Refactor projectmetadata into separate package.

Replace regular expressions to extract fields from a text proto with
and actual parsed protobuf.

Refactor TestFS into its own package, and implement StatFS.

Test: m droid dist cts alllicensemetadata

Test: repo forall -c 'echo -n "$REPO_PATH  " && $ANDROID_BUILD_TOP/out/host/linux-x86/bin/compliance_checkmetadata . 2>&1' | fgrep -v PASS

Change-Id: Icd17a6a2b6a4e2b6ffded48e964b9c9d6e4d64d6

18 files changed, 1094 insertions, 54 deletions

diff --git a/tools/compliance/Android.bp b/tools/compliance/Android.bp
index 225f3a578b..2527df727b 100644
--- a/tools/compliance/Android.bp
+++ b/tools/compliance/Android.bp
@@ -18,6 +18,17 @@ package {
 }
 
 blueprint_go_binary {
+    name: "compliance_checkmetadata",
+    srcs: ["cmd/checkmetadata/checkmetadata.go"],
+    deps: [
+        "compliance-module",
+        "projectmetadata-module",
+        "soong-response",
+    ],
+    testSrcs: ["cmd/checkmetadata/checkmetadata_test.go"],
+}
+
+blueprint_go_binary {
     name: "compliance_checkshare",
     srcs: ["cmd/checkshare/checkshare.go"],
     deps: [
@@ -156,6 +167,8 @@ bootstrap_go_package {
         "test_util.go",
     ],
     deps: [
+        "compliance-test-fs-module",
+        "projectmetadata-module",
         "golang-protobuf-proto",
         "golang-protobuf-encoding-prototext",
         "license_metadata_proto",
diff --git a/tools/compliance/cmd/checkmetadata/checkmetadata.go b/tools/compliance/cmd/checkmetadata/checkmetadata.go
new file mode 100644
index 0000000000..c6c84e45a7
--- /dev/null
+++ b/tools/compliance/cmd/checkmetadata/checkmetadata.go
@@ -0,0 +1,148 @@
+// Copyright 2022 Google LLC
+//
+// 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 main
+
+import (
+	"bytes"
+	"flag"
+	"fmt"
+	"io"
+	"io/fs"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"android/soong/response"
+	"android/soong/tools/compliance"
+	"android/soong/tools/compliance/projectmetadata"
+)
+
+var (
+	failNoneRequested = fmt.Errorf("\nNo projects requested")
+)
+
+func main() {
+	var expandedArgs []string
+	for _, arg := range os.Args[1:] {
+		if strings.HasPrefix(arg, "@") {
+			f, err := os.Open(strings.TrimPrefix(arg, "@"))
+			if err != nil {
+				fmt.Fprintln(os.Stderr, err.Error())
+				os.Exit(1)
+			}
+
+			respArgs, err := response.ReadRspFile(f)
+			f.Close()
+			if err != nil {
+				fmt.Fprintln(os.Stderr, err.Error())
+				os.Exit(1)
+			}
+			expandedArgs = append(expandedArgs, respArgs...)
+		} else {
+			expandedArgs = append(expandedArgs, arg)
+		}
+	}
+
+	flags := flag.NewFlagSet("flags", flag.ExitOnError)
+
+	flags.Usage = func() {
+		fmt.Fprintf(os.Stderr, `Usage: %s {-o outfile} projectdir {projectdir...}
+
+Tries to open the METADATA.android or METADATA file in each projectdir
+reporting any errors on stderr.
+
+Reports "FAIL" to stdout if any errors found and exits with status 1.
+
+Otherwise, reports "PASS" and the number of project metadata files
+found exiting with status 0.
+`, filepath.Base(os.Args[0]))
+		flags.PrintDefaults()
+	}
+
+	outputFile := flags.String("o", "-", "Where to write the output. (default stdout)")
+
+	flags.Parse(expandedArgs)
+
+	// Must specify at least one root target.
+	if flags.NArg() == 0 {
+		flags.Usage()
+		os.Exit(2)
+	}
+
+	if len(*outputFile) == 0 {
+		flags.Usage()
+		fmt.Fprintf(os.Stderr, "must specify file for -o; use - for stdout\n")
+		os.Exit(2)
+	} else {
+		dir, err := filepath.Abs(filepath.Dir(*outputFile))
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "cannot determine path to %q: %s\n", *outputFile, err)
+			os.Exit(1)
+		}
+		fi, err := os.Stat(dir)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "cannot read directory %q of %q: %s\n", dir, *outputFile, err)
+			os.Exit(1)
+		}
+		if !fi.IsDir() {
+			fmt.Fprintf(os.Stderr, "parent %q of %q is not a directory\n", dir, *outputFile)
+			os.Exit(1)
+		}
+	}
+
+	var ofile io.Writer
+	ofile = os.Stdout
+	var obuf *bytes.Buffer
+	if *outputFile != "-" {
+		obuf = &bytes.Buffer{}
+		ofile = obuf
+	}
+
+	err := checkProjectMetadata(ofile, os.Stderr, compliance.FS, flags.Args()...)
+	if err != nil {
+		if err == failNoneRequested {
+			flags.Usage()
+		}
+		fmt.Fprintf(os.Stderr, "%s\n", err.Error())
+		fmt.Fprintln(ofile, "FAIL")
