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Diffstat (limited to 'cfgtree.mk')
| -rw-r--r-- | cfgtree.mk | 71 |
1 files changed, 71 insertions, 0 deletions
diff --git a/cfgtree.mk b/cfgtree.mk new file mode 100644 index 0000000..dea3943 --- /dev/null +++ b/cfgtree.mk @@ -0,0 +1,71 @@ +# +# Copyright (C) 2015 The Android Open Source Project +# +# Licensed under the Apache License, Version 2.0 (the "License"); +# you may not use this file except in compliance with the License. +# You may obtain a copy of the License at +# +# http://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software +# distributed under the License is distributed on an "AS IS" BASIS, +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +# See the License for the specific language governing permissions and +# limitations under the License. +# + +# This file provides a helper which loads the contents of a given file +# relative to a common root path. The helper ensures there is consistent +# path resolution for loading and error messaging for missing or empty +# files that are required. +# +# The primary usage of this file is for loading product-level configuration +# from plaintext files. An example usage in a makefile is: +# BRILLO_CRASH_SERVER := $(call cfgtree_get,brillo/crash_server,required) +# +# Note the use of an immediate assignment. If any other variable assignment is +# used, be sure to test that it resolves as and when expected. +# +# Populating the file is as simple as: +# cd $PRODUCT_DIR +# mkdir -p config/brillo +# echo https://some.server/handle/crash.cgi > config/brillo/crash_server +# +# Any lines beginning with '#' will be ignored, but if a '#' is required, it +# can be inserted by simply starting the line with a space which will be +# stripped off during the loading process. +# +# Note, there is no central mapping of variables to files. If any files will +# be used from different contexts, be sure to keep all users in sync. +# +# For any PRODUCT_* variable set using this mechanism, it is possible to +# verify a correct assignment by calling: +# +# m dump-products +# + +# Path to load from +CFGTREE_ROOT ?= $(LOCAL_PATH) +CFGTREE_PREFIX ?= config +CFGTREE_PATH := $(CFGTREE_ROOT)/$(CFGTREE_PREFIX) + +# Command to run to dump the file content. +CFGTREE_CMD ?= grep -v -e '^$(shell printf '\043')' + +# $(1) is the file to load from cfgtree +# +# Returns the output of $(CFGTREE_CMD) $(1)/$(2) if the file exists. +# Normally, this is all the text excluding lines starting with '#'. +# +define cfgtree-get +$(strip \ + $(if $(filter 0,$(words $(call cfgtree-get-if-exists,$(1)))),\ + $(error Required configuration file \ + $(CFGTREE_PREFIX)/$(1) is empty or missing.),\ + $(call cfgtree-get-if-exists,$(1)))\ +) +endef + +define cfgtree-get-if-exists +$(strip $(shell $(CFGTREE_CMD) $(CFGTREE_PATH)/$(1) 2>/dev/null)) +endef |