk b/include/kernel-build.mk
index 8bfd9c89e3..a52c90d9e7 100644
--- a/include/kernel-build.mk
+++ b/include/kernel-build.mk
@@ -54,7 +54,9 @@ ifdef CONFIG_COLLECT_KERNEL_DEBUG
 		$(STAGING_DIR_ROOT)/lib/modules/$(LINUX_VERSION)/* \
 		$(KERNEL_BUILD_DIR)/debug/modules/
 	$(FIND) $(KERNEL_BUILD_DIR)/debug -type f | $(XARGS) $(KERNEL_CROSS)strip --only-keep-debug
-	$(TAR) c -C $(KERNEL_BUILD_DIR) debug | bzip2 -c -9 > $(BIN_DIR)/kernel-debug.tar.bz2
+	$(TAR) c -C $(KERNEL_BUILD_DIR) debug \
+		$(if $(SOURCE_DATE_EPOCH),--mtime="@$(SOURCE_DATE_EPOCH)") \
+		| bzip2 -c -9 > $(BIN_DIR)/kernel-debug.tar.bz2
   endef
 endif
 
diff --git a/scripts/sysupgrade-nand.sh b/scripts/sysupgrade-nand.sh
index 92b326cbe9..45b17daccd 100755
--- a/scripts/sysupgrade-nand.sh
+++ b/scripts/sysupgrade-nand.sh
@@ -56,7 +56,12 @@ echo "BOARD=${board}" > "${tmpdir}/sysupgrade-${board}/CONTROL"
 [ -z "${rootfs}" ] || cp "${rootfs}" "${tmpdir}/sysupgrade-${board}/root"
 [ -z "${kernel}" ] || cp "${kernel}" "${tmpdir}/sysupgrade-${board}/kernel"
 
-(cd "$tmpdir"; tar cvf sysupgrade.tar sysupgrade-${board})
+mtime=""
+if [ -n "$SOURCE_DATE_EPOCH" ]; then
+	mtime="--mtime=@${SOURCE_DATE_EPOCH}"
+fi
+
+(cd "$tmpdir"; tar cvf sysupgrade.tar sysupgrade-${board} ${mtime})
 err="$?"
 if [ -e "$tmpdir/sysupgrade.tar" ]; then
 	cp "$tmpdir/sysupgrade.tar" "$outfile"