Add module based host-tools snapshot

Add new module:
host_snapshot {
    name: "host-snapshot"
    deps: [
      (list of host tools)
    ],
    ...
}

Package host tools using android.PackagingBase to capture host tools and transitive packaging data.
Add JSON meta data to snapshot that allows snapshot to be installed via development/vendor_snapshot/update.py

Add support to generate a fake host snapshot of all host modules that is used to detect required
modules via development/vendor_snapshot/update.py.

Bug: 192556798
Bug: 194799048
Bug: 192896149
Test: m HOST_FAKE_SNAPSHOT_ENABLE=true host-fake-snapshot dist -- check snapshot exists in dist

Change-Id: I849c4db801cd858408f6fe6a3ce69262a23a5be9
diff --git a/snapshot/host_snapshot.go b/snapshot/host_snapshot.go
new file mode 100644
index 0000000..2a25a00
--- /dev/null
+++ b/snapshot/host_snapshot.go
@@ -0,0 +1,221 @@
+// Copyright 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 snapshot
+
+import (
+	"encoding/json"
+	"fmt"
+	"path/filepath"
+	"sort"
+
+	"github.com/google/blueprint"
+	"github.com/google/blueprint/proptools"
+
+	"android/soong/android"
+)
+
+//
+// The host_snapshot module creates a snapshot of the modules defined in
+// the deps property.  The modules within the deps property (host tools)
+// are ones that return a valid path via HostToolPath() of the
+// HostToolProvider.  The created snapshot contains the binaries and any
+// transitive PackagingSpecs of the included host tools, along with a JSON
+// meta file.
+//
+// The snapshot is installed into a source tree via
+// development/vendor_snapshot/update.py, the included modules are
+// provided as preferred prebuilts.
+//
+// To determine which tools to include in the host snapshot see
+// host_fake_snapshot.go.
+
+func init() {
+	registerHostBuildComponents(android.InitRegistrationContext)
+}
+
+func registerHostBuildComponents(ctx android.RegistrationContext) {
+	ctx.RegisterModuleType("host_snapshot", hostSnapshotFactory)
+}
+
+// Relative installation path
+type RelativeInstallPath interface {
+	RelativeInstallPath() string
+}
+
+type hostSnapshot struct {
+	android.ModuleBase
+	android.PackagingBase
+
+	zipFile    android.OptionalPath
+	installDir android.InstallPath
+}
+
+func hostSnapshotFactory() android.Module {
+	module := &hostSnapshot{}
+	initHostToolsModule(module)
+	return module
+}
+func initHostToolsModule(module *hostSnapshot) {
+	android.InitPackageModule(module)
+	android.InitAndroidMultiTargetsArchModule(module, android.HostSupported, android.MultilibCommon)
+}
+
+var dependencyTag = struct {
+	blueprint.BaseDependencyTag
+	android.InstallAlwaysNeededDependencyTag
+	android.PackagingItemAlwaysDepTag
+}{}
+
+func (f *hostSnapshot) DepsMutator(ctx android.BottomUpMutatorContext) {
+	f.AddDeps(ctx, dependencyTag)
+}
+func (f *hostSnapshot) installFileName() string {
+	return f.Name() + ".zip"
+}
+
+// Create zipfile with JSON description, notice files... for dependent modules
+func (f *hostSnapshot) CreateMetaData(ctx android.ModuleContext, fileName string) android.OutputPath {
+	var jsonData []SnapshotJsonFlags
+	var metaPaths android.Paths
+
+	metaZipFile := android.PathForModuleOut(ctx, fileName).OutputPath
+
+	// Create JSON file based on the direct dependencies
+	ctx.VisitDirectDeps(func(dep android.Module) {
+		desc := hostBinJsonDesc(dep)
+		if desc != nil {
+			jsonData = append(jsonData, *desc)
+		}
+		if len(dep.EffectiveLicenseFiles()) > 0 {
+			noticeFile := android.PathForModuleOut(ctx, "NOTICE_FILES", dep.Name()+".txt").OutputPath
+			android.CatFileRule(ctx, dep.EffectiveLicenseFiles(), noticeFile)
+			metaPaths = append(metaPaths, noticeFile)
+		}
+
+	})
+	// Sort notice paths and json data for repeatble build
+	sort.Slice(jsonData, func(i, j int) bool {
+		return (jsonData[i].ModuleName < jsonData[j].ModuleName)
