Initial push

test/tar_test.go

@@ -0,0 +1,33 @@
+//go:build e2e
+
+package e2e
+
+import (
+	"archive/tar"
+	"errors"
+	"io"
+	"strings"
+)
+
+// firstFileInTar returns the contents of the first regular file in an archive
+// produced by the Docker archive API.
+func firstFileInTar(r io.Reader) (string, error) {
+	tr := tar.NewReader(r)
+	for {
+		hdr, err := tr.Next()
+		if errors.Is(err, io.EOF) {
+			return "", errors.New("archive contains no regular file")
+		}
+		if err != nil {
+			return "", err
+		}
+		if hdr.Typeflag != tar.TypeReg {
+			continue
+		}
+		var b strings.Builder
+		if _, err := io.Copy(&b, tr); err != nil {
+			return "", err
+		}
+		return b.String(), nil
+	}
+}