copy: do not fail if digest mismatches

if the computed digest mismatches the expected one, just log a warning
and use the computed one.

Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>

copy/blob.go

@@ -129,7 +129,9 @@ func (ic *imageCopier) copyBlobFromStream(ctx context.Context, srcReader io.Read
 	}
 
 	if digestingReader.validationFailed { // Coverage: This should never happen.
-		return types.BlobInfo{}, fmt.Errorf("Internal error writing blob %s, digest verification failed but was ignored", srcInfo.Digest)
+		uploadedInfo.Digest = digestingReader.digester.Digest()
+		logrus.Warningf("Digest verification failed for blob %s, using computed %s", srcInfo.Digest, uploadedInfo.Digest)
+		return uploadedInfo, nil
 	}
 	if stream.info.Digest != "" && uploadedInfo.Digest != stream.info.Digest {
 		return types.BlobInfo{}, fmt.Errorf("Internal error writing blob %s, blob with digest %s saved with digest %s", srcInfo.Digest, stream.info.Digest, uploadedInfo.Digest)

copy/digesting_reader.go

@@ -54,9 +54,9 @@ func (d *digestingReader) Read(p []byte) (int, error) {
 		actualDigest := d.digester.Digest()
 		if actualDigest != d.expectedDigest {
 			d.validationFailed = true
-			return 0, fmt.Errorf("Digest did not match, expected %s, got %s", d.expectedDigest, actualDigest)
+		} else {
+			d.validationSucceeded = true
 		}
-		d.validationSucceeded = true
 	}
 	return n, err
 }