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Refactor SafeMath to avoid memory leaks #2462

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merged 16 commits into from
Jan 18, 2021

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Amxx
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@Amxx Amxx commented Jan 8, 2021

FIxes #2413, remove the string allocation in SafeMath default functions: caused unrecovered memory allocation even for successfull calls

FIxes OpenZeppelin#2413, remove the string allocation in SafeMath  default functions: caused unrecovered memory allocation even for successfull calls
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frangio commented Jan 11, 2021

After discussing offline we agreed on the following:

  • We will deprecate the existing functions like sub(uint, uint, string) because they leak memory. (This is adding a comment in the source code and in the release notes.)
  • We will implement sub(uint, uint) by directly calling require so it does not leak memory.
  • We will add a new family of functions that return a pair (bool, uint) that can be used to protect against overflow with custom revert reasons, and use these internally in the library. The name for these functions is TBD.

(This also implies that the new add(uint, uint, string) and mul(uint, uint, string) functions added in this PR should be removed.)

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We have to add the same deprecation notice for EnumerableMap.get. We use it in ERC721.ownerOf so while we're at it we should probably change that too.

CHANGELOG.md Outdated Show resolved Hide resolved
CHANGELOG.md Outdated Show resolved Hide resolved
contracts/math/SafeMath.sol Outdated Show resolved Hide resolved
contracts/math/SafeMath.sol Outdated Show resolved Hide resolved
contracts/math/SafeMath.sol Outdated Show resolved Hide resolved
contracts/math/SafeMath.sol Show resolved Hide resolved
test/math/SafeMath.test.js Outdated Show resolved Hide resolved
Amxx and others added 8 commits January 16, 2021 00:46
Co-authored-by: Francisco Giordano <frangio.1@gmail.com>
Co-authored-by: Francisco Giordano <frangio.1@gmail.com>
Co-authored-by: Francisco Giordano <frangio.1@gmail.com>
Co-authored-by: Francisco Giordano <frangio.1@gmail.com>
Co-authored-by: Francisco Giordano <frangio.1@gmail.com>
Co-authored-by: Francisco Giordano <frangio.1@gmail.com>
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Awesome work thanks!

@frangio frangio merged commit c342114 into OpenZeppelin:master Jan 18, 2021
@Amxx Amxx deleted the fix/safemathmemory branch January 18, 2021 22:29
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The SafeMath.div function needlessly allocates memory
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