Fixes to the list insert functions

[lucasmt]

Fixes two issues in the RepoTokenList.insertSorted and TermAuctionList.insertPending functions:

1. When a node is inserted at the end of the list (including an empty list) the next pointer was not being set to NULL_NODE. This means that if for any reason the storage slot of the next pointer is not initialized to 0, the list would be left in an inconsistent state. It is safer to assign the pointer to NULL_NODE at the time of insertion.
2. When there are two tokens t1 and t2 in the list with the same maturity, with t1 coming first, it was possible to introduce a cycle by inserting t2 again. The insertion function would stop as soon as it found the first token with the same maturity, inserting t2 before t1 without checking to see if it already appeared later on the list. This is fixed by changing the maturity comparison check from <= to <. The same is the case for comparing between auctions in the TermAuctionList.

Summary by CodeRabbit

• New Features

  • Improved logic for inserting tokens and auctions based on maturity, enhancing the order of items in lists.
  • Enhanced linked list integrity through explicit management of node pointers.

• Bug Fixes

  • Resolved issues with node insertion conditions to ensure proper ordering and structure.

[coderabbitai]

Walkthrough

The changes introduce modifications to the RepoTokenList and TermAuctionList libraries, focusing on the insertion logic of linked list nodes. The comparison operators for insertion conditions are updated, ensuring that tokens or auctions with equal maturity are not incorrectly ordered. Additionally, explicit assignments for the next pointers of newly created nodes are added to maintain the integrity of the linked list structure.

Changes

File	Change Summary
src/RepoTokenList.sol	- Updated insertion logic by changing comparison operator from <= to < for repoToken maturity. - Added explicit assignments to next property for head and end nodes.
src/TermAuctionList.sol	- Modified insertion logic by changing comparison operator from <= to < for auctions. - Added explicit assignment to next pointer for new nodes in an empty list.

Possibly related PRs

• miscellaneous audit fixes #22: The changes in the RepoTokenList library involve modifications to the validation logic, specifically altering the comparison logic, which is related to the insertion logic changes in the main PR that also modifies comparison operators in the RepoTokenList.

🐇 In the code, we hop and play,
With tokens and auctions, we find our way.
A tweak here, a change there,
Our lists now dance with utmost care.
Maturity matters, we’ve made it clear,
Hooray for the updates, let’s give a cheer! 🎉

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📜 Recent review details

Configuration used: CodeRabbit UI
Review profile: CHILL

📥 Commits

Files that changed from the base of the PR and between f67a4d5 and 7935718.

📒 Files selected for processing (2)

• src/RepoTokenList.sol (3 hunks)
• src/TermAuctionList.sol (4 hunks)

🔇 Additional comments not posted (8)

src/TermAuctionList.sol (4)

106-106: Approved: Proper initialization of the next pointer

This change correctly initializes the next pointer of the newly inserted node to NULL_NODE when inserting into an empty list. This is a crucial fix that ensures the list is properly terminated, preventing potential issues with uninitialized storage slots and maintaining the integrity of the linked list structure.

---

123-123: Approved: Preventing cycles in auction insertion

The change from <= to < in the comparison is a critical fix. It prevents the creation of cycles in the list when inserting auctions with the same address, which could occur with the previous <= comparison. This ensures that the list maintains a strict ordering based on auction addresses, improving the overall integrity and reliability of the insertPending function.

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139-139: Approved: Proper termination when inserting at the end of the list

This change correctly sets the next pointer of the newly inserted node to NULL_NODE when inserting at the end of the list. This is an important fix that ensures the list is always properly terminated, regardless of where the new node is inserted. It prevents potential issues with uninitialized storage slots and maintains the integrity of the linked list structure.

---

Line range hint 1-380: Summary: Improved safety and correctness of TermAuctionList operations

The changes made to the TermAuctionList library effectively address the issues mentioned in the PR objectives:

1. Proper initialization of next pointers when inserting nodes, both in empty lists and at the end of existing lists.
2. Prevention of potential cycles when inserting auctions with the same address.

These modifications enhance the safety and correctness of the linked list operations without altering the overall structure and logic of the library. The changes are localized to the insertPending function and do not introduce any apparent side effects or inconsistencies with the rest of the codebase.

The improvements contribute to a more robust and reliable implementation of the TermAuctionList, reducing the risk of bugs related to list management and ensuring proper termination of the linked list structure.

src/RepoTokenList.sol (4)

387-387: Explicit initialization of next pointer for new head

This change ensures that when a new repo token is inserted as the head of the list, its next pointer is explicitly set to NULL_NODE. This is a good practice as it prevents potential issues if the storage slot for next is not initialized to zero.

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403-403: Fixed potential cycle creation in insertSorted function

Changing the comparison operator from <= to < addresses the issue of potential cycle creation when inserting tokens with the same maturity. This ensures that tokens with equal maturity are inserted after the current token, maintaining the correct order and preventing cycles in the list.

---

419-419: Explicit initialization of next pointer for end-of-list insertion

This change ensures that when a new repo token is inserted at the end of the list, its next pointer is explicitly set to NULL_NODE. This is consistent with the change on line 387 and maintains the integrity of the list structure.

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Line range hint 1-428: Summary: Improved safety and correctness of repo token list insertion

The changes in this file successfully address the two issues mentioned in the PR objectives:

1. The next pointer is now explicitly set to NULL_NODE when inserting a node at the head or end of the list, preventing potential issues with uninitialized storage slots.
2. The insertion logic for tokens with the same maturity has been fixed by changing the comparison operator from <= to <, preventing the creation of cycles in the list.

These modifications improve the overall safety and correctness of the RepoTokenList library without introducing significant changes to the existing structure. The focused nature of these changes reduces the risk of introducing new bugs while effectively solving the reported issues.

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