Add product_config module

product_config module will export productVariables struct (defined in
android/variable.go). Other modules can depend on product_Config module
to read product variables, without needing to update Soong.

Bug: 346214955
Test: build and see output of product_config module
Change-Id: I06e1d2716dc2a8b90984bb46c5fc901cd1ca5020

Android.bp

@@ -136,3 +136,8 @@ buildinfo_prop {
 all_apex_contributions {
     name: "all_apex_contributions",
 }
+
+product_config {
+    name: "product_config",
+    visibility: ["//visibility:private"],
+}

android/Android.bp

@@ -83,6 +83,7 @@ bootstrap_go_package {
         "plugin.go",
         "prebuilt.go",
         "prebuilt_build_tool.go",
+        "product_config.go",
         "proto.go",
         "provider.go",
         "raw_files.go",

android/product_config.go

@@ -0,0 +1,58 @@
+// Copyright 2024 Google Inc. All rights reserved.
+//
+// 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.
+
+package android
+
+import "github.com/google/blueprint/proptools"
+
+func init() {
+	ctx := InitRegistrationContext
+	ctx.RegisterModuleType("product_config", productConfigFactory)
+}
+
+type productConfigModule struct {
+	ModuleBase
+}
+
+func (p *productConfigModule) GenerateAndroidBuildActions(ctx ModuleContext) {
+	if ctx.ModuleName() != "product_config" || ctx.ModuleDir() != "build/soong" {
+		ctx.ModuleErrorf("There can only be one product_config module in build/soong")
+		return
+	}
+	outputFilePath := PathForModuleOut(ctx, p.Name()+".json").OutputPath
+
+	// DeviceProduct can be null so calling ctx.Config().DeviceProduct() may cause null dereference
+	targetProduct := proptools.String(ctx.Config().config.productVariables.DeviceProduct)
+	if targetProduct != "" {
+		targetProduct += "."
+	}
+	soongVariablesPath := PathForOutput(ctx, "soong."+targetProduct+"variables")
+	extraVariablesPath := PathForOutput(ctx, "soong."+targetProduct+"extra.variables")
+
+	rule := NewRuleBuilder(pctx, ctx)
+	rule.Command().BuiltTool("merge_json").
+		Output(outputFilePath).
+		Input(soongVariablesPath).
+		Input(extraVariablesPath).
+		rule.Build("product_config.json", "building product_config.json")
+
+	ctx.SetOutputFiles(Paths{outputFilePath}, "")
+}
+
+// product_config module exports product variables and extra variables as a JSON file.
+func productConfigFactory() Module {
+	module := &productConfigModule{}
+	InitAndroidModule(module)
+	return module
+}

scripts/Android.bp

@@ -291,6 +291,14 @@ python_binary_host {
     ],
 }
 
+python_binary_host {
+    name: "merge_json",
+    main: "merge_json.py",
+    srcs: [
+        "merge_json.py",
+    ],
+}
+
 python_binary_host {
     name: "buildinfo",
     main: "buildinfo.py",

scripts/merge_json.py

@@ -0,0 +1,62 @@
+#!/usr/bin/env python
+#
+# Copyright 2024 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.
+#
+"""A tool for merging two or more JSON files."""
+
+import argparse
+import logging
+import json
+import sys
+
+def parse_args():
+  """Parse commandline arguments."""
+
+  parser = argparse.ArgumentParser()
+  parser.add_argument("output", help="output JSON file", type=argparse.FileType("w"))
+  parser.add_argument("input", help="input JSON files", nargs="+", type=argparse.FileType("r"))
+  return parser.parse_args()
+
+def main():
+  """Program entry point."""
+  args = parse_args()
+  merged_dict = {}
+  has_error = False
+  logger = logging.getLogger(__name__)
+
+  for json_file in args.input:
+    try:
+      data = json.load(json_file)
+    except json.JSONDecodeError as e:
+      logger.error(f"Error parsing JSON in file: {json_file.name}. Reason: {e}")
+      has_error = True
+      continue
+
+    for key, value in data.items():
+      if key not in merged_dict:
+        merged_dict[key] = value
+      elif merged_dict[key] == value:
+        logger.warning(f"Duplicate key '{key}' with identical values found.")
+      else:
+        logger.error(f"Conflicting values for key '{key}': {merged_dict[key]} != {value}")
+        has_error = True
+
+  if has_error:
+    sys.exit(1)
+
+  json.dump(merged_dict, args.output)
+
+if __name__ == "__main__":
+  main()

ui/build/config.go

@@ -1488,6 +1488,15 @@ func (c *configImpl) SoongVarsFile() string {
 	}
 }
 
+func (c *configImpl) SoongExtraVarsFile() string {
+	targetProduct, err := c.TargetProductOrErr()
+	if err != nil {
+		return filepath.Join(c.SoongOutDir(), "soong.extra.variables")
+	} else {
+		return filepath.Join(c.SoongOutDir(), "soong."+targetProduct+".extra.variables")
+	}
+}
+
 func (c *configImpl) SoongNinjaFile() string {
 	targetProduct, err := c.TargetProductOrErr()
 	if err != nil {

ui/build/soong.go

@@ -694,6 +694,7 @@ func runSoong(ctx Context, config Config) {
 		}
 	}
 	distFile(ctx, config, config.SoongVarsFile(), "soong")
+	distFile(ctx, config, config.SoongExtraVarsFile(), "soong")
 
 	if !config.SkipKati() {
 		distGzipFile(ctx, config, config.SoongAndroidMk(), "soong")

ui/build/test_build.go

@@ -64,7 +64,8 @@ func testForDanglingRules(ctx Context, config Config) {
 	outDir := config.OutDir()
 	modulePathsDir := filepath.Join(outDir, ".module_paths")
 	rawFilesDir := filepath.Join(outDir, "soong", "raw")
-	variablesFilePath := filepath.Join(outDir, "soong", "soong.variables")
+	variablesFilePath := config.SoongVarsFile()
+	extraVariablesFilePath := config.SoongExtraVarsFile()
 
 	// dexpreopt.config is an input to the soong_docs action, which runs the
 	// soong_build primary builder. However, this file is created from $(shell)
@@ -95,6 +96,7 @@ func testForDanglingRules(ctx Context, config Config) {
 		if strings.HasPrefix(line, modulePathsDir) ||
 			strings.HasPrefix(line, rawFilesDir) ||
 			line == variablesFilePath ||
+			line == extraVariablesFilePath ||
 			line == dexpreoptConfigFilePath ||
 			line == buildDatetimeFilePath ||
 			line == bpglob ||