validate.Layer: handle validation for layer content that is not compr…

…essed

Fixes #1826

pkg/v1/validate/layer.go

@@ -21,6 +21,8 @@ import (
 	"encoding/hex"
 	"errors"
 	"fmt"
+	"github.com/google/go-containerregistry/internal/compression"
+	comp "github.com/google/go-containerregistry/pkg/compression"
 	"io"
 	"strings"
 
@@ -128,21 +130,32 @@ func computeLayer(layer v1.Layer) (*computedLayer, error) {
 	}()
 
 	// Read the bytes through gzip.Reader to compute the DiffID.
-	uncompressed, err := gzip.NewReader(pr)
-	if err != nil {
-		return nil, err
+	var uncompressed io.ReadCloser
+	// if layer content is known to be not compressed, don't wrap in gzip reader
+	if cp, pr, err := compression.PeekCompression(pr); err == nil && cp == comp.None {
+		uncompressed = io.NopCloser(pr)
+	} else {
+		uncompressed, err = gzip.NewReader(pr)
+		if err != nil {
+			return nil, err
+		}
 	}
 	diffider := crypto.SHA256.New()
 	hashUncompressed := io.TeeReader(uncompressed, diffider)
 
-	// Ensure there aren't duplicate file paths.
+	// Ensure there aren't duplicate file paths if content is tar.
+	firstTarEntry := true
 	tarReader := tar.NewReader(hashUncompressed)
 	files := make(map[string]struct{})
 	for {
 		hdr, err := tarReader.Next()
 		if errors.Is(err, io.EOF) {
 			break
+		} else if firstTarEntry && (errors.Is(err, io.ErrUnexpectedEOF) || errors.Is(err, tar.ErrHeader)) {
+			// if the first entry cannot be read, content is not a valid tar
+			break
 		}
+		firstTarEntry = false
 		if err != nil {
 			return nil, err
 		}

pkg/v1/validate/layer_test.go

@@ -0,0 +1,95 @@
+// Copyright 2019 Google LLC 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 validate
+
+import (
+	"bytes"
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/google/go-containerregistry/pkg/v1/partial"
+	"github.com/google/go-containerregistry/pkg/v1/random"
+	"github.com/google/go-containerregistry/pkg/v1/types"
+	"io"
+	"testing"
+)
+
+// Tests that validation succeeds for valid layer that contains GZ-compressed tar content.
+func TestValidateCompressedLayer(t *testing.T) {
+	layer, err := random.Layer(100, types.OCILayer)
+	if err != nil {
+		t.Error("could not create layer:", err)
+	}
+	if err := Layer(layer); err != nil {
+		t.Error("compressed layer failed validation:", err)
+	}
+}
+
+// Tests that validation succeeds for valid layer that contains uncompressed tar content.
+func TestValidateLayerWithTarContentNotCompressed(t *testing.T) {
+	layer, err := random.Layer(100, types.DockerUncompressedLayer)
+	if err != nil {
+		t.Error("could not create layer:", err)
+	}
+	tarReadCloser, err := layer.Uncompressed()
+	if err != nil {
+		t.Error("could not get tar content:", err)
+	}
+	tarBytes, err := io.ReadAll(tarReadCloser)
+	if err != nil {
+		t.Error("could not read tar content:", err)
+	}
+	layer, err = partial.CompressedToLayer(&compressedBytesLayer{
+		content: tarBytes,
+	})
+	if err != nil {
+		t.Error("could not create layer:", err)
+	}
+	if err := Layer(layer); err != nil {
+		t.Error("compressed layer failed validation:", err)
+	}
+}
+
+// Tests that validation succeeds for valid layer that contains uncompressed arbitrary content.
+func TestValidateLayerWithContentNotCompressed(t *testing.T) {
+	layer, err := partial.CompressedToLayer(&compressedBytesLayer{
+		content: []byte("test-content"),
+	})
+	if err != nil {
+		t.Error("could not create layer:", err)
+	}
+	if err := Layer(layer); err != nil {
+		t.Error("compressed layer failed validation:", err)
+	}
+}
+
+type compressedBytesLayer struct {
+	content []byte
+}
+
+func (cl *compressedBytesLayer) Digest() (v1.Hash, error) {
+	hash, _, err := v1.SHA256(bytes.NewReader(cl.content))
+	return hash, err
+}
+
+func (cl *compressedBytesLayer) Compressed() (io.ReadCloser, error) {
+	return io.NopCloser(bytes.NewReader(cl.content)), nil
+}
+
+func (cl *compressedBytesLayer) Size() (int64, error) {
+	return int64(len(cl.content)), nil
+}
+
+func (cl *compressedBytesLayer) MediaType() (types.MediaType, error) {
+	return types.OCIContentDescriptor, nil
+}