Properly close files after read/write (#2176)

Author: linzhp

container/go/cmd/zipper/zipper.go

@@ -49,10 +49,21 @@ func main() {
 	if err != nil {
 		log.Fatalf("Unable to read input file: %v", err)
 	}
+	defer func() {
+		if err := f.Close(); err != nil {
+			log.Fatalf("Unable to close %q: %v", *src, err)
+		}
+	}()
+
 	t, err := os.Create(*dst)
 	if err != nil {
 		log.Fatalf("Unable to create output file: %v", err)
 	}
+	defer func() {
+		if err := t.Close(); err != nil {
+			log.Fatalf("Unable to close %q: %v", *dst, err)
+		}
+	}()
 
 	if *decompress {
 		zr, err := gzip.NewReader(f)

container/go/pkg/compat/write.go

@@ -102,6 +102,7 @@ func writeImageLayer(l v1.Layer, idx int, outDir string) error {
 	if err != nil {
 		return errors.Wrapf(err, "unable to create %s to write layer %d", outLayerFile, idx)
 	}
+	defer o.Close()
 	if _, err := io.Copy(o, contents); err != nil {
 		return errors.Wrapf(err, "unable to write the contents of layer %d to %s", idx, outLayerFile)
 	}