fix the code scanning alert - Multiplication resul…

[enigma-hh]

…t converted to larger type #{564}

What problem were solved in this pull request?

In bplus_tree.cpp, there was a risk of integer overflow in the multiplication operation this->size() * _item_size(). The multiplication was initially performed using the int type . Before being converted to a larger type ( size_type), an overflow might occur. This could lead to incorrect parameters being passed to subsequent operations like node_remove_items, potentially causing issues such as memory over - boundaries and logical errors.
Issue Number: close #564

Problem:

What is changed and how it works?

Changed Code: In the LeafIndexNodeHandler::move_to method and LeafIndexNodeHandler::append method the parameters of the multiplication operation are converted for type safety.
1.LeafIndexNodeHandler::move_to method：
From:

RC rc = mtr_.logger().node_remove_items(*this, 0, span<const char>(__item_at(0), this->size() * item_size()), this->size());

To:

RC rc = mtr_.logger().node_remove_items(*this, 0, span<const char>(__item_at(0), static_cast<size_t>(this->size()) * static_cast<size_t>(item_size())), this->size());

2.LeafIndexNodeHandler::append method：
From:

RC rc = mtr_.logger().node_insert_items(*this, size(), span<const char>(items, num * item_size()), num);

To:

RC rc = mtr_.logger().node_insert_items(*this, size(), span<const char>(items, static_cast<size_t>(num) * static_cast<size_t>(item_size())), num);

Other information

[CLAassistant]

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[nautaa]

directly use static_cast is better?

[nautaa]

LGTM

[nautaa]

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