Add timestamp to ramdisk.

Add a build.prop file for ramdisk. Properties uses the
name ro.[product.]bootimage*.

These ro.[product.]bootimage.* properties are also included in recovery
properties.

The file is installed to boot/etc/build.prop under ramdisk.

On devices with dedicated recovery partition, the file is
installed to ramdisk/, which is installed to the ramdisk in the boot
image. The file is NOT installed to recovery/root to prevent
collision.

On devices with recovery_as_boot, in addition to ramdisk/, it is also
installed to recovery/root, which is installed to the ramdisk in the
boot image.

Test: m bootimage and inspect output
Bug: 169169031
Bug: 162623577

Change-Id: I94b993ce3214356036d038b6db57c4e1b755c111

core/Makefile

@@ -1829,6 +1829,15 @@ $(INSTALLED_RECOVERY_BUILD_PROP_TARGET): \
 	$(hide) cat $(INSTALLED_SYSTEM_EXT_BUILD_PROP_TARGET) >> $@
 	$(call append-recovery-ui-properties,$(PRIVATE_RECOVERY_UI_PROPERTIES),$@)
 
+# Only install boot/etc/build.prop to recovery image on recovery_as_boot.
+# On device with dedicated recovery partition, the file should come from the boot
+# ramdisk.
+ifeq (true,$(BOARD_USES_RECOVERY_AS_BOOT))
+INSTALLED_RECOVERY_RAMDISK_BUILD_PROP_TARGET := $(TARGET_RECOVERY_ROOT_OUT)/$(RAMDISK_BUILD_PROP_REL_PATH)
+$(INSTALLED_RECOVERY_RAMDISK_BUILD_PROP_TARGET): $(INSTALLED_RAMDISK_BUILD_PROP_TARGET)
+	$(copy-file-to-target)
+endif
+
 ifeq (truetrue,$(strip $(BUILDING_VENDOR_BOOT_IMAGE))$(strip $(AB_OTA_UPDATER)))
   INTERNAL_RECOVERYIMAGE_ARGS := --ramdisk $(recovery_ramdisk)
 ifdef GENERIC_KERNEL_CMDLINE
@@ -1873,6 +1882,7 @@ $(recovery_ramdisk): $(MKBOOTFS) $(COMPRESSION_COMMAND_DEPS) \
 	    $(recovery_sepolicy) \
 	    $(INSTALLED_2NDBOOTLOADER_TARGET) \
 	    $(INSTALLED_RECOVERY_BUILD_PROP_TARGET) \
+	    $(INSTALLED_RECOVERY_RAMDISK_BUILD_PROP_TARGET) \
 	    $(recovery_resource_deps) \
 	    $(recovery_fstab)
 	# Making recovery image

core/main.mk

@@ -1739,6 +1739,7 @@ else ifeq (,$(TARGET_BUILD_UNBUNDLED))
     $(INSTALLED_PRODUCT_BUILD_PROP_TARGET):build.prop-product \
     $(INSTALLED_ODM_BUILD_PROP_TARGET):build.prop-odm \
     $(INSTALLED_SYSTEM_EXT_BUILD_PROP_TARGET):build.prop-system_ext \
+    $(INSTALLED_RAMDISK_BUILD_PROP_TARGET):build.prop-ramdisk \
     $(BUILT_TARGET_FILES_PACKAGE) \
     $(INSTALLED_ANDROID_INFO_TXT_TARGET) \
     $(INSTALLED_MISC_INFO_TARGET) \

core/sysprop.mk

@@ -429,3 +429,13 @@ $(eval $(call build-properties,\
     $(_prop_files_),\
     $(_prop_vars_),\
     $(empty)))
+
+# ----------------------------------------------------------------
+# ramdisk/boot/etc/build.prop
+#
+
+RAMDISK_BUILD_PROP_REL_PATH := boot/etc/build.prop
+INSTALLED_RAMDISK_BUILD_PROP_TARGET := $(TARGET_RAMDISK_OUT)/$(RAMDISK_BUILD_PROP_REL_PATH)
+$(eval $(call build-properties,\
+    bootimage,\
+    $(INSTALLED_RAMDISK_BUILD_PROP_TARGET)))