tests/reverse: implement (skipped) xattr test

v1api reverse mode did not have xattr support,
the v2api version may have at some point. Prep the
test already.

tests/reverse/xattr_test.go

@@ -0,0 +1,66 @@
+package reverse_test
+
+import (
+	"fmt"
+	"io/ioutil"
+	"path/filepath"
+	"syscall"
+	"testing"
+
+	"github.com/pkg/xattr"
+)
+
+func xattrSupported(path string) bool {
+	_, err := xattr.LGet(path, "user.xattrSupported-dummy-value")
+	if err == nil {
+		return true
+	}
+	err2 := err.(*xattr.Error)
+	if err2.Err == syscall.EOPNOTSUPP {
+		return false
+	}
+	return true
+}
+
+func TestXattrList(t *testing.T) {
+	t.Skip("TODO: not implemented yet in reverse mode")
+
+	if !xattrSupported(dirA) {
+		t.Skip()
+	}
+	fnA := filepath.Join(dirA, t.Name())
+	err := ioutil.WriteFile(fnA, nil, 0700)
+	if err != nil {
+		t.Fatalf("creating empty file failed: %v", err)
+	}
+	val := []byte("xxxxxxxxyyyyyyyyyyyyyyyzzzzzzzzzzzzz")
+	num := 20
+	var namesA map[string]string
+	for i := 1; i <= num; i++ {
+		attr := fmt.Sprintf("user.TestXattrList.%02d", i)
+		err = xattr.LSet(fnA, attr, val)
+		if err != nil {
+			t.Fatal(err)
+		}
+		namesA[attr] = string(val)
+	}
+	fnC := filepath.Join(dirC, t.Name())
+	tmp, err := xattr.LList(fnC)
+	if err != nil {
+		t.Fatal(err)
+	}
+	var namesC map[string]string
+	for _, n := range tmp {
+		namesC[n] = string(val)
+	}
+	if len(namesA) != len(namesC) {
+		t.Errorf("wrong number of names, want=%d have=%d", len(namesA), len(namesC))
+	}
+	for i := range namesC {
+		valA := namesA[i]
+		valC := namesC[i]
+		if valC != valA {
+			t.Errorf("mismatch on attr %q: valA = %q, valC = %q", i, valA, valC)
+		}
+	}
+}