+		os.Exit(1)
+	}
+	if *outputFile != "-" {
+		err := os.WriteFile(*outputFile, obuf.Bytes(), 0666)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "could not write output to %q from %q: %s\n", *outputFile, os.Getenv("PWD"), err)
+			os.Exit(1)
+		}
+	}
+	os.Exit(0)
+}
+
+// checkProjectMetadata implements the checkmetadata utility.
+func checkProjectMetadata(stdout, stderr io.Writer, rootFS fs.FS, projects ...string) error {
+
+	if len(projects) < 1 {
+		return failNoneRequested
+	}
+
+	// Read the project metadata files from `projects`
+	ix := projectmetadata.NewIndex(rootFS)
+	pms, err := ix.MetadataForProjects(projects...)
+	if err != nil {
+		return fmt.Errorf("Unable to read project metadata file(s) %q from %q: %w\n", projects, os.Getenv("PWD"), err)
+	}
+
+	fmt.Fprintf(stdout, "PASS -- parsed %d project metadata files for %d projects\n", len(pms), len(projects))
+	return nil
+}
diff --git a/tools/compliance/cmd/checkmetadata/checkmetadata_test.go b/tools/compliance/cmd/checkmetadata/checkmetadata_test.go
new file mode 100644
index 0000000000..cf2090b4cc
--- /dev/null
+++ b/tools/compliance/cmd/checkmetadata/checkmetadata_test.go
@@ -0,0 +1,191 @@
+// Copyright 2022 Google LLC
+//
+// 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 main
+
+import (
+	"bytes"
+	"fmt"
+	"os"
+	"strings"
+	"testing"
+
+	"android/soong/tools/compliance"
+)
+
+func TestMain(m *testing.M) {
+	// Change into the parent directory before running the tests
+	// so they can find the testdata directory.
+	if err := os.Chdir(".."); err != nil {
+		fmt.Printf("failed to change to testdata directory: %s\n", err)
+		os.Exit(1)
+	}
+	os.Exit(m.Run())
+}
+
+func Test(t *testing.T) {
+	tests := []struct {
+		name           string
+		projects       []string
+		expectedStdout string
+	}{
+		{
+			name:           "1p",
+			projects:       []string{"firstparty"},
+			expectedStdout: "PASS -- parsed 1 project metadata files for 1 projects",
+		},
+		{
+			name:           "notice",
+			projects:       []string{"notice"},
+			expectedStdout: "PASS -- parsed 1 project metadata files for 1 projects",
+		},
+		{
+			name:           "1p+notice",
+			projects:       []string{"firstparty", "notice"},
+			expectedStdout: "PASS -- parsed 2 project metadata files for 2 projects",
+		},
+		{
+			name:           "reciprocal",
+			projects:       []string{"reciprocal"},
+			expectedStdout: "PASS -- parsed 1 project metadata files for 1 projects",
+		},
+		{
+			name:           "1p+notice+reciprocal",
+			projects:       []string{"firstparty", "notice", "reciprocal"},
+			expectedStdout: "PASS -- parsed 3 project metadata files for 3 projects",
+		},
+		{
+			name:           "restricted",
+			projects:       []string{"restricted"},
+			expectedStdout: "PASS -- parsed 1 project metadata files for 1 projects",
+		},
+		{
+			name:           "1p+notice+reciprocal+restricted",
+			projects:       []string{
+				"firstparty",
+				"notice",
+				"reciprocal",
+				"restricted",
+			},
+			expectedStdout: "PASS -- parsed 4 project metadata files for 4 projects",
+		},
+		{
+			name:           "proprietary",
+			projects:       []string{"proprietary"},
+			expectedStdout: "PASS -- parsed 1 project metadata files for 1 projects",
+		},
+		{
+			name:           "1p+notice+reciprocal+restricted+proprietary",
+			projects:       []string{
+				"firstparty",
+				"notice",
+				"reciprocal",
+				"restricted",
+				"proprietary",
+			},
+			expectedStdout: "PASS -- parsed 5 project metadata files for 5 projects",
+		},
+		{
+			name:           "missing1",
+			projects:       []string{"regressgpl1"},
+			expectedStdout: "PASS -- parsed 0 project metadata files for 1 projects",
+		},
+		{
+			name:           "1p+notice+reciprocal+restricted+proprietary+missing1",
+			projects:       []string{
+				"firstparty",
+				"notice",
+				"reciprocal",
+				"restricted",
+				"proprietary",
+				"regressgpl1",
+			},
+			expectedStdout: "PASS -- parsed 5 project metadata files for 6 projects",
+		},
+		{
+			name:           "missing2",
+			projects:       []string{"regressgpl2"},
+			expectedStdout: "PASS -- parsed 0 project metadata files for 1 projects",
+		},
+		{
+			name:           "1p+notice+reciprocal+restricted+proprietary+missing1+missing2",
