stake-pool: Enforce that pool mint uses 9 decimal places (HAL-03)

stake-pool/program/src/error.rs

@@ -144,6 +144,11 @@ pub enum StakePoolError {
     /// Instruction exceeds desired slippage limit
     #[error("Instruction exceeds desired slippage limit")]
     ExceededSlippage,
+
+    // 40.
+    /// Provided mint does not have 9 decimals to match SOL
+    #[error("IncorrectMintDecimals")]
+    IncorrectMintDecimals,
 }
 impl From<StakePoolError> for ProgramError {
     fn from(e: StakePoolError) -> Self {

stake-pool/program/src/processor.rs

@@ -39,6 +39,7 @@ use {
     spl_token_2022::{
         check_spl_token_program_account,
         extension::{BaseStateWithExtensions, StateWithExtensions},
+        native_mint,
         state::Mint,
     },
     std::num::NonZeroU32,
@@ -828,6 +829,10 @@ impl Processor {
                 return Err(StakePoolError::NonZeroPoolTokenSupply.into());
             }
 
+            if pool_mint.base.decimals != native_mint::DECIMALS {
+                return Err(StakePoolError::IncorrectMintDecimals.into());
+            }
+
             if !pool_mint
                 .base
                 .mint_authority
@@ -3995,6 +4000,7 @@ impl PrintProgramError for StakePoolError {
             StakePoolError::UnsupportedMintExtension => msg!("Error: mint has an unsupported extension"),
             StakePoolError::UnsupportedFeeAccountExtension => msg!("Error: fee account has an unsupported extension"),
             StakePoolError::ExceededSlippage => msg!("Error: instruction exceeds desired slippage limit"),
+            StakePoolError::IncorrectMintDecimals => msg!("Error: Provided mint does not have 9 decimals to match SOL"),
         }
     }
 }

stake-pool/program/tests/helpers/mod.rs

@@ -36,6 +36,7 @@ use {
     },
     spl_token_2022::{
         extension::{ExtensionType, StateWithExtensionsOwned},
+        native_mint,
         state::{Account, Mint},
     },
     std::{convert::TryInto, num::NonZeroU32},
@@ -2013,7 +2014,7 @@ impl Default for StakePoolAccounts {
             token_program_id: spl_token::id(),
             pool_mint,
             pool_fee_account,
-            pool_decimals: 0,
+            pool_decimals: native_mint::DECIMALS,
             manager,
             staker,
             withdraw_authority,

stake-pool/program/tests/initialize.rs

@@ -448,7 +448,7 @@ async fn fail_with_freeze_authority() {
                 &wrong_mint.pubkey(),
                 &stake_pool_accounts.withdraw_authority,
                 Some(&stake_pool_accounts.withdraw_authority),
-                0,
+                stake_pool_accounts.pool_decimals,
             )
             .unwrap(),
         ],
@@ -1603,3 +1603,30 @@ async fn success_with_extra_reserve_lamports() {
     .await;
     assert_eq!(init_pool_tokens, init_lamports);
 }
+
+#[tokio::test]
+async fn fail_with_incorrect_mint_decimals() {
+    let (mut banks_client, payer, recent_blockhash) = program_test().start().await;
+    let stake_pool_accounts = StakePoolAccounts {
+        pool_decimals: 8,
+        ..Default::default()
+    };
+    let error = stake_pool_accounts
+        .initialize_stake_pool(
+            &mut banks_client,
+            &payer,
+            &recent_blockhash,
+            MINIMUM_RESERVE_LAMPORTS,
+        )
+        .await
+        .unwrap_err()
+        .unwrap();
+
+    assert_eq!(
+        error,
+        TransactionError::InstructionError(
+            2,
+            InstructionError::Custom(error::StakePoolError::IncorrectMintDecimals as u32),
+        )
+    );
+}