copy: provide compression info about copied blobs

When copying a compressed blob without making any modifications to it, set the CompressionFormat in the returned BlobInfo to reflect the compression algorithm that was used to compress the blob. Signed-off-by: Nalin Dahyabhai <[email protected]>
containers · Feb 25, 2021 · e5f19ba · e5f19ba
1 parent 86298a3
commit e5f19ba
Showing 1 changed file with 9 additions and 1 deletion.
diff --git a/copy/copy.go b/copy/copy.go
@@ -1349,7 +1349,15 @@ func (c *copier) copyBlobFromStream(ctx context.Context, srcStream io.Reader, sr
 		compressionOperation = types.PreserveOriginal
 		inputInfo = srcInfo
 		uploadCompressorName = srcCompressorName
-		uploadCompressionFormat = nil
+		// Remember if the original blob was compressed, and if so how, so that if
+		// LayerInfosForCopy() returned something that differs from what was in the
+		// source's manifest, and UpdatedImage() needs to call UpdateLayerInfos(),
+		// it will be able to correctly derive the MediaType for the copied blob.
+		if isCompressed {
+			uploadCompressionFormat = &compressionFormat
+		} else {
+			uploadCompressionFormat = nil
+		}
 	}
 
 	// Perform image encryption for valid mediatypes if ociEncryptConfig provided