add prebuilt_kernel_modules module

prebuilt_kernel_modules is a build rule for processing and installing
kernel module files. The module files are processed by depmod to build
modules.{load|alias|deps|softdeps} files. Debug symbols are stripped
from the module files and then all the files are installed to
./lib/modules/<kernel_version> directory.

This is the Soong-equivalent of the 'build-image-kernel-modules-dir`
macro and is expected to replace it in the future.

Bug: 178980227
Test: m

Change-Id: I772ac816824921d275869e35b93a083d239a2450

kernel/prebuilt_kernel_modules_test.go

@@ -0,0 +1,129 @@
+// Copyright 2021 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 kernel
+
+import (
+	"io/ioutil"
+	"os"
+	"reflect"
+	"strings"
+	"testing"
+
+	"android/soong/android"
+	"android/soong/cc"
+)
+
+func testKernelModules(t *testing.T, bp string, fs map[string][]byte) (*android.TestContext, android.Config) {
+	bp = bp + `
+		cc_binary_host {
+			name: "depmod",
+			srcs: ["depmod.cpp"],
+			stl: "none",
+			static_executable: true,
+			system_shared_libs: [],
+		}
+	`
+	bp = bp + cc.GatherRequiredDepsForTest(android.Android)
+
+	fs["depmod.cpp"] = nil
+	cc.GatherRequiredFilesForTest(fs)
+
+	config := android.TestArchConfig(buildDir, nil, bp, fs)
+
+	ctx := android.NewTestArchContext(config)
+	ctx.RegisterModuleType("prebuilt_kernel_modules", prebuiltKernelModulesFactory)
+	ctx.PreArchMutators(android.RegisterDefaultsPreArchMutators)
+	cc.RegisterRequiredBuildComponentsForTest(ctx)
+
+	ctx.Register()
+	_, errs := ctx.ParseFileList(".", []string{"Android.bp"})
+	android.FailIfErrored(t, errs)
+	_, errs = ctx.PrepareBuildActions(config)
+	android.FailIfErrored(t, errs)
+
+	return ctx, config
+}
+
+func ensureListContains(t *testing.T, result []string, expected string) {
+	t.Helper()
+	if !android.InList(expected, result) {
+		t.Errorf("%q is not found in %v", expected, result)
+	}
+}
+
+func ensureContains(t *testing.T, result string, expected string) {
+	t.Helper()
+	if !strings.Contains(result, expected) {
+		t.Errorf("%q is not found in %q", expected, result)
+	}
+}
+
+func TestKernelModulesFilelist(t *testing.T) {
+	ctx, _ := testKernelModules(t, `
+		prebuilt_kernel_modules {
+			name: "foo",
+			srcs: ["*.ko"],
+			kernel_version: "5.10",
+		}
+	`,
+		map[string][]byte{
+			"mod1.ko": nil,
+			"mod2.ko": nil,
+		})
+
+	expected := []string{
+		"lib/module/5.10/mod1.ko",
+		"lib/module/5.10/mod2.ko",
+		"lib/module/5.10/modules.load",
+		"lib/module/5.10/modules.dep",
+		"lib/module/5.10/modules.softdep",
+		"lib/module/5.10/modules.alias",
+	}
+
+	var actual []string
+	for _, ps := range ctx.ModuleForTests("foo", "android_arm64_armv8-a").Module().PackagingSpecs() {
+		actual = append(actual, ps.RelPathInPackage())
+	}
+	actual = android.SortedUniqueStrings(actual)
+	expected = android.SortedUniqueStrings(expected)
+	if !reflect.DeepEqual(actual, expected) {
+		t.Errorf("\ngot: %v\nexpected: %v\n", actual, expected)
+	}
+}
+
+var buildDir string
+
+func setUp() {
+	var err error
+	buildDir, err = ioutil.TempDir("", "soong_kernel_test")
+	if err != nil {
+		panic(err)
+	}
+}
+
+func tearDown() {
+	os.RemoveAll(buildDir)
+}
+
+func TestMain(m *testing.M) {
+	run := func() int {
+		setUp()
+		defer tearDown()
+
+		return m.Run()
+	}
+
+	os.Exit(run())
+}