Passing PDA seeds and bump to sol_invoke_signed_c syscall in solana_nostd_entrypoint environment: missing required signature for instruction

Question

Before: There seemed to be a lack of solana nostd entrypoint documentation, I couldn't find any good resources.

I made solana program using solana_nostd_entrypoint. I want to create PDA account using InstructionC.

        let rent = solana_program::rent::Rent::default();
        let space = 1000;
        let rent_lamports = rent.minimum_balance(space);

        let mut instruction_data = [0u8; 56];
        instruction_data[4..12].copy_from_slice(&rent_lamports.to_le_bytes());
        instruction_data[12..20].copy_from_slice(&space.to_le_bytes());
        instruction_data[20..52].copy_from_slice(program_id.as_ref());
        let instruction_accounts = [signer.to_meta_c(), game_pda.to_meta_c()];

        let instruction = InstructionC {
            program_id: &system_program::ID,
            accounts: instruction_accounts.as_ptr(),
            accounts_len: instruction_accounts.len() as u64,
            data: instruction_data.as_ptr(),
            data_len: instruction_data.len() as u64,
        };
        let infos = [signer.to_info_c(), game_pda.to_info_c()];
        let seeds: &[&[&[u8]]] = &[&[GAME_PDA, &[GAME_PDA_BUMP]]];
        #[cfg(target_os = "solana")]
        unsafe {
            solana_program::syscalls::sol_invoke_signed_c(
                &instruction as *const InstructionC as *const u8,
                infos.as_ptr() as *const u8,
                infos.len() as u64,
                seeds.as_ptr() as *const u8,
                seeds.len() as u64,
            );
        }

But sol_invoke_signed_c fails because of lack of pda signature. Error log:

transactionLogs: [
    'Program ProgramID invoke [1]',
    'Program 11111111111111111111111111111111 invoke [2]',
    "Allocate: 'to' account Address { address: PDA account here, base: None } must sign",
    'Program 11111111111111111111111111111111 failed: missing required signature for instruction',
    'Program ProgramID  consumed 1555 of 200000 compute units',
    'Program ProgramID  failed: missing required signature for instruction'
  ]

Am I wrong to pass pda seeds and bump to sol_invoke_signed_c syscall cpi?

How can I fix this error?

Answer 1

There's a specialized function for converting PDAs into an account meta usable for CPI: to_meta_c_signer https://github.com/cavemanloverboy/solana-nostd-entrypoint/blob/59856f0fd551845080482d64235914a0c4c7341a/solana-nostd-entrypoint/src/entrypoint_nostd.rs#L622

Try changing your code to:

        let instruction_accounts = [signer.to_meta_c(), game_pda.to_meta_c_signer()];