Questions tagged [calldata]
Questions about the "data" part in a transaction, which can be accessed by "msg.data". web3.eth.getTransaction calls this field "input".
93
questions
0
votes
1answer
14 views
Why does this call to DSProxy fail?
Take these two contracts, both deployed on Kovan and with the source code verified:
DSProxy: 0xa92Bed719071A4d33B0B348513E7e866a6ff6B3F
TargetContract: 0xE3CD2e7a628b57d3e50c5f7B921182f676721bDF
And ...
0
votes
0answers
13 views
Creating several objects in the same transaction (data repetition)
I'm working with genetic algorithms and I need to create a population. Currently I have this function:
/// @notice Create a new individual
function createIndiv(uint _popSize) public{
for(uint i = ...
0
votes
1answer
21 views
Easiest way to call an implementation function from a proxy contract in Remix
I have the following code in my remix.ethereum.org project:
pragma solidity ^0.6.10;
// SPDX-License-Identifier: Unlicensed
import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/...
0
votes
0answers
16 views
Proxy delegation contract doesn't work
I'm trying to make a proxy to make a contract that I can change for an ethereum project. I did what it says here: https://hackernoon.com/how-to-make-smart-contracts-upgradable-2612e771d5a2 but it ...
1
vote
1answer
82 views
Why does retrieving stored data cost so much compared to using calldata in Solidity?
I have a function that I need to pass an arbitrary length array of addresses to. In remix, just calling a function that has an address[] costs around 30k gas for an array of 5 addresses:
function fun(...
0
votes
1answer
30 views
Return multiple values from diferent smart Contracts
I have two contracts. The first contract has a function called get() that returns this values:
uint _value1
address _value2
address _value3
string memory _value4
string memory _value5
uint _value6
...
2
votes
1answer
48 views
Get return value of a low level call
I'd like to get the return value of a low level call.
(bool success, ) = address(0x1234...7890).call{value:0}(callData);
This post discusses a solution that sounds like it should work, but it doesn'...
0
votes
0answers
21 views
Is there a way to know if a Solidity method will revert?
I have some solidity methods in my contract, and when i make a send in web3.js i would like to know if there is a way to know if the functions are going to revert by using call.
Per-example , in ...
0
votes
0answers
56 views
Data location must be “calldata” for parameter in external function,
I'm getting the following error:
Data location must be "calldata" for parameter in external function, but "memory" was given.
for the following function:
function _registerAirline(address ...
0
votes
1answer
37 views
Error with this.balance
pragma solidity 0.5.9;
contract Testing{
function participate()public payable{
uint winner = 9;
require(msg.value == 0.1 ether);
if ( winner==9)
{
...
0
votes
1answer
24 views
When i call a function: Error: Returned error: VM Exception while processing transaction: invalid opcode
I work on Truffle. My contract is A and its function is infoRep(). infoRep() returns some data. Whenever i call the function in Truffle console the below error occurs:
Error: Returned error: VM ...
1
vote
2answers
68 views
Correct syntax for require required
I am getting following error message with require statement:
Error: Wrong argument count for function call: 0 arguments given but
expected 1. This function requires a single bytes argument. Use ""...
2
votes
2answers
93 views
How to generate calldata for a function
I have got as far as generating the method ID for the function:
function transfer(address src, address dst, uint256 amount);
The method ID would be:
bytes4(keccak256("transfer(address,address,...
1
vote
1answer
294 views
Why Remix IDE asks for CallData and what value we have to give? [duplicate]
In my several programs which I ran through remix IDE, I got a CallData text box. I don't know what value I have to give to this Calldata text box. I tried the following:
from: address : "...
2
votes
1answer
288 views
Remix IDE: What is the purpose of Calldata and Transact Tab
I am trying to execute the following code on Remix IDE.
pragma solidity ^0.5.4;
contract GuessTheNumberChallenge {
constructor() public payable {
require(msg.value == 1 ether);
}
...
0
votes
1answer
36 views
How to call function via interface from another contract when calldata type is used
I have declared the following interface:
interface Test {
function airDropMultiple(
address[] calldata recipients,
uint[] calldata tokenAmount
)
external
...
