2c11ed59fa
* Include Safe Casting Library with complete and exhaustive test-suite. * linting test file. * Typo in SafeCast import statement * Update test/utils/SafeCast.test.js * Rename `castUXX` to `toUintXX` from suggestion * Tackling the quick and easy suggestions regarding error string improvements etc. * typo and changelog update. * Improve SafeCast tests * Update test/utils/SafeCast.test.js * Update test/utils/SafeCast.test.js * incorrect import * add SafeCast to docs site * Update CHANGELOG.md * Update SafeCast.sol
96 lines
3.0 KiB
Solidity
96 lines
3.0 KiB
Solidity
pragma solidity ^0.5.0;
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/**
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* @dev Wrappers over Solidity's uintXX casting operators with added overflow
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* checks.
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*
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* Downcasting from uint256 in Solidity does not revert on overflow. This can
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* easily result in undesired exploitation or bugs, since developers usually
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* assume that overflows raise errors. `SafeCast` restores this intuition by
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* reverting the transaction when such an operation overflows.
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*
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* Using this library instead of the unchecked operations eliminates an entire
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* class of bugs, so it's recommended to use it always.
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*
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* Can be combined with {SafeMath} to extend it to smaller types, by performing
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* all math on `uint256` and then downcasting.
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*/
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library SafeCast {
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/**
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* @dev Returns the downcasted uint128 from uint256, reverting on
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* overflow (when the input is greater than largest uint128).
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*
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* Counterpart to Solidity's `uint128` operator.
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*
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* Requirements:
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*
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* - input must fit into 128 bits
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*/
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function toUint128(uint256 value) internal pure returns (uint128) {
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require(value < 2**128, "SafeCast: value doesn\'t fit in 128 bits");
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return uint128(value);
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}
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/**
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* @dev Returns the downcasted uint64 from uint256, reverting on
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* overflow (when the input is greater than largest uint64).
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*
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* Counterpart to Solidity's `uint64` operator.
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*
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* Requirements:
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*
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* - input must fit into 64 bits
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*/
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function toUint64(uint256 value) internal pure returns (uint64) {
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require(value < 2**64, "SafeCast: value doesn\'t fit in 64 bits");
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return uint64(value);
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}
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/**
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* @dev Returns the downcasted uint32 from uint256, reverting on
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* overflow (when the input is greater than largest uint32).
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*
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* Counterpart to Solidity's `uint32` operator.
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*
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* Requirements:
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*
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* - input must fit into 32 bits
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*/
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function toUint32(uint256 value) internal pure returns (uint32) {
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require(value < 2**32, "SafeCast: value doesn\'t fit in 32 bits");
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return uint32(value);
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}
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/**
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* @dev Returns the downcasted uint16 from uint256, reverting on
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* overflow (when the input is greater than largest uint16).
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*
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* Counterpart to Solidity's `uint16` operator.
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*
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* Requirements:
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*
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* - input must fit into 16 bits
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*/
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function toUint16(uint256 value) internal pure returns (uint16) {
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require(value < 2**16, "SafeCast: value doesn\'t fit in 16 bits");
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return uint16(value);
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}
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/**
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* @dev Returns the downcasted uint8 from uint256, reverting on
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* overflow (when the input is greater than largest uint8).
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*
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* Counterpart to Solidity's `uint8` operator.
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*
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* Requirements:
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*
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* - input must fit into 8 bits.
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*/
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function toUint8(uint256 value) internal pure returns (uint8) {
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require(value < 2**8, "SafeCast: value doesn\'t fit in 8 bits");
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return uint8(value);
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}
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}
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