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gas: add unchecked for ConduitController#updateChannel #440

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Merged
merged 2 commits into from
Jun 8, 2022
Merged

gas: add unchecked for ConduitController#updateChannel #440

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gas: add unchecked for ConduitController#updateChannel
mingwatch Jun 8, 2022
85eabe7
Update contracts/conduit/ConduitController.sol
mingwatch Jun 8, 2022
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7 changes: 5 additions & 2 deletions contracts/conduit/ConduitController.sol
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Original file line number Diff line number Diff line change
Expand Up @@ -154,8 +154,11 @@ contract ConduitController is ConduitControllerInterface {
} else if (!isOpen && channelPreviouslyOpen) {
// Set a previously open channel as closed via "swap & pop" method.
// Decrement located index to get the index of the closed channel.
uint256 removedChannelIndex = channelIndexPlusOne - 1;

uint256 removedChannelIndex;
// channelPreviouslyOpen already make sure channelIndexPlusOne > 0
unchecked {
removedChannelIndex = channelIndexPlusOne - 1;
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This looks safe

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To clarify: this is safe.
In this branch, channelPreviouslyOpen must be true, which means that channelIndexPlusOne != 0. Since it has type uint, it must be > 0 therefore safe.

}
// Use length of channels array to determine index of last channel.
uint256 finalChannelIndex = conduitProperties.channels.length - 1;

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