internal: add GetLicenses by path

This change introduces a new method on the DataSource interface,
GetLicenses, which returns the licenses that apply for a given path,
module path, and resolved version combination.
A license in the current or any parent directory of the specified path
applies to it.

Fixes golang/go#40027

Change-Id: If91429ac12880ac3b6254bf0acd7d3ac983c93e7
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/241718
Reviewed-by: Julie Qiu <julie@golang.org>

internal/datasource.go

@@ -21,6 +21,8 @@ type DataSource interface {
 	// GetImports returns a slice of import paths imported by the package
 	// specified by path and version.
 	GetImports(ctx context.Context, pkgPath, modulePath, version string) ([]string, error)
+	// GetLicenses returns licenses at the given path for given modulePath and version.
+	GetLicenses(ctx context.Context, fullPath, modulePath, resolvedVersion string) ([]*licenses.License, error)
 	// GetModuleInfo returns the ModuleInfo corresponding to modulePath and
 	// version.
 	GetModuleInfo(ctx context.Context, modulePath, version string) (*ModuleInfo, error)

internal/postgres/licenses.go

@@ -8,6 +8,7 @@ import (
 	"context"
 	"database/sql"
 	"fmt"
+	"path"
 	"reflect"
 	"sort"
 	"strings"
@@ -17,6 +18,61 @@ import (
 	"golang.org/x/pkgsite/internal/licenses"
 )
 
+// GetLicenses returns the licenses that applies to the fullPath for the given module version.
+// It returns an InvalidArgument error if the module path or version is invalid.
+func (db *DB) GetLicenses(ctx context.Context, fullPath, modulePath, resolvedVersion string) (_ []*licenses.License, err error) {
+	defer derrors.Wrap(&err, "GetLicenses(ctx, %q, %q, %q)", fullPath, modulePath, resolvedVersion)
+
+	if fullPath == "" || resolvedVersion == "" {
+		return nil, fmt.Errorf("neither fullpath nor resolvedVersion can be empty: %w", derrors.InvalidArgument)
+	}
+	query := `
+		SELECT
+			l.types,
+			l.file_path,
+			l.contents,
+			l.coverage
+		FROM
+			licenses l
+		INNER JOIN
+			paths p
+		ON
+			p.module_id=l.module_id
+		INNER JOIN
+			modules m
+		ON
+			p.module_id=m.id
+		WHERE
+			p.path = $1
+			AND m.module_path = $2
+			AND m.version = $3;`
+
+	rows, err := db.db.Query(ctx, query, fullPath, modulePath, resolvedVersion)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	moduleLicenses, err := collectLicenses(rows)
+	if err != nil {
+		return nil, err
+	}
+
+	var lics []*licenses.License
+
+	// The `query` returns all licenses for the module version. We need to
+	// filter the licenses that applies to the specified fullPath, i.e.
+	// A license in the current or any parent directory of the specified
+	// fullPath applies to it.
+	for _, license := range moduleLicenses {
+		licensePath := path.Join(modulePath, path.Dir(license.FilePath))
+		if strings.HasPrefix(fullPath, licensePath) {
+			lics = append(lics, license)
+		}
+	}
+	return lics, nil
+}
+
 // LegacyGetModuleLicenses returns all licenses associated with the given module path and
 // version. These are the top-level licenses in the module zip file.
 // It returns an InvalidArgument error if the module path or version is invalid.

internal/postgres/licenses_test.go

@@ -6,13 +6,83 @@ package postgres
 
 import (
 	"context"
+	"errors"
+	"sort"
 	"testing"
 
 	"github.com/google/go-cmp/cmp"
+	"github.com/google/go-cmp/cmp/cmpopts"
+	"golang.org/x/pkgsite/internal/derrors"
 	"golang.org/x/pkgsite/internal/licenses"
 	"golang.org/x/pkgsite/internal/testing/sample"
 )
 
