81 lines
2.9 KiB
Solidity
81 lines
2.9 KiB
Solidity
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// SPDX-License-Identifier: MIT
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pragma solidity ^0.6.0;
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import "./Proxy.sol";
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import "../utils/Address.sol";
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/**
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* @dev This contract implements an upgradeable proxy. It is upgradeable because calls are delegated to an
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* implementation address that can be changed. This address is stored in storage in the location specified by
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* https://eips.ethereum.org/EIPS/eip-1967[EIP1967], so that it doesn't conflict with the storage layout of the
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* implementation behind the proxy.
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*
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* Upgradeability is only provided internally through {_upgradeTo}. For an externally upgradeable proxy see
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* {TransparentUpgradeableProxy}.
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*/
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contract UpgradeableProxy is Proxy {
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/**
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* @dev Initializes the upgradeable proxy with an initial implementation specified by `_logic`.
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*
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* If `_data` is nonempty, it's used as data in a delegate call to `_logic`. This will typically be an encoded
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* function call, and allows initializating the storage of the proxy like a Solidity constructor.
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*/
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constructor(address _logic, bytes memory _data) public payable {
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assert(_IMPLEMENTATION_SLOT == bytes32(uint256(keccak256("eip1967.proxy.implementation")) - 1));
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_setImplementation(_logic);
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if(_data.length > 0) {
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// solhint-disable-next-line avoid-low-level-calls
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(bool success,) = _logic.delegatecall(_data);
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require(success);
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}
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}
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/**
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* @dev Emitted when the implementation is upgraded.
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*/
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event Upgraded(address indexed implementation);
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/**
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* @dev Storage slot with the address of the current implementation.
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* This is the keccak-256 hash of "eip1967.proxy.implementation" subtracted by 1, and is
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* validated in the constructor.
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*/
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bytes32 private constant _IMPLEMENTATION_SLOT = 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc;
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/**
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* @dev Returns the current implementation address.
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*/
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function _implementation() internal override view returns (address impl) {
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bytes32 slot = _IMPLEMENTATION_SLOT;
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// solhint-disable-next-line no-inline-assembly
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assembly {
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impl := sload(slot)
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}
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}
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/**
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* @dev Upgrades the proxy to a new implementation.
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*
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* Emits an {Upgraded} event.
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*/
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function _upgradeTo(address newImplementation) internal {
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_setImplementation(newImplementation);
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emit Upgraded(newImplementation);
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}
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/**
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* @dev Stores a new address in the EIP1967 implementation slot.
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*/
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function _setImplementation(address newImplementation) private {
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require(Address.isContract(newImplementation), "UpgradeableProxy: new implementation is not a contract");
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bytes32 slot = _IMPLEMENTATION_SLOT;
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// solhint-disable-next-line no-inline-assembly
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assembly {
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sstore(slot, newImplementation)
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}
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}
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}
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