LibSQL: Fix BTree corruption in TreeNode::split

After splitting a node, the new node was written to the same pointer as
the current node - probably a copy / paste error. This new code requires
a `.pointer() -> u32` to exist on the object to be serialized,
preventing this issue from happening again.

Fixes #15844.

Tests/LibSQL/TestSqlStatementExecution.cpp

@@ -754,4 +754,23 @@ TEST_CASE(binary_operator_failure)
     expect_failure(move(result), '&');
 }
 
+TEST_CASE(describe_large_table_after_persist)
+{
+    ScopeGuard guard([]() { unlink(db_name); });
+    {
+        auto database = SQL::Database::construct(db_name);
+        EXPECT(!database->open().is_error());
+
+        auto result = execute(database, "CREATE TABLE Cookies ( name TEXT, value TEXT, same_site INTEGER, creation_time INTEGER, last_access_time INTEGER, expiry_time INTEGER, domain TEXT, path TEXT, secure INTEGER, http_only INTEGER, host_only INTEGER, persistent INTEGER );");
+        EXPECT_EQ(result.command(), SQL::SQLCommand::Create);
+    }
+    {
+        auto database = SQL::Database::construct(db_name);
+        EXPECT(!database->open().is_error());
+
+        auto result = execute(database, "DESCRIBE TABLE Cookies;");
+        EXPECT_EQ(result.size(), 12u);
+    }
+}
+
 }

Userland/Libraries/LibSQL/BTree.cpp

@@ -56,7 +56,7 @@ TreeNode* BTree::new_root()
 {
     set_pointer(new_record_pointer());
     m_root = make<TreeNode>(*this, nullptr, m_root.leak_ptr(), pointer());
-    serializer().serialize_and_write(*m_root.ptr(), m_root->pointer());
+    serializer().serialize_and_write(*m_root.ptr());
     if (on_new_root)
         on_new_root();
     return m_root;

Userland/Libraries/LibSQL/BTreeIterator.cpp

@@ -232,7 +232,7 @@ bool BTreeIterator::update(Key const& new_value)
 
     // We are friend of BTree and TreeNode. Don't know how I feel about that.
     m_current->m_entries[m_index] = new_value;
-    m_current->tree().serializer().serialize_and_write(*m_current, m_current->pointer());
+    m_current->tree().serializer().serialize_and_write(*m_current);
     return true;
 }
 

Userland/Libraries/LibSQL/Database.cpp

@@ -223,7 +223,7 @@ ErrorOr<void> Database::update(Row& tuple)
     VERIFY(m_table_cache.get(tuple.table()->key().hash()).has_value());
     // TODO Check constraints
     m_serializer.reset();
-    m_serializer.serialize_and_write<Tuple>(tuple, tuple.pointer());
+    m_serializer.serialize_and_write<Tuple>(tuple);
 
     // TODO update indexes defined on table.
     return {};

Userland/Libraries/LibSQL/HashIndex.cpp

@@ -140,7 +140,7 @@ bool HashBucket::insert(Key const& key)
         return false;
     }
     m_entries.append(key);
-    m_hash_index.serializer().serialize_and_write(*this, pointer());
+    m_hash_index.serializer().serialize_and_write(*this);
     return true;
 }
 
@@ -226,10 +226,10 @@ HashIndex::HashIndex(Serializer& serializer, NonnullRefPtr<TupleDescriptor> cons
     } else {
         auto bucket = append_bucket(0u, 1u, new_record_pointer());
         bucket->m_inflated = true;
-        serializer.serialize_and_write(*bucket, bucket->pointer());
+        serializer.serialize_and_write(*bucket);
         bucket = append_bucket(1u, 1u, new_record_pointer());
         bucket->m_inflated = true;
-        serializer.serialize_and_write(*bucket, bucket->pointer());
+        serializer.serialize_and_write(*bucket);
         m_nodes.append(first_node);
         write_directory_to_write_ahead_log();
     }
@@ -283,7 +283,7 @@ HashBucket* HashIndex::get_bucket_for_insert(Key const& key)
                 }
                 if (moved > 0) {
                     dbgln_if(SQL_DEBUG, "Moved {} entries from bucket #{} to #{}", moved, base_index, ix);
-                    serializer().serialize_and_write(*sub_bucket, sub_bucket->pointer());
+                    serializer().serialize_and_write(*sub_bucket);
                 }
                 total_moved += moved;
             }
@@ -292,7 +292,7 @@ HashBucket* HashIndex::get_bucket_for_insert(Key const& key)
             else
                 dbgln_if(SQL_DEBUG, "Nothing redistributed from bucket #{}", base_index);
             bucket->set_local_depth(bucket->local_depth() + 1);
-            serializer().serialize_and_write(*bucket, bucket->pointer());
+            serializer().serialize_and_write(*bucket);
             write_directory_to_write_ahead_log();
 
             auto bucket_after_redistribution = get_bucket(key_hash % size());
@@ -327,7 +327,7 @@ void HashIndex::write_directory_to_write_ahead_log()
     size_t num_node = 0u;
     while (offset < size()) {
         HashDirectoryNode node(*this, num_node, offset);
-        serializer().serialize_and_write(node, node.pointer());
+        serializer().serialize_and_write(node);
         offset += node.number_of_pointers();
     }
 }

Userland/Libraries/LibSQL/Serializer.h

@@ -108,12 +108,12 @@ public:
     void serialize(String const&);
 
     template<typename T>
-    bool serialize_and_write(T const& t, u32 pointer)
+    bool serialize_and_write(T const& t)
     {
         VERIFY(m_heap.ptr() != nullptr);
         reset();
         serialize<T>(t);
-        m_heap->add_to_wal(pointer, m_buffer);
+        m_heap->add_to_wal(t.pointer(), m_buffer);
         return true;
     }
 

Userland/Libraries/LibSQL/TreeNode.cpp

@@ -172,7 +172,7 @@ bool TreeNode::update_key_pointer(Key const& key)
             if (m_entries[ix].pointer() != key.pointer()) {
                 m_entries[ix].set_pointer(key.pointer());
                 dump_if(SQL_DEBUG, "To WAL");
-                tree().serializer().serialize_and_write<TreeNode>(*this, pointer());
+                tree().serializer().serialize_and_write<TreeNode>(*this);
             }
             return true;
         }
@@ -277,7 +277,7 @@ void TreeNode::just_insert(Key const& key, TreeNode* right)
                 split();
             } else {
                 dump_if(SQL_DEBUG, "To WAL");
-                tree().serializer().serialize_and_write(*this, pointer());
+                tree().serializer().serialize_and_write(*this);
             }
             return;
         }
@@ -289,7 +289,7 @@ void TreeNode::just_insert(Key const& key, TreeNode* right)
         split();
     } else {
         dump_if(SQL_DEBUG, "To WAL");
-        tree().serializer().serialize_and_write(*this, pointer());
+        tree().serializer().serialize_and_write(*this);
     }
 }
 
@@ -327,9 +327,9 @@ void TreeNode::split()
     auto median = m_entries.take_last();
 
     dump_if(SQL_DEBUG, "Split Left To WAL");
-    tree().serializer().serialize_and_write(*this, pointer());
+    tree().serializer().serialize_and_write(*this);
     new_node->dump_if(SQL_DEBUG, "Split Right to WAL");
-    tree().serializer().serialize_and_write(*new_node, pointer());
+    tree().serializer().serialize_and_write(*new_node);
 
     m_up->just_insert(median, new_node);
 }