I see what you’re getting at. Here’s an article with some guidance on how to handle the “data size error” when using sol_invoke_signed_c in Rust:
Error Handling: Solana Data Size Error
When building a custom Rust library for Solana smart contracts, one common issue is encountering the “data size error” when calling sol_invoke_signed_c. This error occurs due to Solana’s signature verification requirements.
Understanding the Error
The “data size error” typically arises from incorrect data encoding or decoding. In this context, it happens because Rust’s Vec and other data structures do not support arbitrary-precision integers like those used in Solana.
Solution: Use the Correct Data Structure
To resolve this issue, you need to use a data structure that can store arbitrarily large integers, such as u64 or u128. You can create a custom type that wraps an u64 and provides methods for arithmetic operations.
Here’s an example of how you could define such a type:
use std::convert::{From, Into};
struct SignedData(u64);
impl SignedData {
fn new(value: u64) -> Self {
SignedData(value)
}
fn get_value(&self) -> u64 {
self.0
}
}
impl From for SignedData {
fn from(value: u64) -> Self {
SignedData(value)
}
}
Example Usage
Now you can create a SignedData instance and use it with sol_invoke_signed_c:
use solana_program::{
account_info::{next_account_info, AccountInfo},
entrypoint,
program_error::ProgramError,
pubkey::Pubkey,
};
entrypoint!(process_instruction);
fn process_instruction(
_account_info: AccountInfo,
instruction_data: &[u8],
_signing_key_id: &Pubkey,
) -> Result<_, ProgramError> {
let signed_data = SignedData::new(1);
println!("Signed data value: {}", signed_data.get_value());
// Call sol_invoke_signed_c with the signed data
let (result, result_signer_id) = sol_invoke_signed_c(
instruction_data,
&signed_data,
next_account_info(),
_signing_key_id,
);
Ok(())
}
Best Practices
When working with sol_invoke_signed_c, keep in mind the following best practices:
- Always use the correct data structure for storing and handling large integers.
- Use
Fromtraits to convert betweenu64andSignedData.
- When creating a
SignedDatainstance, ensure it’s initialized correctly to avoid any issues.
By following these guidelines and using the right data structures, you should be able to successfully resolve the “data size error” when working with sol_invoke_signed_c in your custom Rust library for Solana smart contracts.
