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Address.sol

View Source: openzeppelin-solidity/contracts/utils/Address.sol

Address

Collection of functions related to the address type

Functions

isContract

Returns true if account is a contract. [IMPORTANT]

It is unsafe to assume that an address for which this function returns false is an externally-owned account (EOA) and not a contract. Among others, isContract will return false for the following types of addresses:

  • an externally-owned account
  • a contract in construction
  • an address where a contract will be created
  • an address where a contract lived, but was destroyed ====
function isContract(address account) internal view
returns(bool)

Arguments

Name Type Description
account address
Source Code 
function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        assembly {
            size := extcodesize(account)
        }
        return size > 0;
    }

sendValue

Replacement for Solidity's transfer: sends amount wei to recipient, forwarding all available gas and reverting on errors. https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost of certain opcodes, possibly making contracts go over the 2300 gas limit imposed by transfer, making them unable to receive funds via transfer. {sendValue} removes this limitation. https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more]. IMPORTANT: because control is transferred to recipient, care must be taken to not create reentrancy vulnerabilities. Consider using {ReentrancyGuard} or the https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].

function sendValue(address payable recipient, uint256 amount) internal nonpayable

Arguments

Name Type Description
recipient address payable
amount uint256
Source Code 
function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        (bool success, ) = recipient.call{value: amount}("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

functionCall

Performs a Solidity function call using a low level call. A plain call is an unsafe replacement for a function call: use this function instead. If target reverts with a revert reason, it is bubbled up by this function (like regular Solidity function calls). Returns the raw returned data. To convert to the expected return value, use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`]. Requirements:

  • target must be a contract.
  • calling target with data must not revert. Available since v3.1.
function functionCall(address target, bytes data) internal nonpayable
returns(bytes)

Arguments

Name Type Description
target address
data bytes
Source Code 
function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionCall(target, data, "Address: low-level call failed");
    }

functionCall

Same as {xref-Address-functionCall-address-bytes-}[functionCall], but with errorMessage as a fallback revert reason when target reverts. Available since v3.1.

function functionCall(address target, bytes data, string errorMessage) internal nonpayable
returns(bytes)

Arguments

Name Type Description
target address
data bytes
errorMessage string
Source Code 
function functionCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

functionCallWithValue

Same as {xref-Address-functionCall-address-bytes-}[functionCall], but also transferring value wei to target. Requirements:

  • the calling contract must have an ETH balance of at least value.
  • the called Solidity function must be payable. Available since v3.1.
function functionCallWithValue(address target, bytes data, uint256 value) internal nonpayable
returns(bytes)

Arguments

Name Type Description
target address
data bytes
value uint256
Source Code 
function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

functionCallWithValue

Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[functionCallWithValue], but with errorMessage as a fallback revert reason when target reverts. Available since v3.1.

function functionCallWithValue(address target, bytes data, uint256 value, string errorMessage) internal nonpayable
returns(bytes)

Arguments

Name Type Description
target address
data bytes
value uint256
errorMessage string
Source Code 
function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");

        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

functionStaticCall

Same as {xref-Address-functionCall-address-bytes-}[functionCall], but performing a static call. Available since v3.3.

function functionStaticCall(address target, bytes data) internal view
returns(bytes)

Arguments

Name Type Description
target address
data bytes
Source Code 
function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

functionStaticCall

Same as {xref-Address-functionCall-address-bytes-string-}[functionCall], but performing a static call. Available since v3.3.

function functionStaticCall(address target, bytes data, string errorMessage) internal view
returns(bytes)

Arguments

Name Type Description
target address
data bytes
errorMessage string
Source Code 
function functionStaticCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

functionDelegateCall

Same as {xref-Address-functionCall-address-bytes-}[functionCall], but performing a delegate call. Available since v3.4.

function functionDelegateCall(address target, bytes data) internal nonpayable
returns(bytes)

Arguments

Name Type Description
target address
data bytes
Source Code 
function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

functionDelegateCall

Same as {xref-Address-functionCall-address-bytes-string-}[functionCall], but performing a delegate call. Available since v3.4.

function functionDelegateCall(address target, bytes data, string errorMessage) internal nonpayable
returns(bytes)

Arguments

Name Type Description
target address
data bytes
errorMessage string
Source Code 
function functionDelegateCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");

        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

verifyCallResult

Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the revert reason using the provided one. Available since v4.3.

function verifyCallResult(bool success, bytes returndata, string errorMessage) internal pure
returns(bytes)

Arguments

Name Type Description
success bool
returndata bytes
errorMessage string
Source Code 
function verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal pure returns (bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }

Contracts