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73 changes: 73 additions & 0 deletions src/utils/CustomRevertDecoder.sol
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//SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

/// @title CurrencyLibrary
/// @notice Decodes arbitrary revert strings from the CustomRevert library
library CustomRevertDecoder {
/// @notice Decodes a revert string from the CustomRevert library
/// @param err the revert string returned by CustomRevert.bubbleUpAndRevertWith
/// @return wrappedErrorSelector the selector of the wrapped error, typically CustomRevert.WrappedError.selector
/// @return revertingContract the address of the contract that reverted
/// @return revertingFunctionSelector the selector of the function that reverted
/// @return revertReasonSelector the selector of the revert reason
/// @return revertReason the revert reason, typically abi.encodeWithSelector(revertReasonSelector, reasonData)
/// @return additionalContextSelector the selector of the additional contextual revert
function decode(bytes memory err)
internal
pure
returns (
bytes4 wrappedErrorSelector,
address revertingContract,
bytes4 revertingFunctionSelector,
bytes4 revertReasonSelector,
bytes memory revertReason,
bytes4 additionalContextSelector,
bytes memory additionalContextReason
)
{
assembly {
wrappedErrorSelector := mload(add(err, 0x20))
revertingContract := mload(add(err, 0x24))
revertingFunctionSelector := mload(add(err, 0x44))

let offsetRevertReason := mload(add(err, 0x64))
let offsetAdditionalContext := mload(add(err, 0x84))
let sizeRevertReason := mload(add(err, add(offsetRevertReason, 0x24)))
let sizeAdditionalContext := mload(add(err, add(offsetAdditionalContext, 0x24)))

revertReasonSelector := mload(add(err, add(offsetRevertReason, 0x44)))
additionalContextSelector := mload(add(err, add(offsetAdditionalContext, 0x44)))

// Decode the revert reason
let ptr := mload(0x40)
revertReason := ptr
mstore(revertReason, sizeRevertReason)

let w := not(0x1f)

for { let s := and(add(sizeRevertReason, 0x20), w) } 1 {} {
mstore(add(revertReason, s), mload(add(err, add(offsetRevertReason, add(0x24, s)))))
s := add(s, w)
if iszero(s) { break }
}

mstore(0x40, add(ptr, add(0x20, sizeRevertReason)))
// ------

// Decode the additional context
ptr := mload(0x40)
additionalContextReason := ptr
mstore(additionalContextReason, sizeAdditionalContext)

w := not(0x1f)

for { let s := and(add(sizeAdditionalContext, 0x20), w) } 1 {} {
mstore(add(additionalContextReason, s), mload(add(err, add(offsetAdditionalContext, add(0x24, s)))))
s := add(s, w)
if iszero(s) { break }
}

mstore(0x40, add(ptr, add(0x20, sizeAdditionalContext)))
Comment on lines +57 to +70
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@saucepoint saucepoint May 15, 2025

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@clemlak I added support for arbitrary bytes in additionalContext for reverts of the following format:

bytes memory data = abi.encodeWithSelector(
    wrappedErrorSelector,
    revertingContract,
    revertingFunctionSelector,
    abi.encodeWithSelector(revertReasonSelector, reasonData),
    abi.encodeWithSelector(additionalContextSelector, additionalContextData) // <-- additionalContextData
);

I'm reusing your size / looping logic -- is re-using mload(0x40) safe? what about the 0x24 magic-offset?

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@gretzke gretzke May 16, 2025

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when you encode the additional context data you have to make sure it's encoded properly. Because you can't just use abi.encodeWithSelector(selector,abi.encode(uint256,bytes)) for example, as the encoded result of abi.encodeWithSelector(selector,uint256,bytes) would be different.

