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setArbitraryStorage

签名

function setArbitraryStorage(address target) external;

描述

实用的作弊代码，使给定地址的存储完全符号化。 任何后续对目标存储的 SLOAD 操作都会读取一个任意值，如果同一槽位再次加载，则返回该值。 如果存储槽位被显式写入（在第一次加载之前或之后），则返回写入的值。

示例

对于具有以下存储布局的合约：

contract Counter {
    address[] public owners;

    function getOwner(uint256 pos) public view returns (address) {
        return owners[pos];
    }

    function setOwner(uint256 pos, address owner) public {
        owners[pos] = owner;
    }
}

使用 setArbitraryStorage 作弊代码确保返回任意值：

contract ArbitraryStorageTest is Test {
    function testArbitraryStorage() public {
        Counter counter = new Counter();
        vm.setArbitraryStorage(address(counter));
        // Next call would fail with array out of bounds without arbitrary storage
        address owner = counter.getOwner(55);
        // Subsequent calls to same slot returns same value
        assertEq(counter.getOwner(55), owner);
        // The new value is returned if explicitly written
        counter.setOwner(55, address(111));
        assertEq(counter.getOwner(55), address(111));
    }
}