# Piggy Bank (Native) This program will create a PDA to store SOL. SOL is kept in this PDA until expiry. After expiry, SOL can be sent to a designated account. Complete all tasks below - Implement the piggy bank program - Test locally with LiteSVM - Deploy locally to `solana-test-validator` and test with Rust script # Task 1 - Implement [`instructions::lock`](https://github.com/Cyfrin/solana-course/blob/main/apps/piggy/native/exercise/src/instructions/lock.rs) - Check dst signed, verifies dst exists and approved to later receive SOL ```rust if !dst.is_signer { return Err(ProgramError::MissingRequiredSignature); } ``` - Check that the given account key matches expected PDA ```rust if *pda.key != get_pda(program_id, payer.key, &dst, bump)? { return Err(ProgramError::InvalidSeeds); } ``` - Check `amt` > 0 - Verify expiration `exp` is in the future - Create PDA account ```rust invoke_signed( &system_instruction::create_account( payer.key, pda.key, rent, space as u64, program_id, ), &[payer.clone(), pda.clone(), sys_program.clone()], &[&[b"lock", payer.key.as_ref(), dst.as_ref(), &[bump]]], )?; ``` - Transfer SOL from `payer` to PDA ```rust invoke( &system_instruction::transfer(payer.key, pda.key, amt), &[payer.clone(), pda.clone(), sys_program.clone()], )?; ``` - Create and save `Lock` state into PDA data ```rust let mut data = pda.data.borrow_mut(); let lock = Lock { dst, exp }; lock.serialize(&mut &mut data[..])?; ``` - Call `instructions::lock` inside `lib.rs` # Task 2 - Implement [`instructions::unlock`](https://github.com/Cyfrin/solana-course/blob/main/apps/piggy/native/exercise/src/instructions/unlock.rs) - Check that the given account key matches expected PDA - Load lock state ```rust let (lock_dst, lock_exp) = { let data = pda.data.borrow(); let lock = Lock::try_from_slice(&data)?; (lock.dst, lock.exp) }; // Drop borrow here ``` - Verify destination matches - Verify lock has expired - Get PDA balance and transfer lamports directly ```rust **pda.try_borrow_mut_lamports()? = 0; **dst.try_borrow_mut_lamports()? = dst .lamports() .checked_add(pda_lamports) .ok_or(ProgramError::ArithmeticOverflow)?; ``` - Clear out data ```rust pda.resize(0)?; ``` - Assign the account to the System Program ```rust pda.assign(sys_program.key); ``` - Call `instructions::unlock` inside `lib.rs` # Build ```shell cargo build-sbf ``` # Test ```shell cargo test -- --nocapture ``` # Test with script Run local validator ```shell solana config set -ul solana-test-validator ``` Deploy program ```shell solana program deploy ./target/deploy/piggy.so ``` Execute demo script ```shell PROGRAM_ID=your program ID RPC=http://localhost:8899 KEYPAIR=path to key pair cargo run --example demo $KEYPAIR $RPC $PROGRAM_ID ```