Add native loader entry points (#9486)

sdk/src/entrypoint_native.rs

@@ -7,7 +7,19 @@ use crate::{account::KeyedAccount, instruction::InstructionError, pubkey::Pubkey
 /// program_id: Program ID of the currently executing program
 /// keyed_accounts: Accounts passed as part of the instruction
 /// instruction_data: Instruction data
-pub type Entrypoint = unsafe extern "C" fn(
+pub type ProgramEntrypoint = unsafe extern "C" fn(
+    program_id: &Pubkey,
+    keyed_accounts: &[KeyedAccount],
+    instruction_data: &[u8],
+) -> Result<(), InstructionError>;
+
+// Prototype of a native loader entry point
+///
+/// program_id: Program ID of the currently executing program
+/// keyed_accounts: Accounts passed as part of the instruction
+/// instruction_data: Instruction data
+/// invoke_context: Invocation context
+pub type LoaderEntrypoint = unsafe extern "C" fn(
     program_id: &Pubkey,
     keyed_accounts: &[KeyedAccount],
     instruction_data: &[u8],
@@ -103,3 +115,27 @@ macro_rules! declare_program(
         }
     )
 );
+
+/// Same as declare_program but for native loaders
+#[macro_export]
+macro_rules! declare_loader(
+    ($bs58_string:expr, $name:ident, $entrypoint:expr) => (
+        $crate::declare_id!($bs58_string);
+
+        #[macro_export]
+        macro_rules! $name {
+            () => {
+                (stringify!($name).to_string(), $crate::id())
+            };
+        }
+
+        #[no_mangle]
+        pub extern "C" fn $name(
+            program_id: &$crate::pubkey::Pubkey,
+            keyed_accounts: &[$crate::account::KeyedAccount],
+            instruction_data: &[u8],
+        ) -> Result<(), $crate::instruction::InstructionError> {
+            $entrypoint(program_id, keyed_accounts, instruction_data)
+        }
+    )
+);

sdk/src/instruction.rs

@@ -134,6 +134,10 @@ pub enum InstructionError {
     /// Executable accounts must be rent exempt
     #[error("executable accounts must be rent exempt")]
     ExecutableAccountNotRentExempt,
+
+    /// Unsupported program id
+    #[error("Unsupported program id")]
+    UnsupportedProgramId,
 }
 
 impl InstructionError {