+			projects:       []string{
+				"firstparty",
+				"notice",
+				"reciprocal",
+				"restricted",
+				"proprietary",
+				"regressgpl1",
+				"regressgpl2",
+			},
+			expectedStdout: "PASS -- parsed 5 project metadata files for 7 projects",
+		},
+		{
+			name:           "missing2+1p+notice+reciprocal+restricted+proprietary+missing1",
+			projects:       []string{
+				"regressgpl2",
+				"firstparty",
+				"notice",
+				"reciprocal",
+				"restricted",
+				"proprietary",
+				"regressgpl1",
+			},
+			expectedStdout: "PASS -- parsed 5 project metadata files for 7 projects",
+		},
+		{
+			name:           "missing2+1p+notice+missing1+reciprocal+restricted+proprietary",
+			projects:       []string{
+				"regressgpl2",
+				"firstparty",
+				"notice",
+				"regressgpl1",
+				"reciprocal",
+				"restricted",
+				"proprietary",
+			},
+			expectedStdout: "PASS -- parsed 5 project metadata files for 7 projects",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			stdout := &bytes.Buffer{}
+			stderr := &bytes.Buffer{}
+
+			projects := make([]string, 0, len(tt.projects))
+			for _, project := range tt.projects {
+				projects = append(projects, "testdata/"+project)
+			}
+			err := checkProjectMetadata(stdout, stderr, compliance.GetFS(""), projects...)
+			if err != nil {
+				t.Fatalf("checkmetadata: error = %v, stderr = %v", err, stderr)
+				return
+			}
+			var actualStdout string
+			for _, s := range strings.Split(stdout.String(), "\n") {
+				ts := strings.TrimLeft(s, " \t")
+				if len(ts) < 1 {
+					continue
+				}
+				if len(actualStdout) > 0 {
+					t.Errorf("checkmetadata: unexpected multiple output lines %q, want %q", actualStdout+"\n"+ts, tt.expectedStdout)
+				}
+				actualStdout = ts
+			}
+			if actualStdout != tt.expectedStdout {
+				t.Errorf("checkmetadata: unexpected stdout %q, want %q", actualStdout, tt.expectedStdout)
+			}
+		})
+	}
+}
diff --git a/tools/compliance/cmd/testdata/firstparty/METADATA b/tools/compliance/cmd/testdata/firstparty/METADATA
new file mode 100644
index 0000000000..62b4481159
--- /dev/null
+++ b/tools/compliance/cmd/testdata/firstparty/METADATA
@@ -0,0 +1,6 @@
+# Comments are allowed
+name: "1ptd"
+description: "First Party Test Data"
+third_party {
+    version: "1.0"
+}
diff --git a/tools/compliance/cmd/testdata/notice/METADATA b/tools/compliance/cmd/testdata/notice/METADATA
new file mode 100644
index 0000000000..302dfeb54e
--- /dev/null
+++ b/tools/compliance/cmd/testdata/notice/METADATA
@@ -0,0 +1,6 @@
+# Comments are allowed
+name: "noticetd"
+description: "Notice Test Data"
+third_party {
+    version: "1.0"
+}
diff --git a/tools/compliance/cmd/testdata/proprietary/METADATA b/tools/compliance/cmd/testdata/proprietary/METADATA
new file mode 100644
index 0000000000..72cc54ab9b
--- /dev/null
+++ b/tools/compliance/cmd/testdata/proprietary/METADATA
@@ -0,0 +1 @@
+# comments are allowed
diff --git a/tools/compliance/cmd/testdata/reciprocal/METADATA b/tools/compliance/cmd/testdata/reciprocal/METADATA
new file mode 100644
index 0000000000..50cc2ef3ef
--- /dev/null
+++ b/tools/compliance/cmd/testdata/reciprocal/METADATA
@@ -0,0 +1,5 @@
+# Comments are allowed
+description: "Reciprocal Test Data"
+third_party {
+    version: "1.0"
+}
diff --git a/tools/compliance/cmd/testdata/restricted/METADATA b/tools/compliance/cmd/testdata/restricted/METADATA
new file mode 100644
index 0000000000..6bcf83f6bb
--- /dev/null
+++ b/tools/compliance/cmd/testdata/restricted/METADATA
@@ -0,0 +1,6 @@
+name {
+    id: 1
+}
+third_party {
+    version: 2
+}
diff --git a/tools/compliance/cmd/testdata/restricted/METADATA.android b/tools/compliance/cmd/testdata/restricted/METADATA.android
new file mode 100644
index 0000000000..1142499dee
--- /dev/null
+++ b/tools/compliance/cmd/testdata/restricted/METADATA.android
@@ -0,0 +1,6 @@
+# Comments are allowed
+name: "testdata"
+description: "Restricted Test Data"
+third_party {
+    version: "1.0"
+}
diff --git a/tools/compliance/policy_policy_test.go b/tools/compliance/policy_policy_test.go
index 94d0be332c..6188eb202d 100644
--- a/tools/compliance/policy_policy_test.go
+++ b/tools/compliance/policy_policy_test.go
@@ -20,6 +20,8 @@ import (
 	"sort"
 	"strings"
 	"testing"
+
+	"android/soong/tools/compliance/testfs"
 )
 