0
votes
2answers
37 views
Mining with additional data
i'm a beginner in using blockchain. Based on my knowledge, there are two ways blocks are created, mining and sending transactions. As there is an explanation to input additional data while sending a ...
0
votes
0answers
25 views
Call Type Explained [duplicate]
I have yet to come across a well explained definition of all the call types in one place.
* One of call
* Callcode
* Delegatecall
* Staticcall
Would be very grateful if someone could explain the ...
1
vote
1answer
172 views
What data is in 'calldataload'?
I want to parse event logs that are generated by the contract shown below, which assigns different sections of calldataload to the 4 Topics, and the Data section, of the event logs.
Topic 0 receives ...
13
votes
1answer
2k views
When should I use calldata and when should I use memory?
I have seen people use both memory and calldata keywords when writing Solidity. Specifically, they are used when declaring function parameters.
When should I use memory and when should I use calldata?...
0
votes
1answer
34 views
How to get the call graph of a mainchain transaction?
Simple question, but I couldn't find the answer.
There are transactions like this one which involve many chained contracts.
But as storage modify the functions being called and calldata doesn t ...
4
votes
1answer
750 views
What is a function selector?
I am reading an article, it says:
To enable deployment on the Ethereum platform, the contract functions
are compiled into EVM bytecode and a piece of code called function
selector is added, ...
0
votes
1answer
551 views
member not found or not visible after argument-dependent lookup in mapping
pragma solidity >=0.4.0 <0.7.0;
contract New{
mapping(address => string) public users;
string name;
address[] public userAddress ;
//string[] public userNames;
...
0
votes
0answers
35 views
Call Arguments? and Explicit call?
I am trying to understand the arguments of the built-in Solidity's (or EVM's: I am not sure) call function. I know it has 4 arguments. I am trying to understand the call function at:
Syntax Error in ...
1
vote
0answers
21 views
Calling private function from external - where are referenced type parameters stored in the end?
Let's assume we have something like:
contract C {
function externalFunction(uint256[] calldata data) external {
privateFunction(data);
}
function privateFunction(uint256[] memory data)...
0
votes
1answer
51 views
pass storage through interface to library
Here is what am i doing:
There is a library, accept storage argument as parameter, then do some math and return the result.
And there is a contract to call the function in the library, and an extra ...
0
votes
2answers
272 views
Unable to make a transaction with Data using Java api ethSendRawTransaction
I am trying to make a transaction between two different accounts using Java. It works perfectly fine as long as I am not using "Data" parameter.
My intent is not to call a smart contract but to make ...
2
votes
1answer
64 views
Understanding first evm word of reference types in assembly
Given the following function:
function getArrayItems(bytes calldata) external returns (
bytes4 _signature,
bytes32 _wutIsThis,
bytes32 _length,
bytes32 _firstItem
) {
assembly {
...
5
votes
1answer
394 views
can anyone help to explain calldataload
In the Solidity documentation, the definition of calldataload is:
calldataload(p) call data starting from position p (32 bytes)
But I am really confused by what is call data. Is the call data of ...
1
vote
0answers
165 views
Proxy contract DELEGATECALL to pass a DYNAMIC array to a function in the target contract
I'm trying to get a Proxy contract to correctly do a delegatecall to a function in another 'target' contract. The problem is, that I need to pass a dynamic array as the parameter to this function.
Q: ...
1
vote
3answers
370 views
Calldata with too many parameters
While reading https://solidity.readthedocs.io/en/v0.4.21/abi-spec.html#abi I was just thinking what happens when calldata contains more parameters/data than the function expects (I know first ...
1
vote
0answers
220 views
How to decode Tx data? Online tool?
Is there a fast way to decode the data returning from a Smart Contract call? I know there are github projects with JS libraries to decode this kind of data (such as https://github.com/ConsenSys/abi-...
asked Jan 23 '19 at 9:28
Juan Ignacio Pérez Sacristán
2,8037 gold badges27 silver badges60 bronze badges
0
votes
1answer
734 views
What is Calldata tag needed when a function has a string parameter?
I'm using:
pragma solidity ^0.5.0;
I have a function as below in my contract:
function test(string a) external{
a="apple";
}
An error shows up saying I need to add "calldata" to the parameter. ...
