Solana: Changed data size error

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 rest:

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,

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 oru128. 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:

`Rest

use STD :: Convert :: {from, Into};

Struct signed dates (U64);

Impl Signeddates {

FN New (Value: U64) -> Self {

Signed data (Value)

}

FN Get_Value (& Self) -> U64 {

self.0

}

}

Impl from for signed dates {

FN from (Value: U64) -> Self {

Signed data (Value)

}

}

`

Example Usage

Now you can create a signeddates instance and use it withsol_invoke_signed_c:

`Rest

use solana_program :: {{

account_info :: {next_account_info, account info},

EntryPoint,

Program_error :: Programror,

Pubkey :: Pubkey,

};

EntryPoint! (Process_ instruction);

FN Process_ instruction (

_account_info: account info,

Instruction_data: & [U8],

_signing_key_id: & pubkey,

) -> Result <_, Programror> {

Let Signed_Data = Signed Dates :: New (1);

Println! (“Signed Data Value: {}”, signed_data.get_Value ());

// call sol_invoke_signed_c with the signed data

Note (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 malfunction and handling large integers.

• Use from traits to convert betweenu64 and signed dates'.

• When Creating aSigneddatesinstance, Ensure It's Initialized Correctly to Avoid Any Issues.

By Following these Guidelines and Using the Right Data Structures, You Should Be Able to Successully Resolve The "Data Size Error" When working withSol_invoke_signed_c` in your Custom Rust Library for Solana Smart Contracts.

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