Add gen_notice module.

Refactor notices to support notices for multiple modules.

Enforce visibility and handle missing dependencies.

Bug: 213388645

Change-Id: Id6a81987f087419ad37d0cce57a71e8a7c4cd6e0
diff --git a/android/gen_notice.go b/android/gen_notice.go
new file mode 100644
index 0000000..f514975
--- /dev/null
+++ b/android/gen_notice.go
@@ -0,0 +1,207 @@
+// Copyright 2020 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 (
+	"fmt"
+	"strings"
+
+	"github.com/google/blueprint/proptools"
+)
+
+func init() {
+	RegisterGenNoticeBuildComponents(InitRegistrationContext)
+}
+
+// Register the gen_notice module type.
+func RegisterGenNoticeBuildComponents(ctx RegistrationContext) {
+	ctx.RegisterSingletonType("gen_notice_build_rules", GenNoticeBuildRulesFactory)
+	ctx.RegisterModuleType("gen_notice", GenNoticeFactory)
+}
+
+type genNoticeBuildRules struct{}
+
+func (s *genNoticeBuildRules) GenerateBuildActions(ctx SingletonContext) {
+	ctx.VisitAllModules(func(m Module) {
+		gm, ok := m.(*genNoticeModule)
+		if !ok {
+			return
+		}
+		if len(gm.missing) > 0 {
+			missingReferencesRule(ctx, gm)
+			return
+		}
+		out := BuildNoticeTextOutputFromLicenseMetadata
+		if proptools.Bool(gm.properties.Xml) {
+			out = BuildNoticeXmlOutputFromLicenseMetadata
+		} else if proptools.Bool(gm.properties.Html) {
+			out = BuildNoticeHtmlOutputFromLicenseMetadata
+		}
+		defaultName := ""
+		if len(gm.properties.For) > 0 {
+			defaultName = gm.properties.For[0]
+		}
+
+		modules := make([]Module, 0)
+		for _, name := range gm.properties.For {
+			mods := ctx.ModuleVariantsFromName(gm, name)
+			for _, mod := range mods {
+				if mod == nil {
+					continue
+				}
+				modules = append(modules, mod)
+			}
+		}
+		if ctx.Failed() {
+			return
+		}
+		out(ctx, gm.output, proptools.StringDefault(gm.properties.ArtifactName, defaultName), "", modules...)
+	})
+}
+
+func GenNoticeBuildRulesFactory() Singleton {
+	return &genNoticeBuildRules{}
+}
+
+type genNoticeProperties struct {
+	// For specifies the modules for which to generate a notice file.
+	For []string
+	// ArtifactName specifies the internal name to use for the notice file.
+	// It appears in the "used by:" list for targets whose entire name is stripped by --strip_prefix.
+	ArtifactName *string
+	// Stem specifies the base name of the output file.
+	Stem *string `android:"arch_variant"`
+	// Html indicates an html-format file is needed. The default is text. Can be Html or Xml but not both.
+	Html *bool
+	// Xml indicates an xml-format file is needed. The default is text. Can be Html or Xml but not both.
+	Xml *bool
+	// Gzipped indicates the output file must be compressed with gzip. Will append .gz to suffix if not there.
+	Gzipped *bool
+	// Suffix specifies the file extension to use. Defaults to .html for html, .xml for xml, or no extension for text.
+	Suffix *string
+	// Visibility specifies where this license can be used
+	Visibility []string
+}
+
+type genNoticeModule struct {
+	ModuleBase
+	DefaultableModuleBase
+
+	properties genNoticeProperties
+
+	output  OutputPath
+	missing []string
+}
+
+func (m *genNoticeModule) DepsMutator(ctx BottomUpMutatorContext) {
+	if proptools.Bool(m.properties.Html) && proptools.Bool(m.properties.Xml) {
+		ctx.ModuleErrorf("can be html or xml but not both")
+	}
+	if !ctx.Config().AllowMissingDependencies() {
+		var missing []string
+		// Verify the modules for which to generate notices exist.
+		for _, otherMod := range m.properties.For {
+			if !ctx.OtherModuleExists(otherMod) {
+				missing = append(missing, otherMod)
+			}
+		}
+		if len(missing) == 1 {
+			ctx.PropertyErrorf("for", "no %q module exists", missing[0])
+		} else if len(missing) > 1 {
+			ctx.PropertyErrorf("for", "modules \"%s\" do not exist", strings.Join(missing, "\", \""))
+		}
+	}
+}
+
+func (m *genNoticeModule) getStem() string {
+	stem := m.base().BaseModuleName()
+	if m.properties.Stem != nil {
+		stem = proptools.String(m.properties.Stem)
+	}
+	return stem
+}
+
+func (m *genNoticeModule) getSuffix() string {
+	suffix := ""
+	if m.properties.Suffix == nil {
+		if proptools.Bool(m.properties.Html) {
+			suffix = ".html"
+		} else if proptools.Bool(m.properties.Xml) {
+			suffix = ".xml"
+		}
+	} else {
+		suffix = proptools.String(m.properties.Suffix)
+	}
+	if proptools.Bool(m.properties.Gzipped) && !strings.HasSuffix(suffix, ".gz") {
+		suffix += ".gz"
+	}
+	return suffix
+}
+
+func (m *genNoticeModule) GenerateAndroidBuildActions(ctx ModuleContext) {
+	if ctx.Config().AllowMissingDependencies() {
+		// Verify the modules for which to generate notices exist.
+		for _, otherMod := range m.properties.For {
+			if !ctx.OtherModuleExists(otherMod) {
+				m.missing = append(m.missing, otherMod)
+			}
+		}
+		m.missing = append(m.missing, ctx.GetMissingDependencies()...)
+		m.missing = FirstUniqueStrings(m.missing)
+	}
+	out := m.getStem() + m.getSuffix()
+	m.output = PathForModuleOut(ctx, out).OutputPath
+}
+
+func GenNoticeFactory() Module {
+	module := &genNoticeModule{}
+
+	base := module.base()
+	module.AddProperties(&base.nameProperties, &module.properties)
+
+	// The visibility property needs to be checked and parsed by the visibility module.
+	setPrimaryVisibilityProperty(module, "visibility", &module.properties.Visibility)
+
+	initAndroidModuleBase(module)
+	InitDefaultableModule(module)
+
+	return module
+}
+
+var _ OutputFileProducer = (*genNoticeModule)(nil)
+
+// Implements OutputFileProducer
+func (m *genNoticeModule) OutputFiles(tag string) (Paths, error) {
+	if tag == "" {
+		return Paths{m.output}, nil
+	}
+	return nil, fmt.Errorf("unrecognized tag %q", tag)
+}
+
+// missingReferencesRule emits an ErrorRule for missing module references.
+func missingReferencesRule(ctx BuilderContext, m *genNoticeModule) {
+	if len(m.missing) < 1 {
+		panic(fmt.Errorf("missing references rule requested with no missing references"))
+	}
+
+	ctx.Build(pctx, BuildParams{
+		Rule:        ErrorRule,
+		Output:      m.output,
+		Description: "notice for " + proptools.StringDefault(m.properties.ArtifactName, "container"),
+		Args: map[string]string{
+			"error": m.Name() + " references missing module(s): " + strings.Join(m.missing, ", "),
+		},
+	})
+}