v1.18: Support json parsing of epoch-rewards partition data sysvar ac…

…counts (backport of solana-labs#34914) (solana-labs#34926)

Support json parsing of epoch-rewards partition data sysvar accounts (solana-labs#34914)

(cherry picked from commit b9947bd)

Co-authored-by: Tyera <tyera@solana.com>

account-decoder/src/parse_sysvar.rs

@@ -9,6 +9,7 @@ use {
     bv::BitVec,
     solana_sdk::{
         clock::{Clock, Epoch, Slot, UnixTimestamp},
+        epoch_rewards_partition_data::EpochRewardsPartitionDataVersion,
         epoch_schedule::EpochSchedule,
         pubkey::Pubkey,
         rent::Rent,
@@ -96,7 +97,24 @@ pub fn parse_sysvar(data: &[u8], pubkey: &Pubkey) -> Result<SysvarAccountType, P
                 .ok()
                 .map(SysvarAccountType::EpochRewards)
         } else {
-            None
+            // EpochRewards PartitionData accounts are owned by the sysvar
+            // program, but have dynamically generated addresses. Test on
+            // whether account content deserializes properly.
+            if let Ok(epoch_rewards_partition_data) =
+                deserialize::<EpochRewardsPartitionDataVersion>(data)
+            {
+                let EpochRewardsPartitionDataVersion::V0(partition_data) =
+                    epoch_rewards_partition_data;
+                Some(SysvarAccountType::EpochRewardsPartitionData(
+                    UiEpochRewardsPartitionData {
+                        version: 0,
+                        num_partitions: partition_data.num_partitions as u64,
+                        parent_blockhash: partition_data.parent_blockhash.to_string(),
+                    },
+                ))
+            } else {
+                None
+            }
         }
     };
     parsed_account.ok_or(ParseAccountError::AccountNotParsable(
@@ -120,6 +138,7 @@ pub enum SysvarAccountType {
     StakeHistory(Vec<UiStakeHistoryEntry>),
     LastRestartSlot(UiLastRestartSlot),
     EpochRewards(EpochRewards),
+    EpochRewardsPartitionData(UiEpochRewardsPartitionData),
 }
 
 #[derive(Debug, Serialize, Deserialize, PartialEq, Eq, Default)]
@@ -239,6 +258,14 @@ pub struct UiLastRestartSlot {
     pub last_restart_slot: Slot,
 }
 
+#[derive(Debug, Serialize, Deserialize, PartialEq, Eq, Default)]
+#[serde(rename_all = "camelCase")]
+pub struct UiEpochRewardsPartitionData {
+    pub version: u32,
+    pub num_partitions: u64,
+    pub parent_blockhash: String,
+}
+
 #[cfg(test)]
 mod test {
     #[allow(deprecated)]