Add get_sysvar() helper to sdk

sdk/src/process_instruction.rs

@@ -4,6 +4,7 @@ use solana_sdk::{
     keyed_account::{create_keyed_accounts_unified, KeyedAccount},
     message::Message,
     pubkey::Pubkey,
+    sysvar::Sysvar,
 };
 use std::{cell::RefCell, fmt::Debug, rc::Rc, sync::Arc};
 
@@ -100,7 +101,7 @@ pub trait InvokeContext {
         deserialize_us: u64,
     );
     /// Get sysvar data
-    fn get_sysvar_data(&mut self, id: &Pubkey) -> Option<Rc<Vec<u8>>>;
+    fn get_sysvar_data(&self, id: &Pubkey) -> Option<Rc<Vec<u8>>>;
 }
 
 /// Convenience macro to log a message with an `Rc<RefCell<dyn Logger>>`
@@ -133,6 +134,21 @@ macro_rules! ic_msg {
     };
 }
 
+pub fn get_sysvar<T: Sysvar>(
+    invoke_context: &dyn InvokeContext,
+    id: &Pubkey,
+) -> Result<T, InstructionError> {
+    let sysvar_data = invoke_context.get_sysvar_data(id).ok_or_else(|| {
+        ic_msg!(invoke_context, "Unable to get sysvar {}", id);
+        InstructionError::UnsupportedSysvar
+    })?;
+
+    bincode::deserialize(&sysvar_data).map_err(|err| {
+        ic_msg!(invoke_context, "Unable to get sysvar {}: {:?}", id, err);
+        InstructionError::UnsupportedSysvar
+    })
+}
+
 #[derive(Clone, Copy, Debug, AbiExample)]
 pub struct BpfComputeBudget {
     /// Number of compute units that an instruction is allowed.  Compute units
@@ -338,6 +354,22 @@ impl<'a> MockInvokeContext<'a> {
         invoke_context
     }
 }
+
+pub fn mock_set_sysvar<T: Sysvar>(
+    mock_invoke_context: &mut MockInvokeContext,
+    id: Pubkey,
+    sysvar: T,
+) -> Result<(), InstructionError> {
+    let mut data = Vec::with_capacity(T::size_of());
+
+    bincode::serialize_into(&mut data, &sysvar).map_err(|err| {
+        ic_msg!(mock_invoke_context, "Unable to serialize sysvar: {:?}", err);
+        InstructionError::GenericError
+    })?;
+    mock_invoke_context.sysvars.push((id, Some(Rc::new(data))));
+    Ok(())
+}
+
 impl<'a> InvokeContext for MockInvokeContext<'a> {
     fn push(
         &mut self,
@@ -425,7 +457,7 @@ impl<'a> InvokeContext for MockInvokeContext<'a> {
         _deserialize_us: u64,
     ) {
     }
-    fn get_sysvar_data(&mut self, id: &Pubkey) -> Option<Rc<Vec<u8>>> {
+    fn get_sysvar_data(&self, id: &Pubkey) -> Option<Rc<Vec<u8>>> {
         self.sysvars
             .iter()
             .find_map(|(key, sysvar)| if id == key { sysvar.clone() } else { None })