+func TestGetLicenses(t *testing.T) {
+	testModule := sample.Module(sample.ModulePath, "v1.2.3", "A/B")
+	mit := &licenses.Metadata{Types: []string{"MIT"}, FilePath: "LICENSE"}
+	bsd := &licenses.Metadata{Types: []string{"BSD-3-Clause"}, FilePath: "A/B/LICENSE"}
+
+	mitLicense := &licenses.License{Metadata: mit}
+	bsdLicense := &licenses.License{Metadata: bsd}
+	testModule.Licenses = []*licenses.License{bsdLicense, mitLicense}
+	sort.Slice(testModule.Directories, func(i, j int) bool {
+		return testModule.Directories[i].Path < testModule.Directories[j].Path
+	})
+
+	// github.com/valid/module_name
+	testModule.Directories[0].Licenses = []*licenses.Metadata{mit}
+	// github.com/valid/module_name/A
+	testModule.Directories[1].Licenses = []*licenses.Metadata{mit}
+	// github.com/valid/module_name/A/B
+	testModule.Directories[2].Licenses = []*licenses.Metadata{mit, bsd}
+
+	tests := []struct {
+		err      error
+		name     string
+		fullPath string
+		want     []*licenses.License
+	}{
+		{name: "empty path", err: derrors.InvalidArgument},
+		{name: "module root", fullPath: sample.ModulePath, want: []*licenses.License{testModule.Licenses[1]}},
+		{name: "package without license", fullPath: sample.ModulePath + "/A", want: []*licenses.License{testModule.Licenses[1]}},
+		{name: "package with additional license", fullPath: sample.ModulePath + "/A/B", want: testModule.Licenses},
+	}
+
+	defer ResetTestDB(testDB, t)
+	ctx, cancel := context.WithTimeout(context.Background(), testTimeout*5)
+	defer cancel()
+	if err := testDB.InsertModule(ctx, testModule); err != nil {
+		t.Fatal(err)
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			got, err := testDB.GetLicenses(ctx, test.fullPath, sample.ModulePath, testModule.Version)
+			if !errors.Is(err, test.err) {
+				t.Fatal(err)
+			}
+
+			sort.Slice(got, func(i, j int) bool {
+				return got[i].FilePath < got[j].FilePath
+			})
+			sort.Slice(test.want, func(i, j int) bool {
+				return test.want[i].FilePath < test.want[j].FilePath
+			})
+			for i := range got {
+				sort.Strings(got[i].Types)
+			}
+			for i := range test.want {
+				sort.Strings(test.want[i].Types)
+			}
+
+			cmpopt := cmpopts.IgnoreFields(licenses.License{}, "Contents")
+			if diff := cmp.Diff(test.want, got, cmpopt); diff != "" {
+				t.Errorf("mismatch (-want +got):\n%s", diff)
+			}
+		})
+	}
+}
+
 func TestLegacyGetModuleLicenses(t *testing.T) {
 	modulePath := "test.module"
 	testModule := sample.Module(modulePath, "v1.2.3", "", "foo", "bar")

internal/proxydatasource/datasource.go

@@ -117,6 +117,33 @@ func (ds *DataSource) GetImports(ctx context.Context, pkgPath, modulePath, versi
 	return vp.Imports, nil
 }
 
+// GetLicenses return licenses at path for the given module path and version.
+func (ds *DataSource) GetLicenses(ctx context.Context, fullPath, modulePath, resolvedVersion string) (_ []*licenses.License, err error) {
+	defer derrors.Wrap(&err, "GetLicenses(%q, %q, %q)", fullPath, modulePath, resolvedVersion)
+	v, err := ds.getModule(ctx, modulePath, resolvedVersion)
+	if err != nil {
+		return nil, err
+	}
+
+	var lics []*licenses.License
+
+	// ds.getModule() returns all licenses for the module version. We need to
+	// filter the licenses that applies to the specified fullPath, i.e.
+	// A license in the current or any parent directory of the specified
+	// fullPath applies to it.
+	for _, license := range v.Licenses {
+		licensePath := path.Join(modulePath, path.Dir(license.FilePath))
+		if strings.HasPrefix(fullPath, licensePath) {
+			lics = append(lics, license)
+		}
+	}
+
+	if len(lics) == 0 {
+		return nil, fmt.Errorf("path %s is missing from module %s: %w", fullPath, modulePath, derrors.NotFound)
+	}
+	return lics, nil
+}
+
 // LegacyGetModuleLicenses returns root-level licenses detected within the module zip
 // for modulePath and version.
 func (ds *DataSource) LegacyGetModuleLicenses(ctx context.Context, modulePath, version string) (_ []*licenses.License, err error) {

internal/proxydatasource/datasource_test.go

@@ -6,12 +6,16 @@ package proxydatasource
 
 import (
 	"context"
+	"errors"
+	"sort"
 	"testing"
 	"time"
 
