Hack the rent exempt bug (#265)

* Hack the rent exempt bug

* Fix compile bug

* Fix account resize potential problem

* Use invoke transfer instead of playing with lamports

Author: ali-behjati

solana/pyth2wormhole/program/src/attest.rs

@@ -22,6 +22,8 @@ use solana_program::{
     program_error::ProgramError,
     pubkey::Pubkey,
     rent::Rent,
+    system_instruction,
+    sysvar::Sysvar as SolanaSysvar,
 };
 
 use p2w_sdk::{
@@ -332,5 +334,42 @@ pub fn attest(ctx: &ExecutionContext, accs: &mut Attest, data: AttestData) -> So
         .as_slice(),
     )?;
 
+    // NOTE: 2022-09-05
+    //
+    // This part is added to avoid rent exemption error that is introduced using
+    // a wrong implementation in solitaire
+    //
+    // This is done after the cross-contract call to get the proper account sizes
+    // and avoid breaking wormhole call.
+    //
+    // It can be removed once wormhole mitigates this problem and upgrades its contract
+
+    // Checking the message account balance
+    let wh_message_balance = accs.wh_message.info().lamports();
+    let wh_message_rent_exempt = Rent::get()?.minimum_balance(accs.wh_message.info().data_len());
+
+    if wh_message_balance < wh_message_rent_exempt {
+        let required_deposit = wh_message_rent_exempt - wh_message_balance;
+
+        let transfer_ix = system_instruction::transfer(
+            accs.payer.key,
+            accs.wh_message.info().key,
+            required_deposit,
+        );
+        invoke(&transfer_ix, ctx.accounts)?
+    }
+
+    // Checking the sequence account balance
+    let wh_sequence_balance = accs.wh_sequence.info().lamports();
+    let wh_sequence_rent_exempt = Rent::get()?.minimum_balance(accs.wh_sequence.data_len());
+
+    if wh_sequence_balance < wh_sequence_rent_exempt {
+        let required_deposit = wh_sequence_rent_exempt - wh_sequence_balance;
+
+        let transfer_ix =
+            system_instruction::transfer(accs.payer.key, accs.wh_sequence.key, required_deposit);
+        invoke(&transfer_ix, ctx.accounts)?
+    }
+
     Ok(())
 }