build: Fix "adb shell" in recovery for system_root_image.
For system images that contain the root directory, "adb shell" in
recovery stops working if the image is mounted at "/system", because
sh now locates at /system/system/bin/sh. We fix the issue by mounting
the image on /system_root and create a symlink to /system_root/system
for /system.
Bug: 22855115
Change-Id: Ia6b257b75aeb67687c3909063d1725a23a5ccd60
diff --git a/core/Makefile b/core/Makefile
index ab58b83..d4dc002 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -895,6 +895,10 @@
$(hide) cp $(RECOVERY_INSTALL_OTA_KEYS) $(TARGET_RECOVERY_ROOT_OUT)/res/keys
$(hide) cat $(INSTALLED_DEFAULT_PROP_TARGET) $(recovery_build_prop) \
> $(TARGET_RECOVERY_ROOT_OUT)/default.prop
+ $(if $(filter true,$(BOARD_BUILD_SYSTEM_ROOT_IMAGE)), \
+ $(hide) mkdir -p $(TARGET_RECOVERY_ROOT_OUT)/system_root; \
+ rm -rf $(TARGET_RECOVERY_ROOT_OUT)/system; \
+ ln -sf /system_root/system $(TARGET_RECOVERY_ROOT_OUT)/system) # Mount the system_root_image to /system_root and symlink /system.
$(hide) $(MKBOOTFS) -d $(TARGET_OUT) $(TARGET_RECOVERY_ROOT_OUT) | $(MINIGZIP) > $(recovery_ramdisk)
$(if $(filter true,$(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_SUPPORTS_VBOOT)), \
$(hide) $(MKBOOTIMG) $(INTERNAL_RECOVERYIMAGE_ARGS) $(BOARD_MKBOOTIMG_ARGS) --output $(1).unsigned, \
