Add se_versioned_policy module

se_versioned_policy module wraps version_sepolicy and generates mapping
files with Android.bp.

Bug: 33691272
Test: build
Change-Id: Iaba499db39b1214ef7b1f59c58232ec85d7c3bcb
diff --git a/build/soong/versioned_policy.go b/build/soong/versioned_policy.go
new file mode 100644
index 0000000..f25cd59
--- /dev/null
+++ b/build/soong/versioned_policy.go
@@ -0,0 +1,187 @@
+// Copyright (C) 2021 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.
+
+package selinux
+
+import (
+	"fmt"
+	"os"
+	"strconv"
+
+	"github.com/google/blueprint/proptools"
+
+	"android/soong/android"
+)
+
+func init() {
+	android.RegisterModuleType("se_versioned_policy", versionedPolicyFactory)
+}
+
+type versionedPolicyProperties struct {
+	// Base cil file for versioning.
+	Base *string `android:"path"`
+
+	// Output file name. Defaults to {name} if target_policy is set, {version}.cil if mapping is set
+	Stem *string
+
+	// Target sepolicy version. Can be a specific version number (e.g. "30.0" for R) or "current"
+	// (PLATFORM_SEPOLICY_VERSION). Defaults to "current"
+	Version *string
+
+	// If true, generate mapping file from given base cil file. Cannot be set with target_policy.
+	Mapping *bool
+
+	// If given, version target policy file according to base policy. Cannot be set with mapping.
+	Target_policy *string `android:"path"`
+
+	// Cil files to be filtered out by the filter_out tool of "build_sepolicy".
+	Filter_out []string `android:"path"`
+
+	// Cil files to which this mapping file depends. If specified, secilc checks whether the output
+	// file can be merged with specified cil files or not.
+	Dependent_cils []string `android:"path"`
+
+	// Whether this module is directly installable to one of the partitions. Default is true
+	Installable *bool
+
+	// install to a subdirectory of the default install path for the module
+	Relative_install_path *string
+}
+
+type versionedPolicy struct {
+	android.ModuleBase
+
+	properties versionedPolicyProperties
+
+	installSource android.Path
+	installPath   android.InstallPath
+}
+
+// se_versioned_policy generates versioned cil file with "version_policy". This can generate either
+// mapping file for public plat policies, or associate a target policy file with the version that
+// non-platform policy targets.
+func versionedPolicyFactory() android.Module {
+	m := &versionedPolicy{}
+	m.AddProperties(&m.properties)
+	android.InitAndroidArchModule(m, android.DeviceSupported, android.MultilibCommon)
+	return m
+}
+
+func (m *versionedPolicy) installable() bool {
+	return proptools.BoolDefault(m.properties.Installable, true)
+}
+
+func (m *versionedPolicy) DepsMutator(ctx android.BottomUpMutatorContext) {
+	// do nothing
+}
+
+func (m *versionedPolicy) GenerateAndroidBuildActions(ctx android.ModuleContext) {
+	version := proptools.StringDefault(m.properties.Version, "current")
+	if version == "current" {
+		version = ctx.DeviceConfig().PlatformSepolicyVersion()
+	}
+
+	var stem string
+	if s := proptools.String(m.properties.Stem); s != "" {
+		stem = s
+	} else if proptools.Bool(m.properties.Mapping) {
+		stem = version + ".cil"
+	} else {
+		stem = ctx.ModuleName()
+	}
+
+	out := android.PathForModuleOut(ctx, stem)
+	rule := android.NewRuleBuilder(pctx, ctx)
+
+	if proptools.String(m.properties.Base) == "" {
+		ctx.PropertyErrorf("base", "must be specified")
+		return
+	}
+
+	versionCmd := rule.Command().BuiltTool("version_policy").
+		FlagWithInput("-b ", android.PathForModuleSrc(ctx, *m.properties.Base)).
+		FlagWithArg("-n ", version).
+		FlagWithOutput("-o ", out)
+
+	if proptools.Bool(m.properties.Mapping) && proptools.String(m.properties.Target_policy) != "" {
+		ctx.ModuleErrorf("Can't set both mapping and target_policy")
+		return
+	}
+
+	if proptools.Bool(m.properties.Mapping) {
+		versionCmd.Flag("-m")
+	} else if target := proptools.String(m.properties.Target_policy); target != "" {
+		versionCmd.FlagWithInput("-t ", android.PathForModuleSrc(ctx, target))
+	} else {
+		ctx.ModuleErrorf("Either mapping or target_policy must be set")
+		return
+	}
+
+	if len(m.properties.Filter_out) > 0 {
+		rule.Command().BuiltTool("build_sepolicy").
+			Text("filter_out").
+			Flag("-f").
+			Inputs(android.PathsForModuleSrc(ctx, m.properties.Filter_out)).
+			FlagWithOutput("-t ", out)
+	}
+
+	if len(m.properties.Dependent_cils) > 0 {
+		rule.Command().BuiltTool("secilc").
+			Flag("-m").
+			FlagWithArg("-M ", "true").
+			Flag("-G").
+			Flag("-N").
+			FlagWithArg("-c ", strconv.Itoa(PolicyVers)).
+			Inputs(android.PathsForModuleSrc(ctx, m.properties.Dependent_cils)).
+			Text(out.String()).
+			FlagWithArg("-o ", os.DevNull).
+			FlagWithArg("-f ", os.DevNull)
+	}
+
+	rule.Build("mapping", "Versioning mapping file "+ctx.ModuleName())
+
+	m.installSource = out
+	m.installPath = android.PathForModuleInstall(ctx, "etc", "selinux")
+	if subdir := proptools.String(m.properties.Relative_install_path); subdir != "" {
+		m.installPath = m.installPath.Join(ctx, subdir)
+	}
+	ctx.InstallFile(m.installPath, m.installSource.Base(), m.installSource)
+
+	if !m.installable() {
+		m.SkipInstall()
+	}
+}
+
+func (m *versionedPolicy) AndroidMkEntries() []android.AndroidMkEntries {
+	return []android.AndroidMkEntries{android.AndroidMkEntries{
+		OutputFile: android.OptionalPathForPath(m.installSource),
+		Class:      "ETC",
+		ExtraEntries: []android.AndroidMkExtraEntriesFunc{
+			func(ctx android.AndroidMkExtraEntriesContext, entries *android.AndroidMkEntries) {
+				entries.SetBool("LOCAL_UNINSTALLABLE_MODULE", !m.installable())
+				entries.SetPath("LOCAL_MODULE_PATH", m.installPath.ToMakePath())
+				entries.SetString("LOCAL_INSTALLED_MODULE_STEM", m.installSource.Base())
+			},
+		},
+	}}
+}
+
+func (m *versionedPolicy) OutputFiles(tag string) (android.Paths, error) {
+	if tag == "" {
+		return android.Paths{m.installSource}, nil
+	}
+	return nil, fmt.Errorf("Unknown tag %q", tag)
+}
+
+var _ android.OutputFileProducer = (*policyConf)(nil)