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@0x/zero-ex: Always offset storage bucket ID by 1. (#2579)

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Co-authored-by: Lawrence Forman <me@merklejerk.com>
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Lawrence Forman 2020-05-08 20:13:45 -04:00 committed by GitHub
parent ff1811ef90
commit b348084e2a
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4 changed files with 17 additions and 17 deletions
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4
contracts/zero-ex/contracts/src/storage/LibOwnableStorage.sol
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@ -33,9 +33,9 @@ library LibOwnableStorage {
/// @dev Get the storage bucket for this contract. /// @dev Get the storage bucket for this contract.
function getStorage() internal pure returns (Storage storage stor) { function getStorage() internal pure returns (Storage storage stor) {
uint256 storageOffset = LibStorage.getStorageOffset( uint256 storageSlot = LibStorage.getStorageSlot(
LibStorage.StorageId.Ownable LibStorage.StorageId.Ownable
); );
assembly { stor_slot := storageOffset } assembly { stor_slot := storageSlot }
} }
} }

4
contracts/zero-ex/contracts/src/storage/LibProxyStorage.sol
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@ -33,9 +33,9 @@ library LibProxyStorage {
/// @dev Get the storage bucket for this contract. /// @dev Get the storage bucket for this contract.
function getStorage() internal pure returns (Storage storage stor) { function getStorage() internal pure returns (Storage storage stor) {
uint256 storageOffset = LibStorage.getStorageOffset( uint256 storageSlot = LibStorage.getStorageSlot(
LibStorage.StorageId.Proxy LibStorage.StorageId.Proxy
); );
assembly { stor_slot := storageOffset } assembly { stor_slot := storageSlot }
} }
} }

4
contracts/zero-ex/contracts/src/storage/LibSimpleFunctionRegistryStorage.sol
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@ -33,9 +33,9 @@ library LibSimpleFunctionRegistryStorage {
/// @dev Get the storage bucket for this contract. /// @dev Get the storage bucket for this contract.
function getStorage() internal pure returns (Storage storage stor) { function getStorage() internal pure returns (Storage storage stor) {
uint256 storageOffset = LibStorage.getStorageOffset( uint256 storageSlot = LibStorage.getStorageSlot(
LibStorage.StorageId.SimpleFunctionRegistry LibStorage.StorageId.SimpleFunctionRegistry
); );
assembly { stor_slot := storageOffset } assembly { stor_slot := storageSlot }
} }
} }

22
contracts/zero-ex/contracts/src/storage/LibStorage.sol
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@ -23,29 +23,29 @@ pragma experimental ABIEncoderV2;
/// @dev Common storage helpers /// @dev Common storage helpers
library LibStorage { library LibStorage {
/// @dev What to multiply a storage ID by to get its offset. /// @dev What to bit-shift a storage ID by to get its slot.
/// This is also the maximum number of fields inside a storage /// This gives us a maximum of 2**128 inline fields in each bucket.
/// bucket. uint256 private constant STORAGE_SLOT_EXP = 128;
uint256 internal constant STORAGE_OFFSET_MULTIPLIER = 1e18;
/// @dev Storage IDs for feature storage buckets. /// @dev Storage IDs for feature storage buckets.
enum StorageId { enum StorageId {
Unused, // Unused buffer for state accidents.
Proxy, Proxy,
SimpleFunctionRegistry, SimpleFunctionRegistry,
Ownable Ownable
} }
/// @dev Get the storage offset given a storage ID. /// @dev Get the storage slot given a storage ID. We assign unique, well-spaced
/// slots to storage bucket variables to ensure they do not overlap.
/// See: https://solidity.readthedocs.io/en/v0.6.6/assembly.html#access-to-external-variables-functions-and-libraries
/// @param storageId An entry in `StorageId` /// @param storageId An entry in `StorageId`
/// @return offset The storage offset. /// @return slot The storage slot.
function getStorageOffset(StorageId storageId) function getStorageSlot(StorageId storageId)
internal internal
pure pure
returns (uint256 offset) returns (uint256 slot)
{ {
// This should never overflow with a reasonable `STORAGE_OFFSET_MULTIPLIER` // This should never overflow with a reasonable `STORAGE_SLOT_EXP`
// because Solidity will do a range check on `storageId` during the cast. // because Solidity will do a range check on `storageId` during the cast.
return uint256(storageId) * STORAGE_OFFSET_MULTIPLIER; return (uint256(storageId) + 1) << STORAGE_SLOT_EXP;
} }
} }