Add support for SDK sysvar types (#5876)

programs/bpf/rust/sysval/src/lib.rs

@@ -0,0 +1,43 @@
+//! @brief Example Rust-based BPF program that tests sysval use
+
+extern crate solana_sdk;
+use solana_sdk::{
+    account_info::AccountInfo,
+    clock::{get_segment_from_slot, DEFAULT_SLOTS_PER_EPOCH, DEFAULT_SLOTS_PER_SEGMENT},
+    entrypoint,
+    entrypoint::SUCCESS,
+    pubkey::Pubkey,
+    sysvar::{
+        clock::Clock, fees::Fees, rewards::Rewards, slot_hashes::SlotHashes,
+        stake_history::StakeHistory,
+    },
+};
+
+entrypoint!(process_instruction);
+fn process_instruction(_program_id: &Pubkey, accounts: &mut [AccountInfo], _data: &[u8]) -> u32 {
+    // Clock
+    let clock = Clock::from_account_info(&accounts[2]).unwrap();
+    assert_eq!(clock.slot, DEFAULT_SLOTS_PER_EPOCH + 1);
+    assert_eq!(
+        clock.segment,
+        get_segment_from_slot(clock.slot, DEFAULT_SLOTS_PER_SEGMENT)
+    );
+
+    // Fees
+    let fees = Fees::from_account_info(&accounts[3]).unwrap();
+    let burn = fees.fee_calculator.burn(42);
+    assert_eq!(burn, (21, 21));
+
+    // Rewards
+    let _ = Rewards::from_account_info(&accounts[4]).unwrap();
+
+    // Slot Hashes
+    let slot_hashes = SlotHashes::from_account_info(&accounts[5]).unwrap();
+    assert_eq!(slot_hashes.len(), 1);
+
+    // Stake History
+    let stake_history = StakeHistory::from_account_info(&accounts[6]).unwrap();
+    assert_eq!(stake_history.len(), 1);
+
+    SUCCESS
+}