 func TestPolicy_edgeConditions(t *testing.T) {
@@ -210,7 +212,7 @@ func TestPolicy_edgeConditions(t *testing.T) {
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			fs := make(testFS)
+			fs := make(testfs.TestFS)
 			stderr := &bytes.Buffer{}
 			target := meta[tt.edge.target] + fmt.Sprintf("deps: {\n  file: \"%s\"\n", tt.edge.dep)
 			for _, ann := range tt.edge.annotations {
diff --git a/tools/compliance/projectmetadata/Android.bp b/tools/compliance/projectmetadata/Android.bp
new file mode 100644
index 0000000000..dccff7697f
--- /dev/null
+++ b/tools/compliance/projectmetadata/Android.bp
@@ -0,0 +1,34 @@
+// Copyright (C) 2022 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 {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
+bootstrap_go_package {
+    name: "projectmetadata-module",
+    srcs: [
+        "projectmetadata.go",
+    ],
+    deps: [
+        "compliance-test-fs-module",
+        "golang-protobuf-proto",
+        "golang-protobuf-encoding-prototext",
+        "project_metadata_proto",
+    ],
+    testSrcs: [
+        "projectmetadata_test.go",
+    ],
+    pkgPath: "android/soong/tools/compliance/projectmetadata",
+}
diff --git a/tools/compliance/projectmetadata/projectmetadata.go b/tools/compliance/projectmetadata/projectmetadata.go
new file mode 100644
index 0000000000..b31413d03a
--- /dev/null
+++ b/tools/compliance/projectmetadata/projectmetadata.go
@@ -0,0 +1,209 @@
+// Copyright 2022 Google LLC
+//
+// 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 projectmetadata
+
+import (
+	"fmt"
+	"io"
+	"io/fs"
+	"path/filepath"
+	"strings"
+	"sync"
+
+	"android/soong/compliance/project_metadata_proto"
+
+	"google.golang.org/protobuf/encoding/prototext"
+)
+
+var (
+	// ConcurrentReaders is the size of the task pool for limiting resource usage e.g. open files.
+	ConcurrentReaders = 5
+)
+
+// ProjectMetadata contains the METADATA for a git project.
+type ProjectMetadata struct {
+	proto project_metadata_proto.Metadata
+
+	// project is the path to the directory containing the METADATA file.
+	project string
+}
+
+// String returns a string representation of the metadata for error messages.
+func (pm *ProjectMetadata) String() string {
+	return fmt.Sprintf("project: %q\n%s", pm.project, pm.proto.String())
+}
+
+// VersionedName returns the name of the project including the version if any.
+func (pm *ProjectMetadata) VersionedName() string {
+	name := pm.proto.GetName()
+	if name != "" {
+		tp := pm.proto.GetThirdParty()
+		if tp != nil {
+			version := tp.GetVersion()
+			if version != "" {
+				if version[0] == 'v' || version[0] == 'V' {
+					return name + "_" + version
+				} else {
+					return name + "_v_" + version
+				}
+			}
+		}
+		return name
+	}
+	return pm.proto.GetDescription()
+}
+
+// projectIndex describes a project to be read; after `wg.Wait()`, will contain either
+// a `ProjectMetadata`, pm (can be nil even without error), or a non-nil `err`.
+type projectIndex struct {
+	project string
+	pm *ProjectMetadata
+	err error
+	done chan struct{}
+}
+
+// finish marks the task to read the `projectIndex` completed.
+func (pi *projectIndex) finish() {
+	close(pi.done)
+}
+
+// wait suspends execution until the `projectIndex` task completes.
+func (pi *projectIndex) wait() {
+	<-pi.done
+}
+
+// Index reads and caches ProjectMetadata (thread safe)
+type Index struct {
+	// projecs maps project name to a wait group if read has already started, and
+	// to a `ProjectMetadata` or to an `error` after the read completes.
+	projects sync.Map
+
+	// task provides a fixed-size task pool to limit concurrent open files etc.
+	task chan bool
+
+	// rootFS locates the root of the file system from which to read the files.
+	rootFS fs.FS
+}
+
+// NewIndex constructs a project metadata `Index` for the given file system.
+func NewIndex(rootFS fs.FS) *Index {
+	ix := &Index{task: make(chan bool, ConcurrentReaders), rootFS: rootFS}
+	for i := 0; i < ConcurrentReaders; i++ {
+		ix.task <- true
+	}
+	return ix
+}
+
+// MetadataForProjects returns 0..n ProjectMetadata for n `projects`, or an error.
+// Each project that has a METADATA.android or a METADATA file in the root of the project will have
+// a corresponding ProjectMetadata in the result. Projects with neither file get skipped. A nil
+// result with no error indicates none of the given `projects` has a METADATA file.
+// (thread safe -- can be called concurrently from multiple goroutines)
+func (ix *Index) MetadataForProjects(projects ...string) ([]*ProjectMetadata, error) {
+	if ConcurrentReaders < 1 {
+		return nil, fmt.Errorf("need at least one task in project metadata pool")
+	}
+	if len(projects) == 0 {
+		return nil, nil
+	}
+	// Identify the projects that have never been read
+	projectsToRead := make([]*projectIndex, 0, len(projects))
+	projectIndexes := make([]*projectIndex, 0, len(projects))
+	for _, p := range projects {
+		pi, loaded := ix.projects.LoadOrStore(p, &projectIndex{project: p, done: make(chan struct{})})
+		if !loaded {
+			projectsToRead = append(projectsToRead, pi.(*projectIndex))
+		}
+		projectIndexes = append(projectIndexes, pi.(*projectIndex))
+	}
+	// findMeta locates and reads the appropriate METADATA file, if any.
+	findMeta := func(pi *projectIndex) {
