5dfe7215a9
* Initial migration to Solidity 0.6.x - v3.0 first steps (#2063) * Initial migration, missing GSN, 721, 777 and Crowdsales. * Add _beforeTokenOperation and _afterTokenOperation. * Add documentation for hooks. * Add hooks doc * Add missing drafts * Add back ERC721 with hooks * Bring back ERC777 * Notes on hooks * Bring back GSN * Make functions virtual * Make GSN overrides explicit * Fix ERC20Pausable tests * Remove virtual from some view functions * Update linter * Delete examples * Remove unnecessary virtual * Remove roles from Pausable * Remove roles * Remove users of roles * Adapt ERC20 tests * Fix ERC721 tests * Add all ERC721 hooks * Add ERC777 hooks * Fix remaining tests * Bump compiler version * Move 721BurnableMock into mocks directory * Remove _before hooks * Fix tests * Upgrade linter * Put modifiers last * Remove _beforeTokenApproval and _beforeOperatorApproval hooks
56 lines
2.2 KiB
Solidity
56 lines
2.2 KiB
Solidity
pragma solidity ^0.6.0;
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/**
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* @dev Contract module that helps prevent reentrant calls to a function.
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*
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* Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
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* available, which can be applied to functions to make sure there are no nested
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* (reentrant) calls to them.
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*
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* Note that because there is a single `nonReentrant` guard, functions marked as
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* `nonReentrant` may not call one another. This can be worked around by making
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* those functions `private`, and then adding `external` `nonReentrant` entry
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* points to them.
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*
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* TIP: If you would like to learn more about reentrancy and alternative ways
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* to protect against it, check out our blog post
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* https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
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*
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* _Since v2.5.0:_ this module is now much more gas efficient, given net gas
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* metering changes introduced in the Istanbul hardfork.
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*/
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contract ReentrancyGuard {
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bool private _notEntered;
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constructor () internal {
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// Storing an initial non-zero value makes deployment a bit more
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// expensive, but in exchange the refund on every call to nonReentrant
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// will be lower in amount. Since refunds are capped to a percetange of
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// the total transaction's gas, it is best to keep them low in cases
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// like this one, to increase the likelihood of the full refund coming
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// into effect.
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_notEntered = true;
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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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// On the first call to nonReentrant, _notEntered will be true
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require(_notEntered, "ReentrancyGuard: reentrant call");
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// Any calls to nonReentrant after this point will fail
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_notEntered = false;
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_;
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// By storing the original value once again, a refund is triggered (see
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// https://eips.ethereum.org/EIPS/eip-2200)
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_notEntered = true;
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}
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}
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