Exclude address(0) in ERC721 approvals #4405
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frangio
changed the title
| return (owner != address(0) && | ||
| (spender == owner || | ||
| isApprovedForAll(owner, spender) || | ||
| (_getApproved(tokenId) == spender && spender != address(0)))); |
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No actionnable here, but for the record I'm not a big fan of the linter's style.
| @@ -386,8 +389,12 @@ abstract contract ERC721 is Context, ERC165, IERC721, IERC721Metadata, IERC721Er | |||
| * Emits an {Approval} event. | |||
| */ | |||
| function _approve(address to, uint256 tokenId) internal virtual { | |||
| address owner = ownerOf(tokenId); | |||
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We should note that ownerOf is already called in the public approve.
If we want to minimize duplicated sloads, we could use a construction similar to _update's condition. This function is almost never used though, so optimising it is not as critical as transferFrom.
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Closing in favor of #4377 |
This PR implements a few changes to make the treatment of
address(0)in ERC721 more uniform and consistent with the rest of the library:_isApprovedOrOwner: Ensure we return false ifspenderisaddress(0). Don't revert if the token is not minted.setApprovalForAll: Revert ifoperatorisaddress(0).approve: Revert iftoisaddress(0).The reasoning to reject
address(0)is that it can show up unexpectedly by reading uninitialized values from storage, or any uninitialized variable, or as the return value of ecrecover, etc., and in the case of_isApprovedOrOwnerif the spender isaddress(0)it could cause the function to return true in combination withgetApproved, since that function returns 0 to indicate that no account is approved.Proposing first before writing tests.
Fixes #4136.
Closes #4169 (superceded).
Closes #4144 (superceded).