Build cache.img on demand

Bug: 5153694
To build cache.img, set BOARD_CACHEIMAGE_FILE_SYSTEM_TYPE (required,
ext4 only for now), BOARD_CACHEIMAGE_PARTITION_SIZE (optional) in
BoardConfig.mk.

Change-Id: I1d8b91646aa1dba88285e008ad3335768bcbddd2
diff --git a/core/Makefile b/core/Makefile
index 2aab143..2a0b944 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -613,6 +613,8 @@
 $(if $(INTERNAL_USERIMAGES_EXT_VARIANT),$(hide) echo "fs_type=$(INTERNAL_USERIMAGES_EXT_VARIANT)" >> $(1))
 $(if $(BOARD_SYSTEMIMAGE_PARTITION_SIZE),$(hide) echo "system_size=$(BOARD_SYSTEMIMAGE_PARTITION_SIZE)" >> $(1))
 $(if $(BOARD_USERDATAIMAGE_PARTITION_SIZE),$(hide) echo "userdata_size=$(BOARD_USERDATAIMAGE_PARTITION_SIZE)" >> $(1))
+$(if $(BOARD_CACHEIMAGE_FILE_SYSTEM_TYPE),$(hide) echo "cache_fs_type=$(BOARD_CACHEIMAGE_FILE_SYSTEM_TYPE)" >> $(1))
+$(if $(BOARD_CACHEIMAGE_PARTITION_SIZE),$(hide) echo "cache_size=$(BOARD_CACHEIMAGE_PARTITION_SIZE)" >> $(1))
 $(if $(INTERNAL_USERIMAGES_SPARSE_EXT_FLAG),$(hide) echo "extfs_sparse_flag=$(INTERNAL_USERIMAGES_SPARSE_EXT_FLAG)" >> $(1))
 $(if $(mkyaffs2_extra_flags),$(hide) echo "mkyaffs2_extra_flags=$(mkyaffs2_extra_flags)" >> $(1))
 endef
@@ -767,7 +769,7 @@
 endif
 
 systemimage_intermediates := \
-	$(call intermediates-dir-for,PACKAGING,systemimage)
+    $(call intermediates-dir-for,PACKAGING,systemimage)
 BUILT_SYSTEMIMAGE := $(systemimage_intermediates)/system.img
 
 # $(1): output file
@@ -877,10 +879,10 @@
 # -----------------------------------------------------------------
 # data partition image
 INTERNAL_USERDATAIMAGE_FILES := \
-	$(filter $(TARGET_OUT_DATA)/%,$(ALL_DEFAULT_INSTALLED_MODULES))
+    $(filter $(TARGET_OUT_DATA)/%,$(ALL_DEFAULT_INSTALLED_MODULES))
 
 userdataimage_intermediates := \
-	$(call intermediates-dir-for,PACKAGING,userdata)
+    $(call intermediates-dir-for,PACKAGING,userdata)
 BUILT_USERDATAIMAGE_TARGET := $(PRODUCT_OUT)/userdata.img
 
