mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
27 lines
1.5 KiB
Solidity
27 lines
1.5 KiB
Solidity
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contract C {
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function test(bytes memory buf) public view returns (bool same, bool inplaceDecoded) {
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(uint256[] memory arr1, uint256[] memory arr2) = abi.decode(buf, (uint256[],uint256[]));
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assembly {
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// Check whether arr1 and arr2 end up at the same memory location.
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// This used to be the case, if both tail pointers in buf pointed to the
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// same memory region, i.e. this used to be false in the first two, but true
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// in the last three calls below. The desired behaviour is to always get distinct
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// memory regions, i.e. this should be false.
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same := eq(arr1, arr2)
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// Check whether (given the particular tail pointer of 0x40 for arr1 in the calls below)
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// arr1 points to the part of buf containing the encoding of arr1.
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// The position of the encoding of arr1 in buf is at offset 0x20 (length) + 0x40 (tail pointer)
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// of buf.
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// This used to be the case for all the test calls below, whereas now arr1 is always copied
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// from buf to a new memory area. Should always be false.
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inplaceDecoded := eq(arr1, add(buf, 0x60))
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}
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}
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}
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// ----
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// test(bytes): 0x20, 0x80, 0x40, 0x60, 0, 0 -> false, false
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// test(bytes): 0x20, 0xC0, 0x40, 0x80, 1, 0x42, 1, 0x42 -> false, false
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// test(bytes): 0x20, 0x80, 0x40, 0x40, 1, 0x42 -> false, false
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// test(bytes): 0x20, 0x60, 0x40, 0x40, 0 -> false, false
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// test(bytes): 0x20, 0x80, 0x40, 0x40, 1, 0x42 -> false, false
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