+	})
+	sort.Slice(metaPaths, func(i, j int) bool {
+		return (metaPaths[i].String() < metaPaths[j].String())
+	})
+
+	marsh, err := json.Marshal(jsonData)
+	if err != nil {
+		ctx.ModuleErrorf("host snapshot json marshal failure: %#v", err)
+		return android.OutputPath{}
+	}
+
+	jsonZipFile := android.PathForModuleOut(ctx, "host_snapshot.json").OutputPath
+	metaPaths = append(metaPaths, jsonZipFile)
+	rspFile := android.PathForModuleOut(ctx, "host_snapshot.rsp").OutputPath
+	android.WriteFileRule(ctx, jsonZipFile, string(marsh))
+
+	builder := android.NewRuleBuilder(pctx, ctx)
+
+	builder.Command().
+		BuiltTool("soong_zip").
+		FlagWithArg("-C ", android.PathForModuleOut(ctx).OutputPath.String()).
+		FlagWithOutput("-o ", metaZipFile).
+		FlagWithRspFileInputList("-r ", rspFile, metaPaths)
+	builder.Build("zip_meta", fmt.Sprintf("zipping meta data for %s", ctx.ModuleName()))
+
+	return metaZipFile
+}
+
+// Create the host tool zip file
+func (f *hostSnapshot) GenerateAndroidBuildActions(ctx android.ModuleContext) {
+	// Create a zip file for the binaries, and a zip of the meta data, then merge zips
+	depsZipFile := android.PathForModuleOut(ctx, f.Name()+"_deps.zip").OutputPath
+	modsZipFile := android.PathForModuleOut(ctx, f.Name()+"_mods.zip").OutputPath
+	outputFile := android.PathForModuleOut(ctx, f.installFileName()).OutputPath
+
+	f.installDir = android.PathForModuleInstall(ctx)
+
+	f.CopyDepsToZip(ctx, depsZipFile)
+
+	builder := android.NewRuleBuilder(pctx, ctx)
+	builder.Command().
+		BuiltTool("zip2zip").
+		FlagWithInput("-i ", depsZipFile).
+		FlagWithOutput("-o ", modsZipFile).
+		Text("**/*:" + proptools.ShellEscape(f.installDir.String()))
+
+	metaZipFile := f.CreateMetaData(ctx, f.Name()+"_meta.zip")
+
+	builder.Command().
+		BuiltTool("merge_zips").
+		Output(outputFile).
+		Input(metaZipFile).
+		Input(modsZipFile)
+
+	builder.Build("manifest", fmt.Sprintf("Adding manifest %s", f.installFileName()))
+	zip := ctx.InstallFile(f.installDir, f.installFileName(), outputFile)
+	f.zipFile = android.OptionalPathForPath(zip)
+
+}
+
+// Implements android.AndroidMkEntriesProvider
+func (f *hostSnapshot) AndroidMkEntries() []android.AndroidMkEntries {
+	if !f.zipFile.Valid() {
+		return []android.AndroidMkEntries{}
+	}
+
+	return []android.AndroidMkEntries{android.AndroidMkEntries{
+		Class:      "ETC",
+		OutputFile: f.zipFile,
+		DistFiles:  android.MakeDefaultDistFiles(f.zipFile.Path()),
+		ExtraEntries: []android.AndroidMkExtraEntriesFunc{
+			func(ctx android.AndroidMkExtraEntriesContext, entries *android.AndroidMkEntries) {
+				entries.SetString("LOCAL_MODULE_PATH", f.installDir.ToMakePath().String())
+				entries.SetString("LOCAL_INSTALLED_MODULE_STEM", f.installFileName())
+			},
+		},
+	}}
+}
+
+// Get host tools path and relative install string helpers
+func hostBinToolPath(m android.Module) android.OptionalPath {
+	if provider, ok := m.(android.HostToolProvider); ok {
+		return provider.HostToolPath()
+	}
+	return android.OptionalPath{}
+
+}
+func hostRelativePathString(m android.Module) string {
+	var outString string
+	if rel, ok := m.(RelativeInstallPath); ok {
+		outString = rel.RelativeInstallPath()
+	}
+	return outString
+}
+
+// Create JSON description for given module, only create descriptions for binary modueles which
+// provide a valid HostToolPath
+func hostBinJsonDesc(m android.Module) *SnapshotJsonFlags {
+	path := hostBinToolPath(m)
+	relPath := hostRelativePathString(m)
+	if path.Valid() && path.String() != "" {
+		return &SnapshotJsonFlags{
+			ModuleName:          m.Name(),
+			ModuleStemName:      filepath.Base(path.String()),
+			Filename:            path.String(),
+			Required:            append(m.HostRequiredModuleNames(), m.RequiredModuleNames()...),
+			RelativeInstallPath: relPath,
+		}
+	}
+	return nil
+}