1
vote
1answer
748 views
Get the input data of a transaction with web3j
How can I retrieve transaction details (including the input data) from a txHash using Web3j?
I tried the following method:
public void buscarHhash(Web3j web3, String txHash) throws IOException {
...
1
vote
1answer
1k views
How to access string arguments from calldata in external functions? (0.5.X)
With the introduction of Solc 0.5.X , parameter memory locations for arrays (and strings/bytes) must be made explicit. For external functions, this memory location is required to be specified as ...
7
votes
1answer
5k views
calldata keyword as parameter in solidity v0.5.0 function?
What purpose does the "calldata" serve in this parameter _owners? Is it a new keyword?
function setup(address[] calldata _owners, uint256 _threshold, address to, bytes calldata data)
Taken from ...
1
vote
2answers
71 views
Thinking through from traditional DB to ETH
I am looking for a data structure kind of like this:
[
"data": {
"id": 0,
"hash" : "5feceb66ffc86f38d952786c6d696c79c2dbc239dd4e91b46729d73a27fb57e9",
"owner" : 0,
"status" : "...
1
vote
2answers
530 views
How calldata is stored in memory?
When I execute this:
bytes8 h = 0x000008dfe2f440000733c;
t.call.gas(0x7e0b0)(bytes4(keccak256("enter(bytes8)")),0x8dfe2f440000733c0000000,h);
the calldata is :
0: ...
2
votes
1answer
322 views
How does a contract's constructor work and load input values?
I set up the following contract:
pragma solidity ^0.4.25;
contract Simplest {
uint x;
constructor(bool _lucky) public {
if (_lucky == true) {
x = 7;
} else {
...
0
votes
1answer
461 views
Solidity: msg.data vs bytes
This is a simple contract that has a function input_data(bytes data) and a simple fallback function that passes msg.data to function input_data.
contract test_input_data{
address owner;
event ...
2
votes
1answer
311 views
Call function by using bytesData. (call.value()())
Assume I have two contracts:
contract A {
function test1() public view returns(bool) {
return false;
}
}
contract B {
function testCall(address addr, data) public view returns(...
0
votes
1answer
720 views
Web3j directly gets string from contract by eth_call
I just have a simple solidity contract:
pragma solidity ^0.4.19;
contract SampleContract {
string value;
function SampleContract() public {
value = "hello world";
}
...
5
votes
2answers
2k views
What is calldata?
What is calldata? I learned that there are three types of memories:
Storage
Memory
Stack
In the Ethereum docs, it says that the function parameters are of type memory by default.
However, I've also ...
1
vote
0answers
103 views
delegatecall for Smart Contract versioning
I've a state variable
address public current;
which stores the address of the latest updated contract. This value can be modified with a function.
Then, I've a function of this kind
function ...
3
votes
2answers
997 views
How does MetaMask's TRANSACTION DATA work? How to interact with smart contracts by only using MetaMask?
I have this source code
pragma solidity ^0.4.21;
// Relevant part of the CaptureTheEther contract.
contract CaptureTheEther {
mapping (address => bytes32) public nicknameOf;
function ...
3
votes
2answers
407 views
Solidity CALL and DELEGATECALL: messages and data format
I have some questions about Solidity CALL and DELEGATECALL. I have already read some related threads (link), but found no answers to my doubts.
1) Is there any difference in performing a CALL to a ...
2
votes
1answer
367 views
Assign metadata to a transaction
How can I append some (extra) data to a transaction that calls a contract method (with given parameters)? The transaction has only one 'data' field which is used to serialize the method call.
If I ...
1
vote
1answer
960 views
How to send data to smart contract?
I have the variable w1_temp, which i need to send to contract
I have the following code:
var W1Temp = require('w1temp')
var Web3 = require('web3')
var web3 = new Web3()
web3.setProvider(new web3....
2
votes
3answers
146 views
Can I send data to non-contract address?
Metamask allows to attach data to any transaction. What happens if I send some data with some ETH to existing non-contract address? Is that data recorded on the blockchain? Can I read it later?
1
vote
1answer
684 views
Contract call from a contract from a contract?
As I understand it, it is possible for a contract to call another contract by using
othercontractaddress.call(gas_amount).value(eth amount)(tx data).
Or in this case sender -> contract A -> ...
