Restore ALL behavior; add enum variant, comments, and help text to make behavior clearer (#21854)

cli/src/spend_utils.rs

@@ -16,6 +16,7 @@ use {
 pub enum SpendAmount {
     All,
     Some(u64),
+    RentExempt,
 }
 
 impl Default for SpendAmount {
@@ -89,6 +90,7 @@ where
             0,
             from_pubkey,
             fee_pubkey,
+            0,
             build_message,
         );
         Ok((message, spend))
@@ -96,12 +98,19 @@ where
         let from_balance = rpc_client
             .get_balance_with_commitment(from_pubkey, commitment)?
             .value;
+        let from_rent_exempt_minimum = if amount == SpendAmount::RentExempt {
+            let data = rpc_client.get_account_data(from_pubkey)?;
+            rpc_client.get_minimum_balance_for_rent_exemption(data.len())?
+        } else {
+            0
+        };
         let (message, SpendAndFee { spend, fee }) = resolve_spend_message(
             amount,
             fee_calculator,
             from_balance,
             from_pubkey,
             fee_pubkey,
+            from_rent_exempt_minimum,
             build_message,
         );
         if from_pubkey == fee_pubkey {
@@ -137,6 +146,7 @@ fn resolve_spend_message<F>(
     from_balance: u64,
     from_pubkey: &Pubkey,
     fee_pubkey: &Pubkey,
+    from_rent_exempt_minimum: u64,
     build_message: F,
 ) -> (Message, SpendAndFee)
 where
@@ -170,5 +180,22 @@ where
                 },
             )
         }
+        SpendAmount::RentExempt => {
+            let dummy_message = build_message(0);
+            let fee = calculate_fee(fee_calculator, &[&dummy_message]);
+            let mut lamports = if from_pubkey == fee_pubkey {
+                from_balance.saturating_sub(fee)
+            } else {
+                from_balance
+            };
+            lamports = lamports.saturating_sub(from_rent_exempt_minimum);
+            (
+                build_message(lamports),
+                SpendAndFee {
+                    spend: lamports,
+                    fee,
+                },
+            )
+        }
     }
 }

cli/src/vote.rs

@@ -356,7 +356,7 @@ impl VoteSubCommands for App<'_, '_> {
                         .takes_value(true)
                         .required(true)
                         .validator(is_amount_or_all)
-                        .help("The amount to withdraw, in SOL; accepts keyword ALL"),
+                        .help("The amount to withdraw, in SOL; accepts keyword ALL, which for this command means account balance minus rent-exempt minimum"),
                 )
                 .arg(
                     Arg::with_name("authorized_withdrawer")
@@ -621,7 +621,13 @@ pub fn parse_withdraw_from_vote_account(
         pubkey_of_signer(matches, "vote_account_pubkey", wallet_manager)?.unwrap();
     let destination_account_pubkey =
         pubkey_of_signer(matches, "destination_account_pubkey", wallet_manager)?.unwrap();
-    let withdraw_amount = SpendAmount::new_from_matches(matches, "amount");
+    let mut withdraw_amount = SpendAmount::new_from_matches(matches, "amount");
+    // As a safeguard for vote accounts for running validators, `ALL` withdraws only the amount in
+    // excess of the rent-exempt minimum. In order to close the account with this subcommand, a
+    // validator must specify the withdrawal amount precisely.
+    if withdraw_amount == SpendAmount::All {
+        withdraw_amount = SpendAmount::RentExempt;
+    }
 
     let (withdraw_authority, withdraw_authority_pubkey) =
         signer_of(matches, "authorized_withdrawer", wallet_manager)?;
@@ -1877,7 +1883,7 @@ mod tests {
                     vote_account_pubkey: read_keypair_file(&keypair_file).unwrap().pubkey(),
                     destination_account_pubkey: pubkey,
                     withdraw_authority: 0,
-                    withdraw_amount: SpendAmount::All,
+                    withdraw_amount: SpendAmount::RentExempt,
                     sign_only: false,
                     dump_transaction_message: false,
                     blockhash_query: BlockhashQuery::All(blockhash_query::Source::Cluster),