SAFE Manager

A central hub for all SAFEs

Smart contract code: GebSafeManager

1. Summary

The SAFE Manager is an abstraction around the SAFEEngine that allows anyone to easily manage their GEB positions.

2. Contract Variables & Functions

Variables

• safeEngine - the address of the SAFEEngine

• safei - auto incrementing nonce

• cdps[safeId: uint256] - mapping between SAFE ids and SAFE

• cdpList[safeId: uint256] - double linked list indicating the previous and next SAFE ids of a provided SAFE

• ownsCDP[cdpId: uint256] - indicates the owner of a SAFE

• collateralTypes[cdpId: uint256] - the collateral type backing the SAFE with id safeId

• firstSAFEID[owner: address] - the first safeId of an owner

• lastSAFEID[owner: address] - the last safeId or an owner

• safeCount[owner: address] - the amount of SAFEs and address has

• safeCan[owner: address, safeId: uint256, allowedAddr: address] - whether an address is allowed to interact with a SAFE

• handlerCan[safeHandler: address, allowedAddr: address] - whether an address is allowed to interact with a SAFE's handler

Data Structures

• List - a struct containing the previous and the next SAFE ids of a specific SAFE. Contains:

  • prev - the previous SAFE id

  • next - the next SAFE id

Functions

• allowSAFE(safe: uint256, usr: address, ok: uint256) - allow an address to interact with a SAFE with a specific id

• allowHandler(usr: address, ok: uint256) - allow an address to interact with a SAFE handler

• openSAFE(collateralType: bytes32, usr: address) - create a new SAFE id and handler

• transferSAFEOwnership(safe: uint256, dst: address) - transfer a SAFE to another address

• modifySAFECollateralization(safe: uint256, deltaCollateral: int256, deltaDebt: int256) - add/remove collateral to and from a SAFE or generate/repay debt

• transferCollateral(safe: uint256, dst: address, wad: uint256) - transfer collateral from a SAFE to another address

• transferInternalCoins(safe: uint256, dst: address, rad: uint256) - transfer SAFEEngine.coinBalance system coins between addresses

• quitSystem(safe: uint256, dst: address) - migrate the SAFE to a destination address

• enterSystem(safe: address, src: uint256) - import a SAFE to the handler owned by an address

• moveSAFE(safeSrc: uint256, safeDst: uint256) - move a position between SAFE handlers

• protectSAFE(safe: uint256, liquidationEngine: address, saviour: address) - choose a SAFESaviour for a SAFE

Events

• AllowSAFE - emitted when allowSafe is called. Contains:

  • sender - the msg.sender

  • safe - the SAFE id

  • usr - the address of the user that is allowed/forbidden from managing the SAFE

  • ok - whether the usr is allowed or not to manage the SAFE

• AllowHandler - emitted when allowHandler is called. Contains:

  • sender - the msg.sender

  • usr - the handler

  • ok - whether it is allowed or not

• TransferSAFEOwnership - emitted when transferSAFEOwnership is called. Contains:

  • sender - the msg.sender

  • safe - the SAFE id

  • dst - the new owner

• OpenSAFE - emitted when a new SAFE is created using openSAFE. Contains:

  • sender - the msg.sender

  • own - the SAFE owner

  • safe - SAFE id

• ModifySAFECollateralization - emitted when modifySAFECollateralization is called. Contains:

  • sender - the msg.sender

  • safe - the SAFE id

  • deltaCollateral - the amount of collateral to add/remove

  • deltaDebt - the amount of debt to repay/withdraw

• TransferCollateral - emitted when transferCollateral is called. Contains:

  • sender - the msg.sender

  • safe - the SAFE id

  • dst - the destination SAFE id

  • wad - amount of collateral to transfer

• TransferInternalCoins - emitted when transferInternalCoins is called. Contains:

  • sender - the msg.sender

  • safe - the SAFE id

  • dst - destination for internal coins

  • rad - amount of internal coins to transfer

• QuitSystem - emitted when quitSystem is called. Contains:

  • sender - the msg.sender

  • safe - the SAFE id

  • dst - the destination handler for the SAFE

• EnterSystem - emitted when enterSystem is called. Contains:

  • sender - the msg.sender

  • src - the source handler for the SAFE

  • safe - the SAFE id

• MoveSAFE - emitted when moveSAFE is called. Contains:

  • safe - the SAFE id

  • safeSrc - the source ID that has the current handler controlling the SAFE

  • safeDst - the destination SAFE id that has the handler which will control the safe from now on

• ProtectSAFE - emitted when protectSAFE is called. Contains:

  • sender - the msg.sender

  • safe - the SAFE id

  • liquidationEngine - the LiquidationEngine where saviour is and that can liquidate safe

  • saviour - the saviour that will protect the SAFE

3. Risks

When openSAFE is executed, a new safeHandler is created and a safeId is assigned to it for a specific owner. If the user calls CollateralJoin.join to add collateral to the safeHandler immediately after the SAFE creation transaction is mined, there is a chance that a chain reorg occurs. This would result in the user losing the ownership of the safeHandler and therefore lose their collateral. Users can avoid this issue when using proxy actions.