Refactor vote state to remove double negative (backport #21244) (#21250)

* Refactor vote state to remove double negative (#21244)

(cherry picked from commit ef29d2d172)

# Conflicts:
#	runtime/src/stakes.rs

* resolve conflicts

Co-authored-by: Justin Starry <justin@solana.com>

programs/vote/src/vote_state/mod.rs

@@ -585,11 +585,11 @@ impl VoteState {
         Ok(())
     }
 
-    pub fn is_uninitialized_no_deser(data: &[u8]) -> bool {
+    pub fn is_correct_size_and_initialized(data: &[u8]) -> bool {
         const VERSION_OFFSET: usize = 4;
-        data.len() != VoteState::size_of()
+        data.len() == VoteState::size_of()
-            || data[VERSION_OFFSET..VERSION_OFFSET + DEFAULT_PRIOR_VOTERS_OFFSET]
+            && data[VERSION_OFFSET..VERSION_OFFSET + DEFAULT_PRIOR_VOTERS_OFFSET]
-                == [0; DEFAULT_PRIOR_VOTERS_OFFSET]
+                != [0; DEFAULT_PRIOR_VOTERS_OFFSET]
     }
 }
 
@@ -2082,25 +2082,31 @@ mod tests {
     }
 
     #[test]
-    fn test_is_uninitialized_no_deser() {
+    fn test_is_correct_size_and_initialized() {
         // Check all zeroes
         let mut vote_account_data = vec![0; VoteState::size_of()];
-        assert!(VoteState::is_uninitialized_no_deser(&vote_account_data));
+        assert!(!VoteState::is_correct_size_and_initialized(
+            &vote_account_data
+        ));
 
         // Check default VoteState
         let default_account_state = VoteStateVersions::new_current(VoteState::default());
         VoteState::serialize(&default_account_state, &mut vote_account_data).unwrap();
-        assert!(VoteState::is_uninitialized_no_deser(&vote_account_data));
+        assert!(!VoteState::is_correct_size_and_initialized(
+            &vote_account_data
+        ));
 
         // Check non-zero data shorter than offset index used
         let short_data = vec![1; DEFAULT_PRIOR_VOTERS_OFFSET];
-        assert!(VoteState::is_uninitialized_no_deser(&short_data));
+        assert!(!VoteState::is_correct_size_and_initialized(&short_data));
 
         // Check non-zero large account
         let mut large_vote_data = vec![1; 2 * VoteState::size_of()];
         let default_account_state = VoteStateVersions::new_current(VoteState::default());
         VoteState::serialize(&default_account_state, &mut large_vote_data).unwrap();
-        assert!(VoteState::is_uninitialized_no_deser(&vote_account_data));
+        assert!(!VoteState::is_correct_size_and_initialized(
+            &vote_account_data
+        ));
 
         // Check populated VoteState
         let account_state = VoteStateVersions::new_current(VoteState::new(
@@ -2113,6 +2119,8 @@ mod tests {
             &Clock::default(),
         ));
         VoteState::serialize(&account_state, &mut vote_account_data).unwrap();
-        assert!(!VoteState::is_uninitialized_no_deser(&vote_account_data));
+        assert!(VoteState::is_correct_size_and_initialized(
+            &vote_account_data
+        ));
     }
 }

runtime/src/stakes.rs

@@ -203,8 +203,10 @@ impl Stakes {
             let old = self.vote_accounts.remove(pubkey);
             // when account is removed (lamports == 0 or data uninitialized), don't read so that
             // given `pubkey` can be used for any owner in the future, while not affecting Stakes.
+            let vote_init_check_disabled = !check_vote_init;
             if account.lamports() != 0
-                && !(check_vote_init && VoteState::is_uninitialized_no_deser(account.data()))
+                && (vote_init_check_disabled
+                    || VoteState::is_correct_size_and_initialized(account.data()))
             {
                 let stake = old.as_ref().map_or_else(
                     || self.calculate_stake(pubkey, self.epoch, Some(&self.stake_history)),