Cli stake-split: adjust transfer amount if recipient has lamports (an…

…za-xyz#266)

* Remove incorrect check

* Move to closure

* Use match statement instead

* Adjust rent_exempt_reserve by existing balance

* Only transfer lamports if rent_exempt_reserve needs are greater than 0

* Rename variable for clarity

* Add minimum-delegation check

* Bump test split amount to meet arbitrary mock minimum-delegation amount

cli/src/cli.rs

@@ -2254,7 +2254,7 @@ mod tests {
             memo: None,
             split_stake_account: 1,
             seed: None,
-            lamports: 30,
+            lamports: 200_000_000,
             fee_payer: 0,
             compute_unit_price: None,
             rent_exempt_reserve: None,

cli/src/stake.rs

@@ -38,13 +38,14 @@ use {
     },
     solana_rpc_client_nonce_utils::blockhash_query::BlockhashQuery,
     solana_sdk::{
-        account::from_account,
+        account::{from_account, Account},
         account_utils::StateMut,
         clock::{Clock, UnixTimestamp, SECONDS_PER_DAY},
         commitment_config::CommitmentConfig,
         epoch_schedule::EpochSchedule,
         feature_set,
         message::Message,
+        native_token::Sol,
         pubkey::Pubkey,
         stake::{
             self,
@@ -1980,40 +1981,49 @@ pub fn process_split_stake(
     };
 
     let rent_exempt_reserve = if !sign_only {
-        if let Ok(stake_account) = rpc_client.get_account(&split_stake_account_address) {
-            if stake_account.owner == stake::program::id() {
-                return Err(CliError::BadParameter(format!(
+        let stake_minimum_delegation = rpc_client.get_stake_minimum_delegation()?;
+        if lamports < stake_minimum_delegation {
+            let lamports = Sol(lamports);
+            let stake_minimum_delegation = Sol(stake_minimum_delegation);
+            return Err(CliError::BadParameter(format!(
+                "need at least {stake_minimum_delegation} for minimum stake delegation, \
+                 provided: {lamports}"
+            ))
+            .into());
+        }
+
+        let check_stake_account = |account: Account| -> Result<u64, CliError> {
+            match account.owner {
+                owner if owner == stake::program::id() => Err(CliError::BadParameter(format!(
                     "Stake account {split_stake_account_address} already exists"
-                ))
-                .into());
-            } else if stake_account.owner == system_program::id() {
-                if !stake_account.data.is_empty() {
-                    return Err(CliError::BadParameter(format!(
-                        "Account {split_stake_account_address} has data and cannot be used to split stake"
-                    ))
-                    .into());
+                ))),
+                owner if owner == system_program::id() => {
+                    if !account.data.is_empty() {
+                        Err(CliError::BadParameter(format!(
+                            "Account {split_stake_account_address} has data and cannot be used to split stake"
+                        )))
+                    } else {
+                        // if `stake_account`'s owner is the system_program and its data is
+                        // empty, `stake_account` is allowed to receive the stake split
+                        Ok(account.lamports)
+                    }
                 }
-            // if `stake_account`'s owner is the system_program and its data is
-            // empty, `stake_account` is allowed to receive the stake split
-            } else {
-                return Err(CliError::BadParameter(format!(
+                _ => Err(CliError::BadParameter(format!(
                     "Account {split_stake_account_address} already exists and cannot be used to split stake"
-                ))
-                .into());
+                )))
             }
-        }
+        };
+        let current_balance =
+            if let Ok(stake_account) = rpc_client.get_account(&split_stake_account_address) {
+                check_stake_account(stake_account)?
+            } else {
+                0
+            };
 
-        let minimum_balance =
+        let rent_exempt_reserve =
             rpc_client.get_minimum_balance_for_rent_exemption(StakeStateV2::size_of())?;
 
-        if lamports < minimum_balance {
-            return Err(CliError::BadParameter(format!(
-                "need at least {minimum_balance} lamports for stake account to be rent exempt, \
-                 provided lamports: {lamports}"
-            ))
-            .into());
-        }
-        minimum_balance
+        rent_exempt_reserve.saturating_sub(current_balance)
     } else {
         rent_exempt_reserve
             .cloned()
@@ -2022,11 +2032,14 @@ pub fn process_split_stake(
 
     let recent_blockhash = blockhash_query.get_blockhash(rpc_client, config.commitment)?;
 
-    let mut ixs = vec![system_instruction::transfer(
-        &fee_payer.pubkey(),
-        &split_stake_account_address,
-        rent_exempt_reserve,
-    )];
+    let mut ixs = vec![];
+    if rent_exempt_reserve > 0 {
+        ixs.push(system_instruction::transfer(
+            &fee_payer.pubkey(),
+            &split_stake_account_address,
+            rent_exempt_reserve,
+        ));
+    }
     if let Some(seed) = split_stake_account_seed {
         ixs.append(
             &mut stake_instruction::split_with_seed(