add test for empty bucket handling

2 files changed, 36 insertions, 8 deletions

diff --git a/c/cursor.go b/c/cursor.go
index 21f1576..4c00767 100644
--- a/c/cursor.go
+++ b/c/cursor.go
@@ -196,8 +196,8 @@ leaf_element *page_leaf_element(page *p, uint16_t index) {
 void cursor_key_value(bolt_cursor *c, bolt_val *key, bolt_val *value, uint32_t *flags) {
 	elem_ref *ref = cursor_current(c);
 
-	// If stack is empty return null.
-	if (ref == NULL) {
+	// If stack or current page is empty return null.
+	if (ref == NULL || ref->page->count == 0) {
 		key->size = value->size = 0;
 		key->data = value->data = NULL;
 		*flags = 0;
@@ -337,7 +337,9 @@ func (c *Cursor) First() (key, value []byte) {
 	var k, v C.bolt_val
 	var flags C.uint32_t
 	C.bolt_cursor_first(c.C, &k, &v, &flags)
-	if k.data == nil {
+	fmt.Printf("key: %#v, value: %#v\n", k, v)
+	fmt.Printf("k.data: %#v, k.size: %#v\n", uintptr(k.data), int(k.size))
+	if uintptr(k.data) == uintptr(0) {
 		return nil, nil
 	}
 	return C.GoBytes(k.data, C.int(k.size)), C.GoBytes(v.data, C.int(v.size))
@@ -349,7 +351,8 @@ func (c *Cursor) Next() (key, value []byte) {
 	var k, v C.bolt_val
 	var flags C.uint32_t
 	C.bolt_cursor_next(c.C, &k, &v, &flags)
-	if k.data == nil {
+	fmt.Printf("key: %#v, value: %#v\n", k, v)
+	if k.size == 0 {
 		return nil, nil
 	}
 	return C.GoBytes(k.data, C.int(k.size)), C.GoBytes(v.data, C.int(v.size))
@@ -366,9 +369,10 @@ func (c *Cursor) Seek(seek []byte) (key, value []byte, flags int) {
 		_seek.data = unsafe.Pointer(&seek[0])
 	}
 	C.bolt_cursor_seek(c.C, _seek, &k, &v, &_flags)
-	//fmt.Printf("Key %v [%v]\n", k.data, k.size)
-	//fmt.Printf("Value %v [%v]\n", k.data, k.size)
-	if k.data == nil {
+	fmt.Printf("Key %#v [%#v]\n", k.data, k.size)
+	fmt.Printf("Value %#v [%#v]\n", k.data, k.size)
+	fmt.Printf("key: %#v, value: %#v\n", k, v)
+	if k.size == 0 {
 		return nil, nil, 0
 	}
 
diff --git a/c/cursor_test.go b/c/cursor_test.go
index fa1e6bb..5a8f3e0 100644
--- a/c/cursor_test.go
+++ b/c/cursor_test.go
@@ -11,7 +11,7 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
-// Ensure that the C cursor can
+// Ensure that the C cursor can seek to first element.
 func TestCursor_First(t *testing.T) {
 	withDB(func(db *bolt.DB) {
 		db.Update(func(tx *bolt.Tx) error {
@@ -28,6 +28,30 @@ func TestCursor_First(t *testing.T) {
 	})
 }
 
+// Ensure that a C cursor handles empty bucket properly
+func TestCursor_Empty(t *testing.T) {
+	withDB(func(db *bolt.DB) {
+		db.Update(func(tx *bolt.Tx) error {
+			tx.CreateBucket([]byte("widgets"))
+			return nil
+		})
+		db.View(func(tx *bolt.Tx) error {
+			c := NewCursor(tx.Bucket([]byte("widgets")))
+			key, value := c.First()
+			assert.Equal(t, nil, key)
+			assert.Equal(t, nil, value)
+			key, value = c.Next()
+			assert.Equal(t, nil, key)
+			assert.Equal(t, nil, value)
+			key, value, flags := c.Seek([]byte("bar"))
+			assert.Equal(t, nil, key)
+			assert.Equal(t, nil, value)
+			assert.Equal(t, 0, flags)
+			return nil
+		})
+	})
+}
+
 // Ensure that a C cursor can seek to the appropriate keys.
 func TestCursor_Seek(t *testing.T) {
 	withDB(func(db *bolt.DB) {