aave-protocol/Proxy.sol at e8d020e9752fbd4807a3b55f9cf98a88dcfb674d · aave/aave-...

aave-protocol/Proxy.sol at e8d020e9752fbd4807a3b55f9cf98a88dcfb674d · aave/aave-protocol · GitHub

pragma solidity ^0.5.0;

/** * @title Proxy * @dev Implements delegation of calls to other contracts, with proper * forwarding of return values and bubbling of failures. * It defines a fallback function that delegates all calls to the address * returned by the abstract _implementation() internal function. */ contract Proxy { /** * @dev Fallback function. * Implemented entirely in `_fallback`. */ function() external payable { _fallback(); }

/** * @return The Address of the implementation. */ function _implementation() internal view returns (address);

/** * @dev Delegates execution to an implementation contract. * This is a low level function that doesn't return to its internal call site. * It will return to the external caller whatever the implementation returns. * @param implementation Address to delegate. */ function _delegate(address implementation) internal { //solium-disable-next-line assembly { // Copy msg.data. We take full control of memory in this inline assembly // block because it will not return to Solidity code. We overwrite the // Solidity scratch pad at memory position 0. calldatacopy(0, 0, calldatasize)

// Call the implementation. // out and outsize are 0 because we don't know the size yet. let result := delegatecall(gas, implementation, 0, calldatasize, 0, 0)

// Copy the returned data. returndatacopy(0, 0, returndatasize)

switch result // delegatecall returns 0 on error. case 0 { revert(0, returndatasize) } default { return(0, returndatasize) } } }

/** * @dev Function that is run as the first thing in the fallback function. * Can be redefined in derived contracts to add functionality. * Redefinitions must call super._willFallback(). */ function _willFallback() internal {}

/** * @dev fallback implementation. * Extracted to enable manual triggering. */ function _fallback() internal { _willFallback(); _delegate(_implementation()); } }