+		<-ix.task
+		defer func() {
+			ix.task <- true
+			pi.finish()
+		}()
+
+		// Support METADATA.android for projects that already have a different sort of METADATA file.
+		path := filepath.Join(pi.project, "METADATA.android")
+		fi, err := fs.Stat(ix.rootFS, path)
+		if err == nil {
+			if fi.Mode().IsRegular() {
+				ix.readMetadataFile(pi, path)
+				return
+			}
+		}
+		// No METADATA.android try METADATA file.
+		path = filepath.Join(pi.project, "METADATA")
+		fi, err = fs.Stat(ix.rootFS, path)
+		if err == nil {
+			if fi.Mode().IsRegular() {
+				ix.readMetadataFile(pi, path)
+				return
+			}
+		}
+		// no METADATA file exists -- leave nil and finish
+	}
+	// Look for the METADATA files to read, and record any missing.
+	for _, p := range projectsToRead {
+		go findMeta(p)
+	}
+	// Wait until all of the projects have been read.
+	var msg strings.Builder
+	result := make([]*ProjectMetadata, 0, len(projects))
+	for _, pi := range projectIndexes {
+		pi.wait()
+		// Combine any errors into a single error.
+		if pi.err != nil {
+			fmt.Fprintf(&msg, "  %v\n", pi.err)
+		} else if pi.pm != nil {
+			result = append(result, pi.pm)
+		}
+	}
+	if msg.Len() > 0 {
+		return nil, fmt.Errorf("error reading project(s):\n%s", msg.String())
+	}
+	if len(result) == 0 {
+		return nil, nil
+	}
+	return result, nil
+}
+
+// readMetadataFile tries to read and parse a METADATA file at `path` for `project`.
+func (ix *Index) readMetadataFile(pi *projectIndex, path string) {
+	f, err := ix.rootFS.Open(path)
+	if err != nil {
+		pi.err = fmt.Errorf("error opening project %q metadata %q: %w", pi.project, path, err)
+		return
+	}
+
+	// read the file
+	data, err := io.ReadAll(f)
+	if err != nil {
+		pi.err = fmt.Errorf("error reading project %q metadata %q: %w", pi.project, path, err)
+		return
+	}
+	f.Close()
+
+	uo := prototext.UnmarshalOptions{DiscardUnknown: true}
+	pm := &ProjectMetadata{project: pi.project}
+	err = uo.Unmarshal(data, &pm.proto)
+	if err != nil {
+		pi.err = fmt.Errorf("error in project %q metadata %q: %w", pi.project, path, err)
+		return
+	}
+
+	pi.pm = pm
+}
diff --git a/tools/compliance/projectmetadata/projectmetadata_test.go b/tools/compliance/projectmetadata/projectmetadata_test.go
new file mode 100644
index 0000000000..1e4256ff5f
--- /dev/null
+++ b/tools/compliance/projectmetadata/projectmetadata_test.go
@@ -0,0 +1,294 @@
+// Copyright 2022 Google LLC
+//
+// 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 projectmetadata
+
+import (
+	"fmt"
+	"strings"
+	"testing"
+
+	"android/soong/tools/compliance/testfs"
+)
+
+const (
+	// EMPTY represents a METADATA file with no recognized fields
+	EMPTY = ``
+
+	// INVALID_NAME represents a METADATA file with the wrong type of name
+	INVALID_NAME = `name: a library\n`
+
+	// INVALID_DESCRIPTION represents a METADATA file with the wrong type of description
+	INVALID_DESCRIPTION = `description: unquoted text\n`
+
+	// INVALID_VERSION represents a METADATA file with the wrong type of version
+	INVALID_VERSION = `third_party { version: 1 }`
+
+	// MY_LIB_1_0 represents a METADATA file for version 1.0 of mylib
+	MY_LIB_1_0 = `name: "mylib" description: "my library" third_party { version: "1.0" }`
+
+	// NO_NAME_0_1 represents a METADATA file with a description but no name
+	NO_NAME_0_1 = `description: "my library" third_party { version: "0.1" }`
+)
+
+func TestReadMetadataForProjects(t *testing.T) {
+	tests := []struct {
+		name          string
+		fs            *testfs.TestFS
+		projects      []string
+		expectedError string
+		expected      []pmeta
+	}{
+		{
+			name: "trivial",
+			fs: &testfs.TestFS{
+				"/a/METADATA": []byte("name: \"Android\"\n"),
+			},
+			projects: []string{"/a"},
+			expected: []pmeta{{project: "/a", versionedName: "Android"}},
+		},
+		{
+			name: "versioned",
+			fs: &testfs.TestFS{
+				"/a/METADATA": []byte(MY_LIB_1_0),
+			},
+			projects: []string{"/a"},
+			expected: []pmeta{{project: "/a", versionedName: "mylib_v_1.0"}},
+		},
+		{
+			name: "versioneddesc",
+			fs: &testfs.TestFS{
+				"/a/METADATA": []byte(NO_NAME_0_1),
+			},
+			projects: []string{"/a"},
+			expected: []pmeta{{project: "/a", versionedName: "my library"}},
+		},
+		{
+			name: "unterminated",
+			fs: &testfs.TestFS{
+				"/a/METADATA": []byte("name: \"Android\n"),
+			},
+			projects:      []string{"/a"},
+			expectedError: `invalid character '\n' in string`,
+		},
+		{
+			name: "abc",
+			fs: &testfs.TestFS{
+				"/a/METADATA": []byte(EMPTY),
+				"/b/METADATA": []byte(MY_LIB_1_0),
+				"/c/METADATA": []byte(NO_NAME_0_1),
+			},
+			projects: []string{"/a", "/b", "/c"},
+			expected: []pmeta{
+				{project: "/a", versionedName: ""},
+				{project: "/b", versionedName: "mylib_v_1.0"},
+				{project: "/c", versionedName: "my library"},
+			},
+		},
+		{
+			name: "ab",
+			fs: &testfs.TestFS{
+				"/a/METADATA": []byte(EMPTY),
+				"/b/METADATA": []byte(MY_LIB_1_0),
+			},
+			projects: []string{"/a", "/b", "/c"},
+			expected: []pmeta{
+				{project: "/a", versionedName: ""},
+				{project: "/b", versionedName: "mylib_v_1.0"},
+			},
+		},
+		{
+			name: "ac",
+			fs: &testfs.TestFS{
+				"/a/METADATA": []byte(EMPTY),
+				"/c/METADATA": []byte(NO_NAME_0_1),
+			},
+			projects: []string{"/a", "/b", "/c"},
