Questions tagged [contract-debugging]
questions for finding and squashing bugs in smart contracts and decentralized development
464
questions
1
vote
1answer
20 views
Getting an 'invalid opcode' calling a solidty function from test file
im in the process of learning about ethereum and Solidity, and im having a problem calling a payable function from a test file.
This is my contract
pragma solidity >=0.4.22 <0.6.0;
//pragma ...
3
votes
3answers
34 views
Revising Smart Contracts [closed]
If I create a Smart Contract that pays users for sharing their data, how can I ever update this smart contract in the case it has an error, or perhaps I wish to change the amount paid for data sharing?...
1
vote
1answer
29 views
Cannot transfer ownership of ERC20 contract
My contract source code likes below:
contract StandardToken
{
uint256 totalSupply;
...
}
contract Ownable {
address public owner;
function Ownable() public {
owner = msg.sender;
}
...
0
votes
1answer
16 views
Why does declaring returns type bytes memory give a compiler error?
If we have the following code:
pragma solidity >= 0.5;
contract stringsContract {
function takesTwo(string memory str, uint idx) public pure returns (bytes memory) {
bytes memory ...
0
votes
1answer
34 views
Remix IDE: How to debug a contract having a function with a argument & for Loop
I am trying to debug a contract on Remix IDE:
pragma solidity ^0.5.1;
contract DebuggerSampleContract{
int counter = 10;
function LoopCounter(int _input) public view returns (int) {
int ...
0
votes
0answers
16 views
Sample Contracts for Testing Static Analysis Tools
I have to analyse some static Analysis tools against well documented vulnerabilities. My questions are ;
Can we use the provided sample contracts (in above link) directly or not ?
If not, then where ...
0
votes
1answer
32 views
VM error: revert.The called function should be payable if you send value and the value you send should be less than your current balance
There is already a similar question, but it doesn't help me. So I ask this question again and expect something useful information.
Two contracts named AccessControl.sol and Judge.sol. I've removed ...
1
vote
2answers
43 views
Install Old Solc Compiler Versions
I would like to compile older versions of solc contract source code using a solc compiler on my local machine. Is there a website from which to download old solc compilers?
Google revealed a GitHub ...
2
votes
0answers
20 views
Address to create a contract
This query is for informational purposes, with something that has had me in doubt all night.
I am trying to send a self-signed transaction for the creation of a contract
My Tx transaction to send is
...
2
votes
1answer
27 views
Solidity. Find whether a key exists in a mapping. Then get its value
I have a simple mapping:
mapping(address => string) professorsExam;
How can I check if msg.sender is a key in this mapping, and if it is, get its value? If it isn't I should return something.
...
0
votes
0answers
15 views
Backward program analysis (like symbolic backward execution) tools for smart contracts
I know there are some backward program analysis tools for traditional softwares, but i wonder if there are already backward symbolic execution tools for smart contracts, or any tool that I can refer ...
0
votes
1answer
40 views
Solidity - Creating child contract
Recent code:
pragma solidity ^0.5.11;
pragma experimental ABIEncoderV2;
contract Master {
address Pi_C_Owner;
address payable public NewAuctionPayable; //Hilfsvariable um ...
0
votes
1answer
52 views
Help me Understand the flow of this smart contract
I have 2 smart contract, below is the implementatin of them :
1)
import "./MaintainableUpgradeabilityProxy.sol";
function _createProxy(address implementation, address serviceRegistry) internal ...
0
votes
1answer
31 views
Adding a payee to a donation contract. Error: Transaction reverted
Disclaimer: I'm a noob when it comes to programming altogether let alone smart contracts.
I refactored this code that was written like three years ago so it could work with solidity 0.5.0. I deployed ...
0
votes
1answer
14 views
How can I debug a my Solidity smart contract with a GUI?
Is there any way to debug a Solidity smart contract with a GUI, like remix?
How can I do it for both testnets and mainnet?
0
votes
1answer
18 views
What are the ways to call a smart contract function during development?
What are the ways to call a smart contract function during development using Truffle simulated VM with a GUI interface (like Remix or EtherScan offer)?
I know I could use CLI options like Truffle ...
0
votes
0answers
13 views
Pulling EVM Bytecode of Contract Address [duplicate]
Is there a way to pull the EVM bytecode of a given contract address? Using Web3 perhaps?
