Owner Two Step Transfer Module

Two-step ERC-173 ownership transfer logic

Key Features

• Two-step handoff: current owner calls transferOwnership; the nominated address calls acceptOwnership to finalize (unlike single-step OwnerTransferMod).
• Uses erc8042:erc173.owner and erc8042:erc173.owner.pending; same layout as Owner Two Step Transfer Facet.
• File-level getOwnerStorage, getPendingOwnerStorage, transferOwnership, and acceptOwnership; emits OwnershipTransferStarted then OwnershipTransferred when acceptance completes.

Module Usage

Import this module into facets or shared setup code. Its helpers are file-level (effectively internal to your compilation unit). Call them from your facet’s external entrypoints.

Storage follows the diamond slot layout in this file; any code using the same OWNER_STORAGE_POSITION or PENDING_OWNER_STORAGE_POSITION shares state.

See Facets & Modules for more information.

Storage

State Variables

Property	Type	Description
OWNER_STORAGE_POSITION	bytes32	Owner storage position within the diamond (Value: keccak256("erc173.owner"))
PENDING_OWNER_STORAGE_POSITION	bytes32	Pending owner storage position within the diamond (Value: keccak256("erc173.owner.pending"))

OwnerStorage

Definition

/** @custom:storage-location erc8042:erc173.owner */
struct OwnerStorage {
  address owner;
}

PendingOwnerStorage

Definition

/** @custom:storage-location erc8042:erc173.owner.pending */
struct PendingOwnerStorage {
  address pendingOwner;
}

Functions

getOwnerStorage

Returns a storage pointer to OwnerStorage at OWNER_STORAGE_POSITION using inline assembly.

function getOwnerStorage() pure returns (OwnerStorage storage s);

Returns:

Property	Type	Description
s	OwnerStorage storage	The owner struct in diamond storage.

---

getPendingOwnerStorage

Returns a storage pointer to PendingOwnerStorage at PENDING_OWNER_STORAGE_POSITION using inline assembly.

function getPendingOwnerStorage() pure returns (PendingOwnerStorage storage s);

Returns:

Property	Type	Description
s	PendingOwnerStorage storage	The pending-owner struct in diamond storage.

---

transferOwnership

Requires msg.sender == owner; otherwise reverts OwnerUnauthorizedAccount. Sets pendingOwner to _newOwner and emits OwnershipTransferStarted(owner, _newOwner). Does not change owner until acceptOwnership.

function transferOwnership(address _newOwner);

Parameters:

Property	Type	Description
_newOwner	address	Address that must call acceptOwnership to become owner.

---

acceptOwnership

Requires msg.sender == pendingOwner; otherwise reverts OwnerUnauthorizedAccount. Assigns owner to the pending address, clears pendingOwner, and emits OwnershipTransferred(previousOwner, newOwner).

function acceptOwnership();

Events

Emitted when the current owner calls transferOwnership (pending owner set).

Signature:

event OwnershipTransferStarted(address indexed _previousOwner, address indexed _newOwner);

Emitted when the pending owner calls acceptOwnership and ownership is updated.

Signature:

event OwnershipTransferred(address indexed _previousOwner, address indexed _newOwner);

Errors

Thrown when transferOwnership is called by anyone other than the current owner, or when acceptOwnership is called by anyone other than the pending owner.

Signature:

error OwnerUnauthorizedAccount();

Best Practices

• Expose transferOwnership and acceptOwnership only through vetted external facet entrypoints; confirm _newOwner before initiating.
• Keep the same OwnerStorage / PendingOwnerStorage layout as Owner Two Step Transfer Facet and Owner Two Step Data Module
• owner is shared with OwnerDataMod and single-step owner code at keccak256("erc173.owner").

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Last updated:March 24, 2026