+			expected: []pmeta{
+				{project: "/a", versionedName: ""},
+				{project: "/c", versionedName: "my library"},
+			},
+		},
+		{
+			name: "bc",
+			fs: &testfs.TestFS{
+				"/b/METADATA": []byte(MY_LIB_1_0),
+				"/c/METADATA": []byte(NO_NAME_0_1),
+			},
+			projects: []string{"/a", "/b", "/c"},
+			expected: []pmeta{
+				{project: "/b", versionedName: "mylib_v_1.0"},
+				{project: "/c", versionedName: "my library"},
+			},
+		},
+		{
+			name: "wrongnametype",
+			fs: &testfs.TestFS{
+				"/a/METADATA": []byte(INVALID_NAME),
+			},
+			projects:      []string{"/a"},
+			expectedError: `invalid value for string type`,
+		},
+		{
+			name: "wrongdescriptiontype",
+			fs: &testfs.TestFS{
+				"/a/METADATA": []byte(INVALID_DESCRIPTION),
+			},
+			projects:      []string{"/a"},
+			expectedError: `invalid value for string type`,
+		},
+		{
+			name: "wrongversiontype",
+			fs: &testfs.TestFS{
+				"/a/METADATA": []byte(INVALID_VERSION),
+			},
+			projects:      []string{"/a"},
+			expectedError: `invalid value for string type`,
+		},
+		{
+			name: "wrongtype",
+			fs: &testfs.TestFS{
+				"/a/METADATA": []byte(INVALID_NAME + INVALID_DESCRIPTION + INVALID_VERSION),
+			},
+			projects:      []string{"/a"},
+			expectedError: `invalid value for string type`,
+		},
+		{
+			name: "empty",
+			fs: &testfs.TestFS{
+				"/a/METADATA": []byte(EMPTY),
+			},
+			projects: []string{"/a"},
+			expected: []pmeta{{project: "/a", versionedName: ""}},
+		},
+		{
+			name: "emptyother",
+			fs: &testfs.TestFS{
+				"/a/METADATA.bp": []byte(EMPTY),
+			},
+			projects: []string{"/a"},
+		},
+		{
+			name:     "emptyfs",
+			fs:       &testfs.TestFS{},
+			projects: []string{"/a"},
+		},
+		{
+			name: "override",
+			fs: &testfs.TestFS{
+				"/a/METADATA":         []byte(INVALID_NAME + INVALID_DESCRIPTION + INVALID_VERSION),
+				"/a/METADATA.android": []byte(MY_LIB_1_0),
+			},
+			projects: []string{"/a"},
+			expected: []pmeta{{project: "/a", versionedName: "mylib_v_1.0"}},
+		},
+		{
+			name: "enchilada",
+			fs: &testfs.TestFS{
+				"/a/METADATA":         []byte(INVALID_NAME + INVALID_DESCRIPTION + INVALID_VERSION),
+				"/a/METADATA.android": []byte(EMPTY),
+				"/b/METADATA":         []byte(MY_LIB_1_0),
+				"/c/METADATA":         []byte(NO_NAME_0_1),
+			},
+			projects: []string{"/a", "/b", "/c"},
+			expected: []pmeta{
+				{project: "/a", versionedName: ""},
+				{project: "/b", versionedName: "mylib_v_1.0"},
+				{project: "/c", versionedName: "my library"},
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			ix := NewIndex(tt.fs)
+			pms, err := ix.MetadataForProjects(tt.projects...)
+			if err != nil {
+				if len(tt.expectedError) == 0 {
+					t.Errorf("unexpected error: got %s, want no error", err)
+				} else if !strings.Contains(err.Error(), tt.expectedError) {
+					t.Errorf("unexpected error: got %s, want %q", err, tt.expectedError)
+				}
+				return
+			}
+			t.Logf("actual %d project metadata", len(pms))
+			for _, pm := range pms {
+				t.Logf("  %v", pm.String())
+			}
+			t.Logf("expected %d project metadata", len(tt.expected))
+			for _, pm := range tt.expected {
+				t.Logf("  %s", pm.String())
+			}
+			if len(tt.expectedError) > 0 {
+				t.Errorf("unexpected success: got no error, want %q err", tt.expectedError)
+				return
+			}
+			if len(pms) != len(tt.expected) {
+				t.Errorf("missing project metadata: got %d project metadata, want %d", len(pms), len(tt.expected))
+			}
+			for i := 0; i < len(pms) && i < len(tt.expected); i++ {
+				if msg := tt.expected[i].difference(pms[i]); msg != "" {
+					t.Errorf("unexpected metadata starting at index %d: %s", i, msg)
+					return
+				}
+			}
+			if len(pms) < len(tt.expected) {
+				t.Errorf("missing metadata starting at index %d: got nothing, want %s", len(pms), tt.expected[len(pms)].String())
+			}
+			if len(tt.expected) < len(pms) {
+				t.Errorf("unexpected metadata starting at index %d: got %s, want nothing", len(tt.expected), pms[len(tt.expected)].String())
+			}
+		})
+	}
+}
+
+type pmeta struct {
+	project       string
+	versionedName string
+}
+
+func (pm pmeta) String() string {
+	return fmt.Sprintf("project: %q versionedName: %q\n", pm.project, pm.versionedName)
+}
+
+func (pm pmeta) equals(other *ProjectMetadata) bool {
+	if pm.project != other.project {
+		return false
+	}
+	if pm.versionedName != other.VersionedName() {
+		return false
+	}
+	return true
+}
+
+func (pm pmeta) difference(other *ProjectMetadata) string {
+	if pm.equals(other) {
+		return ""
+	}
+	var sb strings.Builder
+	fmt.Fprintf(&sb, "got")
+	if pm.project != other.project {
+		fmt.Fprintf(&sb, " project: %q", other.project)
+	}
+	if pm.versionedName != other.VersionedName() {
+		fmt.Fprintf(&sb, " versionedName: %q", other.VersionedName())
+	}
+	fmt.Fprintf(&sb, ", want")
+	if pm.project != other.project {
+		fmt.Fprintf(&sb, " project: %q", pm.project)
+	}
+	if pm.versionedName != other.VersionedName() {
+		fmt.Fprintf(&sb, " versionedName: %q", pm.versionedName)
+	}
+	return sb.String()
+}
diff --git a/tools/compliance/readgraph.go b/tools/compliance/readgraph.go
index 7faca86cde..bf364e66cd 100644
--- a/tools/compliance/readgraph.go
+++ b/tools/compliance/readgraph.go
@@ -34,10 +34,17 @@ var (
 