 	"github.com/google/go-cmp/cmp"
 	"github.com/google/go-cmp/cmp/cmpopts"
+	"github.com/google/licensecheck"
 	"golang.org/x/pkgsite/internal"
+	"golang.org/x/pkgsite/internal/derrors"
 	"golang.org/x/pkgsite/internal/licenses"
 	"golang.org/x/pkgsite/internal/proxy"
 	"golang.org/x/pkgsite/internal/testing/sample"
@@ -49,6 +53,28 @@ func setup(t *testing.T) (context.Context, *DataSource, func()) {
 var (
 	wantLicenseMD  = sample.LicenseMetadata[0]
 	wantLicense    = &licenses.License{Metadata: wantLicenseMD}
+	wantLicenseMIT = &licenses.License{
+		Metadata: &licenses.Metadata{
+			Types:    []string{"MIT"},
+			FilePath: "LICENSE",
+			Coverage: licensecheck.Coverage{
+				Percent: 100,
+				Match:   []licensecheck.Match{{Name: "MIT", Type: licensecheck.MIT, Percent: 100, End: 1049}},
+			},
+		},
+		Contents: []byte(testhelper.MITLicense),
+	}
+	wantLicenseBSD = &licenses.License{
+		Metadata: &licenses.Metadata{
+			Types:    []string{"BSD-0-Clause"},
+			FilePath: "qux/LICENSE",
+			Coverage: licensecheck.Coverage{
+				Percent: 100,
+				Match:   []licensecheck.Match{{Name: "BSD-0-Clause", Type: licensecheck.BSD, Percent: 100, End: 633}},
+			},
+		},
+		Contents: []byte(testhelper.BSD0License),
+	}
 	wantPackage = internal.LegacyPackage{
 		Path:              "foo.com/bar/baz",
 		Name:              "baz",
@@ -144,6 +170,68 @@ func TestDataSource_GetModuleInfo(t *testing.T) {
 	}
 }
 
+func TestDataSource_GetLicenses(t *testing.T) {
+	t.Helper()
+	testModules := []*proxy.TestModule{
+		{
+			ModulePath: "foo.com/bar",
+			Version:    "v1.1.0",
+			Files: map[string]string{
+				"go.mod":  "module foo.com/bar",
+				"LICENSE": testhelper.MITLicense,
+				"bar.go":  "//Package bar provides a helpful constant.\npackage bar\nimport \"net/http\"\nconst OK = http.StatusOK",
+
+				"baz/baz.go": "//Package baz provides a helpful constant.\npackage baz\nimport \"net/http\"\nconst OK = http.StatusOK",
+
+				"qux/LICENSE": testhelper.BSD0License,
+				"qux/qux.go":  "//Package qux provides a helpful constant.\npackage qux\nimport \"net/http\"\nconst OK = http.StatusOK",
+			},
+		},
+	}
+	client, teardownProxy := proxy.SetupTestProxy(t, testModules)
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	ds := New(client)
+	teardown := func() {
+		teardownProxy()
+		cancel()
+	}
+	defer teardown()
+
+	tests := []struct {
+		err        error
+		name       string
+		fullPath   string
+		modulePath string
+		want       []*licenses.License
+	}{
+		{name: "no license dir", fullPath: "foo.com", modulePath: "foo.com/bar", err: derrors.NotFound},
+		{name: "invalid dir", fullPath: "foo.com/invalid", modulePath: "foo.com/invalid", err: derrors.NotFound},
+		{name: "root dir", fullPath: "foo.com/bar", modulePath: "foo.com/bar", want: []*licenses.License{wantLicenseMIT}},
+		{name: "package with no extra license", fullPath: "foo.com/bar/baz", modulePath: "foo.com/bar", want: []*licenses.License{wantLicenseMIT}},
+		{name: "package with additional license", fullPath: "foo.com/bar/qux", modulePath: "foo.com/bar", want: []*licenses.License{wantLicenseMIT, wantLicenseBSD}},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			got, err := ds.GetLicenses(ctx, test.fullPath, test.modulePath, "v1.1.0")
+			if !errors.Is(err, test.err) {
+				t.Fatal(err)
+			}
+
+			sort.Slice(got, func(i, j int) bool {
+				return got[i].FilePath < got[j].FilePath
+			})
+			sort.Slice(test.want, func(i, j int) bool {
+				return test.want[i].FilePath < test.want[j].FilePath
+			})
+
+			if diff := cmp.Diff(test.want, got); diff != "" {
+				t.Errorf("GetLicenses diff (-want +got):\n%s", diff)
+			}
+		})
+	}
+}
+
 func TestDataSource_LegacyGetModuleLicenses(t *testing.T) {
 	ctx, ds, teardown := setup(t)
 	defer teardown()