I believe using the web3.eth.Contract command may get access to the contract, but I am specifically looking ...
0
votes
0answers
15 views
Feeding a contract address to echidna
Simple question: Can I use echidna on a contract address? Like in mythril the command I use is myth -v4 analyze -1 -a 0xec410f642db4a2bcc4d7a69bc13b1165ebad3cea. I don't see any supporting ...
1
vote
2answers
221 views
How to check Ethereum smart contract info?
I want to know 3 things:
Is an address a smart contract?
Is this smart contract an ERC20 or ERC721 token?
Is the Solidity code public?
1
vote
1answer
27 views
How to call a function with params and check them
I want to create a smart contract that users can send a number to and receive an amount of ether.
function airdrop(uint val) public payable {
require(airdrop == true);
if (val == 0x31){
...
4
votes
2answers
70 views
Verifying a Token Contract with Interface
I managed to deploy a token contract with interface on Kovan Testnet.
Now I wanted to verify the code. However this is a bigger problem than I thought.
The contract got successfully deployed to: ...
1
vote
0answers
50 views
Cannot execute contract in non-intaractive scripts
I want to deploy and to execute ERC-20 contract on geth with non-interactive scripts. But, it seems that non-interactive scripts and console shows different results.
Enviroment
ubuntu 18.04(docker ...
0
votes
1answer
33 views
I accidentally sent a token to a token contract. Can I get it back? $MWAT [closed]
community!
Instead of transferring my ERC20 token $MWAT (RED PLATFORM) to my wallet, I accidentally sent it to the contract itself
https://etherscan.io/tx/...
0
votes
2answers
66 views
ParserError: Expected pragma, import directive or contract /interface/library definition
In an attempt to compile my ABI and verify my contract, I am getting the following warning: "ParserError: Expected pragma, import directive or contract /interface/library definition" on the first line ...
2
votes
2answers
100 views
Web3 - Access return value of events
I want to get the value that my smart contract returns in javascript.
Here is the contract. (version 0.4.25 - web3 version 1.2)
pragma solidity ^0.4.25;
contract SimpleStorage {
uint public ...
0
votes
0answers
30 views
How to debug a mainnet transaction which uses Delegatecall without running a full node?
I need to debug a transaction which was reverted on mainnet.
The problem with most Debuggers (including remix), is if there’s a ᴅᴇʟᴇɢᴀᴛᴇᴄᴀʟʟ in that case, they don’t attempt to load the target ...
3
votes
1answer
102 views
What is the “pre-commit” scheme to defeat TOD attack?
I am writing to inquire feasible strategies to defeat Transaction Ordering Dependence (TOD) bugs.
I learned from the best practice guideline such that we can use a so-called "pre-committed" scheme ...
2
votes
1answer
52 views
How to trace the line where a tx failed in truffle tests?
I know about 0x's sol-compiler and sol-trace. I used them before and they do exactly what I'm looking for, but these modules bring significant overhead when used with truffle. Check out this file to ...
0
votes
2answers
37 views
what is the transferfrom event signature?
I am currently writing a code that list all types of transactions in a given contract . my plan is to just check for all logs whether the topics[0] == an event signature of a function. and now i am ...
0
votes
1answer
100 views
Sending value to a solidity contract method from web3 results in `Invalid Tuple Value` error
I'm sending values to a solidity 0.5.1 method using web3 and keep getting an invalid Tuple value error.
Here's the relevant contract code:
struct mystruct {
bytes32 id;
string str;
}
...
1
vote
1answer
54 views
Token migration and IDEX smart contract problem
During a recent token migration from token A to token B, a large number of token A were held by a number of people in an IDEX address (where it was ready to trade). The IDEX address is part of a smart ...
0
votes
2answers
18 views
Mappings can not be assigned to error
I am trying to create a dividend function for my token. This is in the first part of the contract for my coin:
mapping (address => uint256) private _SavedDividend;
Here is the constructor code:
...
0
votes
1answer
32 views
The constructor should be payable if you send value. The transaction has been reverted to the initial state
I'm following a LinkedIn course on Solidity and creating a simple contract. Code below:
I'm new to solidity so I'm not sure exactly where I'm going wrong but I get the following error:
Transact to ...
