ERC-721 Enumeration: Bytecode → Readable Solidity

• Reconstructed a full ERC-721 enumeration loop with our decompiler
• Reads balanceOf, ownerOf
• Preserves the while loop over tokenId <= maxSupply
• Allocates memory safely for the results array
• Renamed supplyLimit to maxSupply for clarity

Original vs Decompiled

function walletOfOwner(address _owner) public view returns (uint256[] memory) {
    uint256 ownerTokenCount = balanceOf(_owner);
    uint256[] memory ownedTokenIds = new uint256[](ownerTokenCount);
    uint256 currentTokenId = 1;
    uint256 ownedTokenIndex = 0;

    while (ownedTokenIndex < ownerTokenCount && currentTokenId <= supplyLimit) {
        address currentTokenOwner = ownerOf(currentTokenId);
        if (currentTokenOwner == _owner) {
            ownedTokenIds[ownedTokenIndex] = currentTokenId;
            ownedTokenIndex++;
        }
        currentTokenId++;
    }

    return ownedTokenIds;
}

function walletOfOwner(address _owner) public view returns (uint256[] memory) {
    uint256 ownerTokenCount = balanceOf(_owner);
    uint256[] memory ownedTokenIds = new uint256[](ownerTokenCount);
    uint256 currentTokenId = 1;
    uint256 ownedTokenIndex = 0;

    while (ownedTokenIndex < ownerTokenCount && currentTokenId <= maxSupply) {
        address currentTokenOwner = ownerOf(currentTokenId);
        if (currentTokenOwner == _owner) {
            ownedTokenIds[ownedTokenIndex] = currentTokenId;
            ownedTokenIndex++;
        }
        currentTokenId++;
    }

    return ownedTokenIds;
}

Why this matters

This pattern is common in NFT projects. Recovering the exact loop bounds, array allocation, and conditional writes is critical for audits because subtle deviations (off-by-one bounds, unchecked owners, or unsafe memory writes) often hide bugs or gas bombs. The output here mirrors the original’s semantics while clarifying naming (maxSupply vs supplyLimit) for readability.

Decompilation approach

• Identify storage slots corresponding to total supply and per-owner balances
• Lift jumps to structured control flow to rebuild while conditions
• Detect dynamic array allocation via new uint256[](count) patterns
• Resolve ownerOf(tokenId) call sites and equality checks to guard writes

Takeaways

• Readable output speeds audit review and diffing against purported sources
• Semantic renaming improves comprehension without changing behavior
• Bytecode-only contracts can still be meaningfully reviewed for safety