Pluggable blob storage for pkg/registry

internal/verify/verify.go

@@ -38,6 +38,18 @@ type verifyReader struct {
 	gotSize, wantSize int64
 }
 
+// Error provides information about the failed hash verification.
+type Error struct {
+	got     string
+	want    v1.Hash
+	gotSize int64
+}
+
+func (v Error) Error() string {
+	return fmt.Sprintf("error verifying %s checksum after reading %d bytes; got %q, want %q",
+		v.want.Algorithm, v.gotSize, v.got, v.want)
+}
+
 // Read implements io.Reader
 func (vc *verifyReader) Read(b []byte) (int, error) {
 	n, err := vc.inner.Read(b)
@@ -46,10 +58,13 @@ func (vc *verifyReader) Read(b []byte) (int, error) {
 		if vc.wantSize != SizeUnknown && vc.gotSize != vc.wantSize {
 			return n, fmt.Errorf("error verifying size; got %d, want %d", vc.gotSize, vc.wantSize)
 		}
-		got := hex.EncodeToString(vc.hasher.Sum(make([]byte, 0, vc.hasher.Size())))
+		got := hex.EncodeToString(vc.hasher.Sum(nil))
 		if want := vc.expected.Hex; got != want {
-			return n, fmt.Errorf("error verifying %s checksum after reading %d bytes; got %q, want %q",
-				vc.expected.Algorithm, vc.gotSize, got, want)
+			return n, Error{
+				got:     vc.expected.Algorithm + ":" + got,
+				want:    vc.expected,
+				gotSize: vc.gotSize,
+			}
 		}
 	}
 	return n, err
@@ -69,9 +84,9 @@ func ReadCloser(r io.ReadCloser, size int64, h v1.Hash) (io.ReadCloser, error) {
 	if err != nil {
 		return nil, err
 	}
-	var r2 io.Reader = r
+	r2 := io.TeeReader(r, w) // pass all writes to the hasher.
 	if size != SizeUnknown {
-		r2 = io.LimitReader(io.TeeReader(r, w), size)
+		r2 = io.LimitReader(r2, size) // if we know the size, limit to that size.
 	}
 	return &and.ReadCloser{
 		Reader: &verifyReader{

internal/verify/verify_test.go

@@ -30,6 +30,7 @@ func mustHash(s string, t *testing.T) v1.Hash {
 	if err != nil {
 		t.Fatalf("v1.SHA256(%s) = %v", s, err)
 	}
+	t.Logf("Hashed: %q -> %q", s, h)
 	return h
 }
 
@@ -59,6 +60,19 @@ func TestVerification(t *testing.T) {
 	}
 }
 
+func TestVerificationSizeUnknown(t *testing.T) {
+	want := "This is the input string."
+	buf := bytes.NewBufferString(want)
+
+	verified, err := ReadCloser(ioutil.NopCloser(buf), SizeUnknown, mustHash(want, t))
+	if err != nil {
+		t.Fatal("ReadCloser() =", err)
+	}
+	if _, err := ioutil.ReadAll(verified); err != nil {
+		t.Error("ReadAll() =", err)
+	}
+}
+
 func TestBadHash(t *testing.T) {
 	h := v1.Hash{
 		Algorithm: "fake256",