 define build-userdataimage-target
@@ -926,6 +928,38 @@
 
 
 # -----------------------------------------------------------------
+# cache partition image
+ifdef BOARD_CACHEIMAGE_FILE_SYSTEM_TYPE
+INTERNAL_CACHEIMAGE_FILES := \
+    $(filter $(TARGET_OUT_CACHE)/%,$(ALL_DEFAULT_INSTALLED_MODULES))
+
+cacheimage_intermediates := \
+    $(call intermediates-dir-for,PACKAGING,cache)
+BUILT_CACHEIMAGE_TARGET := $(PRODUCT_OUT)/cache.img
+
+define build-cacheimage-target
+  $(call pretty,"Target cache fs image: $(INSTALLED_CACHEIMAGE_TARGET)")
+  @mkdir -p $(TARGET_OUT_CACHE)
+  @mkdir -p $(cacheimage_intermediates) && rm -rf $(cacheimage_intermediates)/cache_image_info.txt
+  $(call generate-userimage-prop-dictionary, $(cacheimage_intermediates)/cache_image_info.txt)
+  $(hide) PATH=$(foreach p,$(INTERNAL_USERIMAGES_BINARY_PATHS),$(p):)$$PATH \
+      ./build/tools/releasetools/build_image.py \
+      $(TARGET_OUT_CACHE) $(cacheimage_intermediates)/cache_image_info.txt $(INSTALLED_CACHEIMAGE_TARGET)
+  $(hide) $(call assert-max-image-size,$(INSTALLED_CACHEIMAGE_TARGET),$(BOARD_CACHEIMAGE_PARTITION_SIZE),yaffs)
+endef
+
+# We just build this directly to the install location.
+INSTALLED_CACHEIMAGE_TARGET := $(BUILT_CACHEIMAGE_TARGET)
+$(INSTALLED_CACHEIMAGE_TARGET): $(INTERNAL_USERIMAGES_DEPS) $(INTERNAL_CACHEIMAGE_FILES)
+	$(build-cacheimage-target)
+
+.PHONY: cacheimage-nodeps
+cacheimage-nodeps: | $(INTERNAL_USERIMAGES_DEPS)
+	$(build-cacheimage-target)
+
+endif # BOARD_CACHEIMAGE_FILE_SYSTEM_TYPE
+
+# -----------------------------------------------------------------
 # bring in the installer image generation defines if necessary
 ifeq ($(TARGET_USE_DISKINSTALLER),true)
 include bootable/diskinstaller/config.mk
@@ -1006,6 +1040,7 @@
 		$(INSTALLED_RECOVERYIMAGE_TARGET) \
 		$(INSTALLED_SYSTEMIMAGE) \
 		$(INSTALLED_USERDATAIMAGE_TARGET) \
+		$(INSTALLED_CACHEIMAGE_TARGET) \
 		$(INSTALLED_ANDROID_INFO_TXT_TARGET) \
 		$(built_ota_tools) \
 		$(APKCERTS_FILE) \
diff --git a/core/envsetup.mk b/core/envsetup.mk
index b564ce6..8457880 100644
--- a/core/envsetup.mk
+++ b/core/envsetup.mk
@@ -214,6 +214,8 @@
 TARGET_OUT_DATA_STATIC_LIBRARIES:= $(TARGET_OUT_STATIC_LIBRARIES)
 TARGET_OUT_DATA_NATIVE_TESTS := $(TARGET_OUT_DATA)/nativetest
 
+TARGET_OUT_CACHE := $(PRODUCT_OUT)/cache
+
 TARGET_OUT_VENDOR := $(PRODUCT_OUT)/$(TARGET_COPY_OUT_VENDOR)
 TARGET_OUT_VENDOR_EXECUTABLES:= $(TARGET_OUT_VENDOR)/bin
 TARGET_OUT_VENDOR_OPTIONAL_EXECUTABLES:= $(TARGET_OUT_VENDOR)/xbin
diff --git a/core/main.mk b/core/main.mk
index e35f228..97d3d7e 100644
--- a/core/main.mk
+++ b/core/main.mk
@@ -743,6 +743,9 @@
 .PHONY: userdatatarball
 userdatatarball: $(INSTALLED_USERDATATARBALL_TARGET)
 
+.PHONY: cacheimage
+cacheimage: $(INSTALLED_CACHEIMAGE_TARGET)
+
 .PHONY: bootimage
 bootimage: $(INSTALLED_BOOTIMAGE_TARGET)
 
@@ -757,6 +760,7 @@
 	$(INSTALLED_BOOTIMAGE_TARGET) \
 	$(INSTALLED_RECOVERYIMAGE_TARGET) \
 	$(INSTALLED_USERDATAIMAGE_TARGET) \
+	$(INSTALLED_CACHEIMAGE_TARGET) \
 	$(INSTALLED_FILES_FILE)
 
 # dist_files only for putting your library into the dist directory with a full build.
diff --git a/core/product.mk b/core/product.mk
index 26f365d..89c9e7b 100644
--- a/core/product.mk
+++ b/core/product.mk
@@ -227,6 +227,8 @@
 	BOARD_RECOVERYIMAGE_PARTITION_SIZE \
 	BOARD_SYSTEMIMAGE_PARTITION_SIZE \
 	BOARD_USERDATAIMAGE_PARTITION_SIZE \
+	BOARD_CACHEIMAGE_FILE_SYSTEM_TYPE \
+	BOARD_CACHEIMAGE_PARTITION_SIZE \
 	BOARD_FLASH_BLOCK_SIZE \
 	BOARD_SYSTEMIMAGE_PARTITION_SIZE \
 	BOARD_VENDOR_QCOM_GPS_LOC_API_HARDWARE \