Add --ignore option

Packages beginning with the specified path will be ignored.
Imported packages by ignored packages are still checked.

check.go

@@ -42,7 +42,7 @@ func checkMain(_ *cobra.Command, args []string) error {
 		return err
 	}
 
-	libs, err := licenses.Libraries(context.Background(), classifier, args...)
+	libs, err := licenses.Libraries(context.Background(), classifier, ignore, args...)
 	if err != nil {
 		return err
 	}

csv.go

@@ -50,7 +50,7 @@ func csvMain(_ *cobra.Command, args []string) error {
 		return err
 	}
 
-	libs, err := licenses.Libraries(context.Background(), classifier, args...)
+	libs, err := licenses.Libraries(context.Background(), classifier, ignore, args...)
 	if err != nil {
 		return err
 	}

licenses/library.go

@@ -65,7 +65,7 @@ func (e PackagesError) Error() string {
 // A library is a collection of one or more packages covered by the same license file.
 // Packages not covered by a license will be returned as individual libraries.
 // Standard library packages will be ignored.
-func Libraries(ctx context.Context, classifier Classifier, importPaths ...string) ([]*Library, error) {
+func Libraries(ctx context.Context, classifier Classifier, ignoredPaths []string, importPaths ...string) ([]*Library, error) {
 	cfg := &packages.Config{
 		Context: ctx,
 		Mode:    packages.NeedImports | packages.NeedDeps | packages.NeedFiles | packages.NeedName,
@@ -88,6 +88,13 @@ func Libraries(ctx context.Context, classifier Classifier, importPaths ...string
 			// No license requirements for the Go standard library.
 			return false
 		}
+		for _, i := range ignoredPaths {
+			if strings.HasPrefix(p.PkgPath, i) {
+				// Marked to be ignored.
+				return true
+			}
+		}
+
 		if len(p.OtherFiles) > 0 {
 			glog.Warningf("%q contains non-Go code that can't be inspected for further dependencies:\n%s", p.PkgPath, strings.Join(p.OtherFiles, "\n"))
 		}

licenses/library_test.go

@@ -41,6 +41,7 @@ func TestLibraries(t *testing.T) {
 		desc       string
 		importPath string
 		goflags    string
+		ignore     []string
 		wantLibs   []string
 	}{
 		{
@@ -60,6 +61,17 @@ func TestLibraries(t *testing.T) {
 				"github.com/google/go-licenses/licenses/testdata/indirect",
 			},
 		},
+		{
+			desc:       "Ignores a package path",
+			importPath: "github.com/google/go-licenses/licenses/testdata",
+			ignore: []string{
+				"github.com/google/go-licenses/licenses/testdata/direct",
+			},
+			wantLibs: []string{
+				"github.com/google/go-licenses/licenses/testdata",
+				"github.com/google/go-licenses/licenses/testdata/indirect",
+			},
+		},
 		{
 			desc:       "Build tagged package",
 			importPath: "github.com/google/go-licenses/licenses/testdata/tags",
@@ -75,7 +87,7 @@ func TestLibraries(t *testing.T) {
 				os.Setenv("GOFLAGS", test.goflags)
 				defer os.Unsetenv("GOFLAGS")
 			}
-			gotLibs, err := Libraries(context.Background(), classifier, test.importPath)
+			gotLibs, err := Libraries(context.Background(), classifier, test.ignore, test.importPath)
 			if err != nil {
 				t.Fatalf("Libraries(_, %q) = (_, %q), want (_, nil)", test.importPath, err)
 			}

main.go

@@ -29,10 +29,12 @@ var (
 
 	// Flags shared between subcommands
 	confidenceThreshold float64
+	ignore              pathList
 )
 
 func init() {
 	rootCmd.PersistentFlags().Float64Var(&confidenceThreshold, "confidence_threshold", 0.9, "Minimum confidence required in order to positively identify a license.")
+	rootCmd.PersistentFlags().Var(&ignore, "ignore", "Module path prefixes to be ignored. Can be specified multiple times.")
 }
 
 func main() {

pathlist.go

@@ -0,0 +1,37 @@
+// Copyright 2019 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 main
+
+import (
+	"fmt"
+)
+
+type pathList []string
+
+func (l *pathList) String() string {
+	if len(*l) == 0 {
+		return ""
+	}
+	return fmt.Sprintf("%v", *l)
+}
+
+func (l *pathList) Set(v string) error {
+	*l = append(*l, v)
+	return nil
+}
+
+func (l *pathList) Type() string {
+	return "string"
+}

save.go

@@ -81,7 +81,7 @@ func saveMain(_ *cobra.Command, args []string) error {
 		return err
 	}
 
-	libs, err := licenses.Libraries(context.Background(), classifier, args...)
+	libs, err := licenses.Libraries(context.Background(), classifier, ignore, args...)
 	if err != nil {
 		return err
 	}