 type globalFS struct{}
 
+var _ fs.FS = globalFS{}
+var _ fs.StatFS = globalFS{}
+
 func (s globalFS) Open(name string) (fs.File, error) {
 	return os.Open(name)
 }
 
+func (s globalFS) Stat(name string) (fs.FileInfo, error) {
+	return os.Stat(name)
+}
+
 var FS globalFS
 
 // GetFS returns a filesystem for accessing files under the OUT_DIR environment variable.
diff --git a/tools/compliance/readgraph_test.go b/tools/compliance/readgraph_test.go
index bcf9f39603..a2fb04db4c 100644
--- a/tools/compliance/readgraph_test.go
+++ b/tools/compliance/readgraph_test.go
@@ -19,12 +19,14 @@ import (
 	"sort"
 	"strings"
 	"testing"
+
+	"android/soong/tools/compliance/testfs"
 )
 
 func TestReadLicenseGraph(t *testing.T) {
 	tests := []struct {
 		name            string
-		fs              *testFS
+		fs              *testfs.TestFS
 		roots           []string
 		expectedError   string
 		expectedEdges   []edge
@@ -32,7 +34,7 @@ func TestReadLicenseGraph(t *testing.T) {
 	}{
 		{
 			name: "trivial",
-			fs: &testFS{
+			fs: &testfs.TestFS{
 				"app.meta_lic": []byte("package_name: \"Android\"\n"),
 			},
 			roots:           []string{"app.meta_lic"},
@@ -41,7 +43,7 @@ func TestReadLicenseGraph(t *testing.T) {
 		},
 		{
 			name: "unterminated",
-			fs: &testFS{
+			fs: &testfs.TestFS{
 				"app.meta_lic": []byte("package_name: \"Android\n"),
 			},
 			roots:         []string{"app.meta_lic"},
@@ -49,7 +51,7 @@ func TestReadLicenseGraph(t *testing.T) {
 		},
 		{
 			name: "danglingref",
-			fs: &testFS{
+			fs: &testfs.TestFS{
 				"app.meta_lic": []byte(AOSP + "deps: {\n  file: \"lib.meta_lic\"\n}\n"),
 			},
 			roots:         []string{"app.meta_lic"},
@@ -57,7 +59,7 @@ func TestReadLicenseGraph(t *testing.T) {
 		},
 		{
 			name: "singleedge",
-			fs: &testFS{
+			fs: &testfs.TestFS{
 				"app.meta_lic": []byte(AOSP + "deps: {\n  file: \"lib.meta_lic\"\n}\n"),
 				"lib.meta_lic": []byte(AOSP),
 			},
@@ -67,7 +69,7 @@ func TestReadLicenseGraph(t *testing.T) {
 		},
 		{
 			name: "fullgraph",
-			fs: &testFS{
+			fs: &testfs.TestFS{
 				"apex.meta_lic": []byte(AOSP + "deps: {\n  file: \"app.meta_lic\"\n}\ndeps: {\n  file: \"bin.meta_lic\"\n}\n"),
 				"app.meta_lic":  []byte(AOSP),
 				"bin.meta_lic":  []byte(AOSP + "deps: {\n  file: \"lib.meta_lic\"\n}\n"),
diff --git a/tools/compliance/test_util.go b/tools/compliance/test_util.go
index c9d6fe29ec..6c50d3e761 100644
--- a/tools/compliance/test_util.go
+++ b/tools/compliance/test_util.go
@@ -17,10 +17,11 @@ package compliance
 import (
 	"fmt"
 	"io"
-	"io/fs"
 	"sort"
 	"strings"
 	"testing"
+
+	"android/soong/tools/compliance/testfs"
 )
 
 const (
@@ -145,51 +146,6 @@ func newTestConditionSet(lg *LicenseGraph, targetName string, conditionName []st
 	return cs
 }
 
