Add xattr stream package test

Ensure that the selinux header has the right format.  The included
minimal tar test data contains a file with a selinux header captured via
`tar` as a reference.

Signed-off-by: Roman Mohr <[email protected]>

Author: rmohr

pkg/xattr/BUILD.bazel

@@ -1,8 +1,16 @@
-load("@io_bazel_rules_go//go:def.bzl", "go_library")
+load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
 
 go_library(
     name = "xattr",
     srcs = ["xattr.go"],
     importpath = "github.com/rmohr/bazeldnf/pkg/xattr",
     visibility = ["//visibility:public"],
 )
+
+go_test(
+    name = "xattr_test",
+    srcs = ["xattr_test.go"],
+    data = glob(["testdata/**"]),
+    embed = [":xattr"],
+    deps = ["@com_github_onsi_gomega//:go_default_library"],
+)

pkg/xattr/testdata/xattr.tar

@@ -37,7 +37,7 @@ func SetSELinuxLabel(pax map[string]string, label string) error {
 	if label == "" {
 		return fmt.Errorf("label must not be empty, but got '%s'", label)
 	}
-	pax[selinux_header] = fmt.Sprintf("%s\x00", label)
+	pax[selinux_header] = fmt.Sprintf("%s\x00",label)
 	return nil
 }
 
@@ -50,15 +50,8 @@ func Apply(reader *tar.Reader, writer *tar.Writer, capabilties map[string][]stri
 			return err
 		}
 
-		if caps, exists := capabilties[entry.Name]; exists {
-			if err := AddCapabilities(entry.PAXRecords, caps); err != nil {
-				return err
-			}
-		}
-		if l, exists := labels[entry.Name]; exists {
-			if err := SetSELinuxLabel(entry.PAXRecords, l); err != nil {
-				return err
-			}
+		if err := enrichEntry(entry, capabilties, labels); err != nil {
+			return err
 		}
 
 		entry.Format = tar.FormatPAX
@@ -71,3 +64,21 @@ func Apply(reader *tar.Reader, writer *tar.Writer, capabilties map[string][]stri
 	}
 	return nil
 }
+
+func enrichEntry(entry *tar.Header, capabilties map[string][]string, labels map[string]string) error {
+	if entry.PAXRecords == nil {
+		entry.PAXRecords = map[string]string{}
+	}
+
+	if caps, exists := capabilties[entry.Name]; exists {
+		if err := AddCapabilities(entry.PAXRecords, caps); err != nil {
+			return err
+		}
+	}
+	if l, exists := labels[entry.Name]; exists {
+		if err := SetSELinuxLabel(entry.PAXRecords, l); err != nil {
+			return err
+		}
+	}
+	return nil
+}

pkg/xattr/xattr.go

@@ -0,0 +1,45 @@
+package xattr
+
+import (
+	"archive/tar"
+	"fmt"
+	"io"
+	"os"
+	"testing"
+
+	. "github.com/onsi/gomega"
+)
+
+var g *GomegaWithT
+
+func TestSettingSELinuxLabel(t *testing.T) {
+	g = NewGomegaWithT(t)
+	referenceEntry, err := getHeader("blub")
+	g.Expect(err).ToNot(HaveOccurred())
+
+	generatedEntry := &tar.Header{Name: "blub"}
+	labels := map[string]string{"blub": "unconfined_u:object_r:user_home_t:s0", "somethingelse": "something"}
+
+	g.Expect(enrichEntry(generatedEntry, nil, labels)).To(Succeed())
+
+	g.Expect(generatedEntry.PAXRecords[selinux_header]).To(Equal(referenceEntry.PAXRecords[selinux_header]))
+}
+
+func getHeader(name string) (*tar.Header, error) {
+	f, err := os.Open("testdata/xattr.tar")
+	g.Expect(err).ToNot(HaveOccurred())
+	defer f.Close()
+	r := tar.NewReader(f)
+	for {
+		entry, err := r.Next()
+		if err == io.EOF {
+			break
+		} else if err != nil {
+			g.Expect(err).ToNot(HaveOccurred())
+		}
+		if entry.Name == name {
+			return entry, nil
+		}
+	}
+	return nil, fmt.Errorf("entry %v does not exist", name)
+}