build: derive PKG_SOURCE_DATE_EPOCH from the unpacked source tree

Previously PKG_SOURCE_DATE_EPOCH came from a git log on the OpenWrt
package directory. That fails in shallow feed clones and in the SDK
(no .git), collapsing to the script's mtime and breaking .apk
reproducibility across SDK rebuilds and between buildbot and SDK.

With this comment, PKG_UNPACK generates a version.date file, later used to
determine a reproducible SOURCE_DATE_EPOCH. Since unpack happens after
download, the evaluation of SOURCE_DATE_EPOCH is now lazy, invoking the
`get_source_date_epoch.sh` script on every use.

While at it, drop export of PKG_SOURCE_DATE_EPOCH and clean it from the
ipkg-build script.

Link: https://github.com/openwrt/openwrt/issues/21579
Link: https://github.com/openwrt/openwrt/pull/21587
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Link: https://github.com/openwrt/openwrt/pull/23576
Signed-off-by: Paul Spooren <mail@aparcar.org>

diff --git a/include/package-defaults.mk b/include/package-defaults.mk
index af2db4712c96629e839dfb4dbf29ad7c453b6ae0..5bb6d1d2f465a673d06b31ed1adf21c47a7e8459 100644 (file)
--- a/include/package-defaults.mk
+++ b/include/package-defaults.mk
@@ -64,6 +64,7 @@ ifneq ($(strip $(PKG_UNPACK)),)
   define Build/Prepare/Default
        $(PKG_UNPACK)
        [ ! -d ./src/ ] || $(CP) ./src/. $(PKG_BUILD_DIR)
+       -find $(PKG_BUILD_DIR) -mindepth 1 -type f -printf '%T@\n' 2>/dev/null | head -n1 | cut -d. -f1 > $(PKG_BUILD_DIR)/version.date
        $(Build/Patch)
   endef
 endif

diff --git a/include/package-pack.mk b/include/package-pack.mk
index 96ec8fe8baf8e49d245f14ca6ec02ad0f12a2595..493619f7aa1e8117142c085bc13d31d0ccee2b77 100644 (file)
--- a/include/package-pack.mk
+++ b/include/package-pack.mk
@@ -439,7 +439,7 @@ $$(call addfield,Depends,$$(Package/$(1)/DEPENDS)
 )$$(call addfield,LicenseFiles,$(LICENSE_FILES)
 )$$(call addfield,Section,$(SECTION)
 )$$(call addfield,Require-User,$(USERID)
-)$$(call addfield,SourceDateEpoch,$(PKG_SOURCE_DATE_EPOCH)
+)$$(call addfield,SourceDateEpoch,$$(PKG_SOURCE_DATE_EPOCH)
 )$$(call addfield,URL,$(URL)
 )$$(if $$(ABIV_$(1)),ABIVersion: $$(ABIV_$(1))
 )$(if $(PKG_CPE_ID),CPE-ID: $(PKG_CPE_ID)
@@ -453,8 +453,7 @@ $(_endef)
     $$(PACK_$(1)) : export CONTROL=$$(Package/$(1)/CONTROL)
     $$(PACK_$(1)) : $(call shexport,Package/$(1)/description)
     $$(PACK_$(1)) : export PATH=$$(TARGET_PATH_PKG)
-    $$(PACK_$(1)) : export PKG_SOURCE_DATE_EPOCH:=$(PKG_SOURCE_DATE_EPOCH)
-    $$(PACK_$(1)) : export SOURCE_DATE_EPOCH:=$(PKG_SOURCE_DATE_EPOCH)
+    $$(PACK_$(1)) : export SOURCE_DATE_EPOCH=$$(PKG_SOURCE_DATE_EPOCH)
     $(PKG_INFO_DIR)/$(1).provides $$(PACK_$(1)): $(STAMP_BUILT) $(INCLUDE_DIR)/package-pack.mk
        rm -rf $$(IDIR_$(1))
 ifeq ($$(CONFIG_USE_APK),)

diff --git a/include/package.mk b/include/package.mk
index f3c4373249ca29e263ae6cf117f8f102e2df0120..cad8dc922f217218b757e71484977b1acc997019 100644 (file)
--- a/include/package.mk
+++ b/include/package.mk
@@ -15,7 +15,8 @@ PKG_SKIP_DOWNLOAD=$(USE_SOURCE_DIR)$(USE_GIT_TREE)$(USE_GIT_SRC_CHECKOUT)
 
 MAKE_J:=$(if $(MAKE_JOBSERVER),$(MAKE_JOBSERVER) $(if $(filter 3.% 4.0 4.1,$(MAKE_VERSION)),-j))
 
-PKG_SOURCE_DATE_EPOCH:=$(if $(DUMP),,$(shell $(TOPDIR)/scripts/get_source_date_epoch.sh $(CURDIR)))
+PKG_SOURCE_DATE_EPOCH = $(if $(DUMP),,$(shell $(TOPDIR)/scripts/get_source_date_epoch.sh \
+       $(if $(wildcard $(PKG_BUILD_DIR)/version.date),$(PKG_BUILD_DIR),$(CURDIR))))
 
 ifeq ($(strip $(PKG_BUILD_PARALLEL)),0)
 PKG_JOBS?=-j1
@@ -324,7 +325,7 @@ define Build/CoreTargets
   ifneq ($(CONFIG_AUTOREMOVE),)
     compile:
                -touch -r $(PKG_BUILD_DIR)/.built $(PKG_BUILD_DIR)/.autoremove 2>/dev/null >/dev/null
-               $(FIND) $(PKG_BUILD_DIR) -mindepth 1 -maxdepth 1 -not '(' -type f -and -name '.*' -and -size 0 ')' -and -not -name '.pkgdir'  -print0 | \
+               $(FIND) $(PKG_BUILD_DIR) -mindepth 1 -maxdepth 1 -not '(' -type f -and -name '.*' -and -size 0 ')' -and -not -name '.pkgdir' -and -not -name 'version.date'  -print0 | \
                        $(XARGS) -0 rm -rf
   endif
 endef

diff --git a/scripts/ipkg-build b/scripts/ipkg-build
index d2beb41844175a81ade246fe927a886ae2ee679c..2e18194abdc654da1ace143eb716ca017382bff8 100755 (executable)
--- a/scripts/ipkg-build
+++ b/scripts/ipkg-build
@@ -15,9 +15,7 @@ FIND="${FIND:-$(command -v gfind)}"
 TAR="${TAR:-$(command -v tar)}"
 
 # try to use fixed source epoch
-if [ -n "$PKG_SOURCE_DATE_EPOCH" ]; then
-       TIMESTAMP=$(date --date="@$PKG_SOURCE_DATE_EPOCH")
-elif [ -n "$SOURCE_DATE_EPOCH" ]; then
+if [ -n "$SOURCE_DATE_EPOCH" ]; then
        TIMESTAMP=$(date --date="@$SOURCE_DATE_EPOCH")
 else
        TIMESTAMP=$(date)