Add LoaderInstruction::InvokeMain (#5116)

* Remove unreachable, untested runtime check

* tx_data -> ix_data

* Add LoaderInstruction::InvokeMain

* Add test and allow loaders to be registered statically.

* Fix clippy error

programs/bpf_loader_api/src/lib.rs

@@ -85,11 +85,46 @@ fn deserialize_parameters(keyed_accounts: &mut [KeyedAccount], buffer: &[u8]) {
 pub fn process_instruction(
     program_id: &Pubkey,
     keyed_accounts: &mut [KeyedAccount],
-    tx_data: &[u8],
+    ix_data: &[u8],
 ) -> Result<(), InstructionError> {
     solana_logger::setup();
 
-    if keyed_accounts[0].account.executable {
+    if let Ok(instruction) = bincode::deserialize(ix_data) {
+        match instruction {
+            LoaderInstruction::Write { offset, bytes } => {
+                if keyed_accounts[0].signer_key().is_none() {
+                    warn!("key[0] did not sign the transaction");
+                    return Err(InstructionError::GenericError);
+                }
+                let offset = offset as usize;
+                let len = bytes.len();
+                debug!("Write: offset={} length={}", offset, len);
+                if keyed_accounts[0].account.data.len() < offset + len {
+                    warn!(
+                        "Write overflow: {} < {}",
+                        keyed_accounts[0].account.data.len(),
+                        offset + len
+                    );
+                    return Err(InstructionError::GenericError);
+                }
+                keyed_accounts[0].account.data[offset..offset + len].copy_from_slice(&bytes);
+            }
+            LoaderInstruction::Finalize => {
+                if keyed_accounts[0].signer_key().is_none() {
+                    warn!("key[0] did not sign the transaction");
+                    return Err(InstructionError::GenericError);
+                }
+                keyed_accounts[0].account.executable = true;
+                info!(
+                    "Finalize: account {:?}",
+                    keyed_accounts[0].signer_key().unwrap()
+                );
+            }
+            LoaderInstruction::InvokeMain { data } => {
+                if !keyed_accounts[0].account.executable {
+                    warn!("BPF account not executable");
+                    return Err(InstructionError::GenericError);
+                }
                 let (progs, params) = keyed_accounts.split_at_mut(1);
                 let prog = &progs[0].account.data;
                 info!("Call BPF program");
@@ -100,7 +135,7 @@ pub fn process_instruction(
                         return Err(InstructionError::GenericError);
                     }
                 };
-        let mut v = serialize_parameters(program_id, params, &tx_data);
+                let mut v = serialize_parameters(program_id, params, &data);
 
                 match vm.execute_program(v.as_mut_slice(), &[], &[heap_region]) {
                     Ok(status) => {
@@ -119,36 +154,10 @@ pub fn process_instruction(
                     "BPF program executed {} instructions",
                     vm.get_last_instruction_count()
                 );
-    } else if let Ok(instruction) = bincode::deserialize(tx_data) {
-        if keyed_accounts[0].signer_key().is_none() {
-            warn!("key[0] did not sign the transaction");
-            return Err(InstructionError::GenericError);
-        }
-        match instruction {
-            LoaderInstruction::Write { offset, bytes } => {
-                let offset = offset as usize;
-                let len = bytes.len();
-                debug!("Write: offset={} length={}", offset, len);
-                if keyed_accounts[0].account.data.len() < offset + len {
-                    warn!(
-                        "Write overflow: {} < {}",
-                        keyed_accounts[0].account.data.len(),
-                        offset + len
-                    );
-                    return Err(InstructionError::GenericError);
-                }
-                keyed_accounts[0].account.data[offset..offset + len].copy_from_slice(&bytes);
-            }
-            LoaderInstruction::Finalize => {
-                keyed_accounts[0].account.executable = true;
-                info!(
-                    "Finalize: account {:?}",
-                    keyed_accounts[0].signer_key().unwrap()
-                );
             }
         }
     } else {
-        warn!("Invalid program transaction: {:?}", tx_data);
+        warn!("Invalid instruction data: {:?}", ix_data);
         return Err(InstructionError::GenericError);
     }
     Ok(())

runtime/src/message_processor.rs

@@ -6,11 +6,13 @@ use solana_sdk::account::{
 };
 use solana_sdk::instruction::{CompiledInstruction, InstructionError};
 use solana_sdk::instruction_processor_utils;
+use solana_sdk::loader_instruction::LoaderInstruction;
 use solana_sdk::message::Message;
 use solana_sdk::pubkey::Pubkey;
 use solana_sdk::system_program;
 use solana_sdk::transaction::TransactionError;
 use std::collections::HashMap;
+use std::io::Write;
 use std::sync::RwLock;
 