}
}
}
206 changes: 206 additions & 0 deletions test/utils/CustomRevertDecoder.t.sol
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//SPDX-License-Identifier: MIT
pragma solidity ^0.8.24;

import {Test} from "forge-std/Test.sol";
import {IPoolManager} from "@uniswap/v4-core/src/interfaces/IPoolManager.sol";
import {IHooks} from "@uniswap/v4-core/src/interfaces/IHooks.sol";
import {LPFeeLibrary} from "@uniswap/v4-core/src/libraries/LPFeeLibrary.sol";
import {Hooks} from "@uniswap/v4-core/src/libraries/Hooks.sol";
import {CurrencyLibrary} from "@uniswap/v4-core/src/types/Currency.sol";
import {CustomRevert} from "@uniswap/v4-core/src/libraries/CustomRevert.sol";

import {CustomRevertDecoder} from "../../src/utils/CustomRevertDecoder.sol";

contract CustomRevertDecoderTest is Test {
function setUp() public {}

function test_fuzz_decode_customRevert(
bytes4 wrappedErrorSelector,
address revertingContract,
bytes4 revertingFunctionSelector,
bytes4 revertReasonSelector,
bytes memory reasonData,
bytes4 additionalContextSelector,
bytes memory additionalContextData
) public pure {
bytes4 _decodedWrapSelector;
address _decodedRevertingContract;
bytes4 _decodedRevertingFunctionSelector;
bytes4 _decodedRevertReasonSelector;
bytes memory _decodedReason;
bytes4 _decodedAdditionalContextSelector;
bytes memory _decodedAdditionalContextReason;

// scoped to avoid stack too deep error
{
bytes memory data = abi.encodeWithSelector(
wrappedErrorSelector,
revertingContract,
revertingFunctionSelector,
abi.encodeWithSelector(revertReasonSelector, reasonData),
abi.encodeWithSelector(additionalContextSelector, additionalContextData)
);

(
_decodedWrapSelector,
_decodedRevertingContract,
_decodedRevertingFunctionSelector,
_decodedRevertReasonSelector,
_decodedReason,
_decodedAdditionalContextSelector,
_decodedAdditionalContextReason
) = CustomRevertDecoder.decode(data);
}

assertEq(_decodedWrapSelector, wrappedErrorSelector);
assertEq(_decodedRevertingContract, revertingContract);
assertEq(_decodedRevertingFunctionSelector, revertingFunctionSelector);
assertEq(_decodedRevertReasonSelector, revertReasonSelector);
assertEq(_decodedReason, abi.encodeWithSelector(revertReasonSelector, reasonData));
assertEq(_decodedAdditionalContextSelector, additionalContextSelector);
assertEq(
_decodedAdditionalContextReason, abi.encodeWithSelector(additionalContextSelector, additionalContextData)
);
}

function test_decode_empty() public pure {
bytes4 wrappedErrorSelector = CustomRevert.WrappedError.selector;
address revertingContract = address(0x1111);
bytes4 revertingFunctionSelector = bytes4(0);
bytes4 revertReasonSelector = bytes4(0);
bytes4 additionalContextSelector = CurrencyLibrary.NativeTransferFailed.selector;

bytes memory data = abi.encodeWithSelector(
wrappedErrorSelector,
revertingContract,
revertingFunctionSelector,
abi.encodeWithSelector(revertReasonSelector),
abi.encodeWithSelector(additionalContextSelector)
);

(
bytes4 _decodedWrapSelector,
address _decodedRevertingContract,
bytes4 _decodedRevertingFunctionSelector,
bytes4 _decodedRevertReasonSelector,
bytes memory _decodedReason,
bytes4 _decodedAdditionalContextSelector,
bytes memory _decodedAdditionalContextReason
) = CustomRevertDecoder.decode(data);

// assert original values against decoded values
assertEq(_decodedWrapSelector, wrappedErrorSelector);
assertEq(_decodedRevertingContract, revertingContract);
assertEq(_decodedRevertingFunctionSelector, revertingFunctionSelector);
assertEq(_decodedRevertReasonSelector, revertReasonSelector);
assertEq(_decodedReason, abi.encodeWithSelector(revertReasonSelector));
assertEq(_decodedAdditionalContextSelector, additionalContextSelector);
assertEq(_decodedAdditionalContextReason, abi.encodeWithSelector(additionalContextSelector));
}

function test_decode_singleParameter() public pure {
bytes4 wrappedErrorSelector = CustomRevert.WrappedError.selector;
address revertingContract = address(0x1111);
bytes4 revertingFunctionSelector = IHooks.afterInitialize.selector;
bytes4 revertReasonSelector = LPFeeLibrary.LPFeeTooLarge.selector;
uint24 reasonData = uint24(10000);
bytes4 additionalContextSelector = Hooks.HookCallFailed.selector;

bytes memory data = abi.encodeWithSelector(
wrappedErrorSelector,
revertingContract,
revertingFunctionSelector,
abi.encodeWithSelector(revertReasonSelector, reasonData),
abi.encodeWithSelector(additionalContextSelector)
);