-// testFS implements a test file system (fs.FS) simulated by a map from filename to []byte content.
-type testFS map[string][]byte
-
-// Open implements fs.FS.Open() to open a file based on the filename.
-func (fs *testFS) Open(name string) (fs.File, error) {
-	if _, ok := (*fs)[name]; !ok {
-		return nil, fmt.Errorf("unknown file %q", name)
-	}
-	return &testFile{fs, name, 0}, nil
-}
-
-// testFile implements a test file (fs.File) based on testFS above.
-type testFile struct {
-	fs   *testFS
-	name string
-	posn int
-}
-
-// Stat not implemented to obviate implementing fs.FileInfo.
-func (f *testFile) Stat() (fs.FileInfo, error) {
-	return nil, fmt.Errorf("unimplemented")
-}
-
-// Read copies bytes from the testFS map.
-func (f *testFile) Read(b []byte) (int, error) {
-	if f.posn < 0 {
-		return 0, fmt.Errorf("file not open: %q", f.name)
-	}
-	if f.posn >= len((*f.fs)[f.name]) {
-		return 0, io.EOF
-	}
-	n := copy(b, (*f.fs)[f.name][f.posn:])
-	f.posn += n
-	return n, nil
-}
-
-// Close marks the testFile as no longer in use.
-func (f *testFile) Close() error {
-	if f.posn < 0 {
-		return fmt.Errorf("file already closed: %q", f.name)
-	}
-	f.posn = -1
-	return nil
-}
-
 // edge describes test data edges to define test graphs.
 type edge struct {
 	target, dep string
@@ -268,7 +224,7 @@ func toGraph(stderr io.Writer, roots []string, edges []annotated) (*LicenseGraph
 			deps[edge.dep] = []annotated{}
 		}
 	}
-	fs := make(testFS)
+	fs := make(testfs.TestFS)
 	for file, edges := range deps {
 		body := meta[file]
 		for _, edge := range edges {
diff --git a/tools/compliance/testfs/Android.bp b/tools/compliance/testfs/Android.bp
new file mode 100644
index 0000000000..6baaf18b66
--- /dev/null
+++ b/tools/compliance/testfs/Android.bp
@@ -0,0 +1,25 @@
+// Copyright (C) 2022 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 {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
+bootstrap_go_package {
+    name: "compliance-test-fs-module",
+    srcs: [
+        "testfs.go",
+    ],
+    pkgPath: "android/soong/tools/compliance/testfs",
+}
diff --git a/tools/compliance/testfs/testfs.go b/tools/compliance/testfs/testfs.go
new file mode 100644
index 0000000000..2c75c5b1d7
--- /dev/null
+++ b/tools/compliance/testfs/testfs.go
@@ -0,0 +1,129 @@
+// Copyright 2022 Google LLC
+//
+// 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 testfs
+
+import (
+	"fmt"
+	"io"
+	"io/fs"
+	"strings"
+	"time"
+)
+
+// TestFS implements a test file system (fs.FS) simulated by a map from filename to []byte content.
+type TestFS map[string][]byte
+
+var _ fs.FS = (*TestFS)(nil)
+var _ fs.StatFS = (*TestFS)(nil)
+
+// Open implements fs.FS.Open() to open a file based on the filename.
+func (tfs *TestFS) Open(name string) (fs.File, error) {
+	if _, ok := (*tfs)[name]; !ok {
+		return nil, fmt.Errorf("unknown file %q", name)
+	}
+	return &TestFile{tfs, name, 0}, nil
+}
+
+// Stat implements fs.StatFS.Stat() to examine a file based on the filename.
+func (tfs *TestFS) Stat(name string) (fs.FileInfo, error) {
+	if content, ok := (*tfs)[name]; ok {
+		return &TestFileInfo{name, len(content), 0666}, nil
+	}
+	dirname := name
+	if !strings.HasSuffix(dirname, "/") {
+		dirname = dirname + "/"
+	}
+	for name := range (*tfs) {
+		if strings.HasPrefix(name, dirname) {
+			return &TestFileInfo{name, 8, fs.ModeDir | fs.ModePerm}, nil
+		}
+	}
+	return nil, fmt.Errorf("file not found: %q", name)
+}
+
+// TestFileInfo implements a file info (fs.FileInfo) based on TestFS above.
+type TestFileInfo struct {
+	name string
+	size int
+	mode fs.FileMode
+}
+
+var _ fs.FileInfo = (*TestFileInfo)(nil)
+
+// Name returns the name of the file
+func (fi *TestFileInfo) Name() string {
+	return fi.name
+}
+
+// Size returns the size of the file in bytes.
+func (fi *TestFileInfo) Size() int64 {
+	return int64(fi.size)
+}
+
+// Mode returns the fs.FileMode bits.
+func (fi *TestFileInfo) Mode() fs.FileMode {
+	return fi.mode
+}
+
+// ModTime fakes a modification time.
+func (fi *TestFileInfo) ModTime() time.Time {
+	return time.UnixMicro(0xb0bb)
+}
+
+// IsDir is a synonym for Mode().IsDir()
+func (fi *TestFileInfo) IsDir() bool {
+	return fi.mode.IsDir()
+}
+
+// Sys is unused and returns nil.
+func (fi *TestFileInfo) Sys() any {
+	return nil
+}
+
+// TestFile implements a test file (fs.File) based on TestFS above.
+type TestFile struct {
+	fs   *TestFS
+	name string
+	posn int
+}
+
+var _ fs.File = (*TestFile)(nil)
+
+// Stat not implemented to obviate implementing fs.FileInfo.
+func (f *TestFile) Stat() (fs.FileInfo, error) {
+	return f.fs.Stat(f.name)
+}
+
+// Read copies bytes from the TestFS map.
+func (f *TestFile) Read(b []byte) (int, error) {
+	if f.posn < 0 {
+		return 0, fmt.Errorf("file not open: %q", f.name)
+	}
+	if f.posn >= len((*f.fs)[f.name]) {
+		return 0, io.EOF
+	}
+	n := copy(b, (*f.fs)[f.name][f.posn:])
+	f.posn += n
+	return n, nil
+}
+
+// Close marks the TestFile as no longer in use.
+func (f *TestFile) Close() error {
+	if f.posn < 0 {
+		return fmt.Errorf("file already closed: %q", f.name)
+	}
+	f.posn = -1
+	return nil
+}