1
vote
1answer
74 views
No matching declaration found after argument-dependent lookup in remix IDE
I'm getting this error in remix:
"TypeError: No matching declaration found after argument-dependent lookup. require(_spender.call.value(msg.value)(_data));
^-----^ "
function approveAndCall(...
0
votes
0answers
31 views
web3j - getter for array of addresses
I have a contract which has a field registry which is an array of addresses, Also have a getter for this field:
function getRegistry() view public returns (address[] memory){
return ...
1
vote
1answer
28 views
Using contract to create Child contracts (web3j Java wrapper)
I have a simple Parent contract that creates child contracts and stores their address.
contract Parent {
address[] public registry;
function createChild () public {
address newChild =...
0
votes
1answer
65 views
Contract function call error “TypeError: Cannot read property 'isMinter' of undefined” using Truffle tool
I deployed a ERC20Mintable token in truffle env(the .sol file is ERC20Mintable.sol).
2_mintable.js
=============
Deploying 'ERC20Mintable'
-------------------------
> transaction hash: ...
0
votes
1answer
20 views
Syntax Error & how pay( ) would execute without explicitly calling pay( )?
I am getting a syntax error in the following code:
pragma solidity ^0.5.1;
contract C {
function pay(uint n, address payable d)public {
d.send(n);
}
}
contract D1 {
uint ...
0
votes
1answer
120 views
How to test the fuctionality of a Bittrex-related smart contract?
I've got my hands on a smart contract related to the Bittrex exchange.
I would like to deploy this smart contract to test the functionality but I don't know how to call the functions properly. My ...
0
votes
1answer
45 views
truffle won't run tests while initializing a global contract instance
I am testing my smart contract in truffle. I need to declare some global variables hence I did so outside 'it'.
I also tried declaring a global contract instance that I can use in all test cases.
...
0
votes
0answers
29 views
how much structure variable does solidity support? [duplicate]
Error: "UnimplementedFeatureError: Variable inaccessible, too deep
inside stack"
code:
contract create{
struct s{
string s1;
string s2;
string s3;
string s4;
...
4
votes
3answers
297 views
Handling decimals in somewhat complex math
I'm a bit lost on what to do with the following calculation. The problem is that decimals are being round up/down, which obviously doesn't give me the result I desire.
int totalValue = 275000;
int ...
2
votes
1answer
196 views
Is it normal to have Invalid opcode in a contract?
I was debugging my smart contract, while I did not encounter an invalid opcode error, I saw a lot of invalid opcodes in my deployed contract. Screenshot is from remix debugger. Is it normal to have ...
1
vote
0answers
133 views
why .call() in Truffle did not return results as expected?
I'm deploying a contract to my private chain and try to call the contract's function.
After I got in the geth console and finished deploy contract, I called the function but it doesn't work ...
0
votes
1answer
148 views
dApp index.html fails to load for dAppUniversity election application
Hit a brick wall with this.
git clone https://github.com/dappuniversity/election
The following is the Shell output I get when I npm run dev. I’m using the cloned project from GitHub but I’ve ...
0
votes
1answer
48 views
Deploy Contract Syntax Error
I am testing a contract, when I run the truffle migrate command, in my deplyment contract located in the migrations folder the following error appears:
var HelloWorld=artifacts.require (“./HelloWorld....
0
votes
0answers
86 views
Transaction to Smart Contract runs out of gas on Ropsten but not on Rinkeby
the following execution of my smart contract function runs out of Gas on the Ropsten network, but works fine on Rinkeby, do you have an idea why this happens?
struct vehicleData{
string ...
1
vote
1answer
164 views
Using address.call.value to send ether from contract to contract in 0.5.0 and above
In Solidity v0.4.24 and below, I would send ether from contract to contract using the following code within a bigger function :
if (!_address.call.value(_ether)()){
revert();
}
...
1
vote
1answer
94 views
overflow/underflow issues?
pragma solidity 0.5.1;
contract basics{
using SafeMath for *;
uint time;
address payable sender;
uint amount;
event moneySent(address s,uint a);
mapping(address=>person) ...
0
votes
1answer
29 views
Compile source code error expected pragma
I am getting an error when coding a token with the Ethereum wallet. Namely, Expected pragma, import directive or contract/interface/library definition. function burn (uint256 _value)public returns(...
