ioctx: added ListXattrs()

Added a function to List Xattrs, which returns a map of all xattrs set
on an object, errors out otherwise

Signed-off-by: Abhishek Lekshmanan <abhishek.lekshmanan@gmail.com>

rados/ioctx.go

@@ -234,3 +234,39 @@ func (ioctx *IOContext) SetXattr(object string, name string, data []byte) error
 		return RadosError(int(ret))
 	}
 }
+
+// function that lists all the xattrs for an object, since xattrs are
+// a k-v pair, this function returns a map of k-v pairs on
+// success, error code on failure
+func (ioctx *IOContext) ListXattrs(oid string) (map[string]string, error) {
+	c_oid := C.CString(oid)
+	defer C.free(unsafe.Pointer(c_oid))
+
+	var it C.rados_xattrs_iter_t
+
+	ret := C.rados_getxattrs(ioctx.ioctx, c_oid, &it)
+	if ret < 0 {
+		return nil, RadosError(ret)
+	}
+	defer func() { C.rados_getxattrs_end(it) }()
+	m := make(map[string]string)
+	for {
+		var c_name, c_val *C.char
+		var c_len C.size_t
+		defer C.free(unsafe.Pointer(c_name))
+		defer C.free(unsafe.Pointer(c_val))
+
+		ret := C.rados_getxattrs_next(it, &c_name, &c_val, &c_len)
+		if ret < 0 {
+			return nil, RadosError(int(ret))
+		}
+		// rados api returns a null name,val & 0-length upon
+		// end of iteration
+		if c_name == nil {
+			return m, nil // stop iteration
+		}
+		m[C.GoString(c_name)] = C.GoStringN(c_val, (C.int)(c_len))
+	}
+
+	panic("Invalid State")
+}

rados/rados_test.go

@@ -471,3 +471,38 @@ func TestReadWriteXattr(t *testing.T) {
 
 	pool.Destroy()
 }
+
+func TestListXattrs(t *testing.T) {
+	conn, _ := rados.NewConn()
+	conn.ReadDefaultConfigFile()
+	conn.Connect()
+
+	// make pool
+	pool_name := GetUUID()
+	err := conn.MakePool(pool_name)
+	assert.NoError(t, err)
+
+	pool, err := conn.OpenIOContext(pool_name)
+	assert.NoError(t, err)
+
+	bytes_in := []byte("input data")
+	err = pool.Write("obj", bytes_in, 0)
+	assert.NoError(t, err)
+
+	input_xattrs := make(map[string]string)
+	for i := 0; i < 200; i++ {
+		name := fmt.Sprintf("key_%d", i)
+		data := []byte(GetUUID())
+		err = pool.SetXattr("obj", name, data)
+		assert.NoError(t, err)
+		input_xattrs[name] = string(data)
+	}
+
+	output_xattrs := make(map[string]string)
+	output_xattrs, err = pool.ListXattrs("obj")
+	assert.NoError(t, err)
+	assert.Equal(t, len(input_xattrs), len(output_xattrs))
+	assert.Equal(t, input_xattrs, output_xattrs)
+
+	pool.Destroy()
+}