 #[cfg(unix)]
@@ -92,6 +94,27 @@ fn verify_instruction(
     Ok(())
 }
 
+/// Return instruction data to pass to process_instruction().
+/// When a loader is detected, the instruction data is wrapped with a LoaderInstruction
+/// to signal to the loader that the instruction data should be used as arguments when
+/// invoking a "main()" function.
+fn get_loader_instruction_data<'a>(
+    loaders: &[(Pubkey, Account)],
+    ix_data: &'a [u8],
+    loader_ix_data: &'a mut Vec<u8>,
+) -> &'a [u8] {
+    if loaders.len() > 1 {
+        let ix = LoaderInstruction::InvokeMain {
+            data: ix_data.to_vec(),
+        };
+        let ix_data = bincode::serialize(&ix).unwrap();
+        loader_ix_data.write_all(&ix_data).unwrap();
+        loader_ix_data
+    } else {
+        ix_data
+    }
+}
+
 pub type ProcessInstruction =
     fn(&Pubkey, &mut [KeyedAccount], &[u8]) -> Result<(), InstructionError>;
 
@@ -141,6 +164,13 @@ impl MessageProcessor {
     ) -> Result<(), InstructionError> {
         let program_id = instruction.program_id(&message.account_keys);
 
+        let mut loader_ix_data = vec![];
+        let ix_data = get_loader_instruction_data(
+            executable_accounts,
+            &instruction.data,
+            &mut loader_ix_data,
+        );
+
         let mut keyed_accounts = create_keyed_credit_only_accounts(executable_accounts);
         let mut keyed_accounts2: Vec<_> = instruction
             .accounts
@@ -168,18 +198,19 @@ impl MessageProcessor {
 
         for (id, process_instruction) in &self.instruction_processors {
             if id == program_id {
-                return process_instruction(
-                    &program_id,
-                    &mut keyed_accounts[1..],
-                    &instruction.data,
-                );
+                return process_instruction(&program_id, &mut keyed_accounts[1..], &ix_data);
             }
         }
 
-        native_loader::entrypoint(
+        assert!(
+            keyed_accounts[0].account.executable,
+            "loader not executable"
+        );
+
+        native_loader::invoke_entrypoint(
             &program_id,
             &mut keyed_accounts,
-            &instruction.data,
+            ix_data,
             &self.symbol_cache,
         )
     }
@@ -523,4 +554,37 @@ mod tests {
             ))
         );
     }
+
+    #[test]
+    fn test_get_loader_instruction_data() {
+        // First ensure the ix_data is unaffected if not invoking via a loader.
+        let ix_data = [1];
+        let mut loader_ix_data = vec![];
+
+        let native_pubkey = Pubkey::new_rand();
+        let native_loader = (native_pubkey, Account::new(0, 0, &native_pubkey));
+        assert_eq!(
+            get_loader_instruction_data(&[native_loader.clone()], &ix_data, &mut loader_ix_data),
+            &ix_data
+        );
+
+        // Now ensure the ix_data is wrapped when there's a loader present.
+        let acme_pubkey = Pubkey::new_rand();
+        let acme_loader = (acme_pubkey, Account::new(0, 0, &native_pubkey));
+        let expected_ix = LoaderInstruction::InvokeMain {
+            data: ix_data.to_vec(),
+        };
+        let expected_ix_data = bincode::serialize(&expected_ix).unwrap();
+        assert_eq!(
+            get_loader_instruction_data(
+                &[native_loader.clone(), acme_loader.clone()],
+                &ix_data,
+                &mut loader_ix_data
+            ),
+            &expected_ix_data[..]
+        );
+
+        // Note there was an allocation in the input vector.
+        assert_eq!(loader_ix_data, expected_ix_data);
+    }
 }

runtime/src/native_loader.rs

@@ -64,13 +64,12 @@ fn library_open(path: &PathBuf) -> std::io::Result<Library> {
     Library::open(Some(path), libc::RTLD_NODELETE | libc::RTLD_NOW)
 }
 
-pub fn entrypoint(
+pub fn invoke_entrypoint(
     program_id: &Pubkey,
     keyed_accounts: &mut [KeyedAccount],
     ix_data: &[u8],
     symbol_cache: &SymbolCache,
 ) -> Result<(), InstructionError> {
-    if keyed_accounts[0].account.executable {
     // dispatch it
     let (names, params) = keyed_accounts.split_at_mut(1);
     let name_vec = &names[0].account.data;
@@ -114,8 +113,4 @@ pub fn entrypoint(
             Err(InstructionError::GenericError)
         }
     }
-    } else {
-        warn!("Invalid data in instruction: {:?}", ix_data);
-        Err(InstructionError::GenericError)
-    }
 }

sdk/src/loader_instruction.rs

@@ -18,6 +18,11 @@ pub enum LoaderInstruction {
     ///
     /// The transaction must be signed by key[0]
     Finalize,
+
+    /// Invoke the "main" entrypoint with the given data.
+    ///
+    /// * key[0] - an executable account
+    InvokeMain { data: Vec<u8> },
 }
 
 pub fn write(