(
bytes4 _decodedWrapSelector,
address _decodedRevertingContract,
bytes4 _decodedRevertingFunctionSelector,
bytes4 _decodedRevertReasonSelector,
bytes memory _decodedRevertReason,
bytes4 _decodedAdditionalContextSelector,
bytes memory _decodedAdditionalContextReason
) = CustomRevertDecoder.decode(data);

// assert original values against decoded values
assertEq(_decodedWrapSelector, wrappedErrorSelector);
assertEq(_decodedRevertingContract, revertingContract);
assertEq(_decodedRevertingFunctionSelector, revertingFunctionSelector);
assertEq(_decodedRevertReasonSelector, revertReasonSelector);
assertEq(_decodedRevertReason, abi.encodeWithSelector(revertReasonSelector, reasonData));
assertEq(_decodedAdditionalContextSelector, additionalContextSelector);
assertEq(_decodedAdditionalContextReason, abi.encodeWithSelector(additionalContextSelector));
}

function test_decode_norevertReasonSelector() public pure {
bytes4 wrappedErrorSelector = CustomRevert.WrappedError.selector;
address revertingContract = address(0x1111);
bytes4 revertingFunctionSelector = IHooks.afterInitialize.selector;
bytes32 reason = bytes32(0);
bytes4 additionalContextSelector = CurrencyLibrary.ERC20TransferFailed.selector;

bytes memory data = abi.encodeWithSelector(
wrappedErrorSelector,
revertingContract,
revertingFunctionSelector,
abi.encode(reason),
abi.encodeWithSelector(additionalContextSelector)
);

(
bytes4 _decodedWrapSelector,
address _decodedRevertingContract,
bytes4 _decodedRevertingFunctionSelector,
bytes4 _decodedRevertReasonSelector,
bytes memory _decodedReason,
bytes4 _decodedAdditionalContextSelector,
bytes memory _decodedAdditionalContextReason
) = CustomRevertDecoder.decode(data);

// assert original values against decoded values
assertEq(_decodedWrapSelector, wrappedErrorSelector);
assertEq(_decodedRevertingContract, revertingContract);
assertEq(_decodedRevertingFunctionSelector, revertingFunctionSelector);
assertEq(_decodedRevertReasonSelector, bytes4(0));
assertEq(_decodedReason, abi.encode(reason));
assertEq(_decodedAdditionalContextSelector, additionalContextSelector);
assertEq(_decodedAdditionalContextReason, abi.encodeWithSelector(additionalContextSelector));
}

function test_decode_noReason() public pure {
bytes4 wrappedErrorSelector = CustomRevert.WrappedError.selector;
address revertingContract = address(0x1111);
bytes4 revertingFunctionSelector = IHooks.afterInitialize.selector;
bytes4 revertReasonSelector = IPoolManager.UnauthorizedDynamicLPFeeUpdate.selector;
bytes4 additionalContextSelector = Hooks.HookCallFailed.selector;

bytes memory data = abi.encodeWithSelector(
wrappedErrorSelector,
revertingContract,
revertingFunctionSelector,
abi.encodeWithSelector(revertReasonSelector),
abi.encodeWithSelector(additionalContextSelector)
);

(
bytes4 _decodedWrapSelector,
address _decodedRevertingContract,
bytes4 _decodedRevertingFunctionSelector,
bytes4 _decodedRevertReasonSelector,
bytes memory _decodedReason,
bytes4 _decodedAdditionalContextSelector,
bytes memory _decodedAdditionalContextReason
) = CustomRevertDecoder.decode(data);

// assert original values against decoded values
assertEq(_decodedWrapSelector, wrappedErrorSelector);
assertEq(_decodedRevertingContract, revertingContract);
assertEq(_decodedRevertingFunctionSelector, revertingFunctionSelector);
assertEq(_decodedRevertReasonSelector, revertReasonSelector);
assertEq(_decodedReason, abi.encodeWithSelector(revertReasonSelector));
assertEq(_decodedAdditionalContextSelector, additionalContextSelector);
assertEq(_decodedAdditionalContextReason, abi.encodeWithSelector(additionalContextSelector));
}
}