rbd: add GroupList implementing rbd_group_list

Signed-off-by: John Mulligan <jmulligan@redhat.com>

rbd/group.go

@@ -10,6 +10,8 @@ import "C"
 import (
 	"unsafe"
 
+	"github.com/ceph/go-ceph/internal/cutil"
+	"github.com/ceph/go-ceph/internal/retry"
 	"github.com/ceph/go-ceph/rados"
 )
 
@@ -51,3 +53,34 @@ func GroupRename(ioctx *rados.IOContext, src, dest string) error {
 	ret := C.rbd_group_rename(cephIoctx(ioctx), cSrc, cDest)
 	return getError(ret)
 }
+
+// GroupList returns a slice of image group names.
+//
+// Implements:
+//  int rbd_group_list(rados_ioctx_t p, char *names, size_t *size);
+func GroupList(ioctx *rados.IOContext) ([]string, error) {
+	var (
+		buf []byte
+		err error
+		ret C.int
+	)
+	retry.WithSizes(1024, 262144, func(size int) retry.Hint {
+		cSize := C.size_t(size)
+		buf = make([]byte, cSize)
+		ret = C.rbd_group_list(
+			cephIoctx(ioctx),
+			(*C.char)(unsafe.Pointer(&buf[0])),
+			&cSize)
+		err = getErrorIfNegative(ret)
+		return retry.Size(int(cSize)).If(err == errRange)
+	})
+
+	if err != nil {
+		return nil, err
+	}
+
+	// cSize is not set to the expected size when it is sufficiently large
+	// but ret will be set to the size in a non-error condition.
+	groups := cutil.SplitBuffer(buf[:ret])
+	return groups, nil
+}

rbd/group_test.go

@@ -67,3 +67,49 @@ func TestGroupRename(t *testing.T) {
 	err = GroupRename(ioctx, "club1", "nowhere")
 	assert.Error(t, err)
 }
+
+func TestGroupList(t *testing.T) {
+	conn := radosConnect(t)
+	require.NotNil(t, conn)
+	defer conn.Shutdown()
+
+	poolname := GetUUID()
+	err := conn.MakePool(poolname)
+	require.NoError(t, err)
+	defer conn.DeletePool(poolname)
+
+	ioctx, err := conn.OpenIOContext(poolname)
+	require.NoError(t, err)
+	defer ioctx.Destroy()
+
+	err = GroupCreate(ioctx, "uno")
+	assert.NoError(t, err)
+	err = GroupCreate(ioctx, "dos")
+	assert.NoError(t, err)
+	err = GroupCreate(ioctx, "tres")
+	assert.NoError(t, err)
+
+	l, err := GroupList(ioctx)
+	assert.NoError(t, err)
+	if assert.Len(t, l, 3) {
+		assert.Contains(t, l, "uno")
+		assert.Contains(t, l, "dos")
+		assert.Contains(t, l, "tres")
+	}
+
+	err = GroupRemove(ioctx, "uno")
+	assert.NoError(t, err)
+	err = GroupRemove(ioctx, "dos")
+	assert.NoError(t, err)
+	err = GroupRemove(ioctx, "tres")
+	assert.NoError(t, err)
+
+	l, err = GroupList(ioctx)
+	assert.NoError(t, err)
+	assert.Len(t, l, 0)
+
+	// test that GroupList panics if passed a nil ioctx
+	assert.Panics(t, func() {
+		GroupList(nil)
+	})
+}