35 lines
1.0 KiB
Solidity
35 lines
1.0 KiB
Solidity
pragma solidity ^0.4.24;
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/**
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* @title Helps contracts guard against reentrancy attacks.
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* @author Remco Bloemen <remco@2π.com>, Eenae <alexey@mixbytes.io>
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* @dev If you mark a function `nonReentrant`, you should also
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* mark it `external`.
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*/
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contract ReentrancyGuard {
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/// @dev counter to allow mutex lock with only one SSTORE operation
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uint256 private _guardCounter;
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constructor() internal {
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// The counter starts at one to prevent changing it from zero to a non-zero
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// value, which is a more expensive operation.
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_guardCounter = 1;
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}
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/**
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* @dev Prevents a contract from calling itself, directly or indirectly.
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* Calling a `nonReentrant` function from another `nonReentrant`
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* function is not supported. It is possible to prevent this from happening
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* by making the `nonReentrant` function external, and make it call a
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* `private` function that does the actual work.
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*/
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modifier nonReentrant() {
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_guardCounter += 1;
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uint256 localCounter = _guardCounter;
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_;
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require(localCounter == _guardCounter);
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}
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}
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