rust: Implement ExecutionContext (host interface)

bindings/rust/evmc-vm/src/lib.rs

@@ -6,7 +6,6 @@
 pub extern crate evmc_sys;
 pub use evmc_sys as ffi;
 
-// TODO: Add helpers for host interface
 // TODO: Add convenient helpers for evmc_execute
 // TODO: Add a derive macro here for creating evmc_create
 
@@ -18,6 +17,14 @@ pub struct ExecutionResult {
     create_address: ffi::evmc_address,
 }
 
+/// EVMC context structure. Exposes the EVMC host functions, message data, and transaction context
+/// to the executing VM.
+pub struct ExecutionContext<'a> {
+    message: &'a ffi::evmc_message,
+    context: &'a mut ffi::evmc_context,
+    tx_context: ffi::evmc_tx_context,
+}
+
 impl ExecutionResult {
     pub fn new(
         _status_code: ffi::evmc_status_code,
@@ -61,6 +68,172 @@ impl ExecutionResult {
     }
 }
 
+impl<'a> ExecutionContext<'a> {
+    pub fn new(_message: &'a ffi::evmc_message, _context: &'a mut ffi::evmc_context) -> Self {
+        let _tx_context = unsafe {
+            assert!((*(_context.host)).get_tx_context.is_some());
+            (*(_context.host)).get_tx_context.unwrap()(_context as *mut ffi::evmc_context)
+        };
+
+        ExecutionContext {
+            message: _message,
+            context: _context,
+            tx_context: _tx_context,
+        }
+    }
+
+    pub fn get_message(&self) -> &ffi::evmc_message {
+        &self.message
+    }
+
+    pub fn get_tx_context(&mut self) -> &ffi::evmc_tx_context {
+        &self.tx_context
+    }
+
+    pub fn account_exists(&mut self, address: &ffi::evmc_address) -> bool {
+        unsafe {
+            assert!((*self.context.host).account_exists.is_some());
+            (*self.context.host).account_exists.unwrap()(
+                self.context as *mut ffi::evmc_context,
+                address as *const ffi::evmc_address,
+            )
+        }
+    }
+
+    pub fn get_storage(
+        &mut self,
+        address: &ffi::evmc_address,
+        key: &ffi::evmc_bytes32,
+    ) -> ffi::evmc_bytes32 {
+        unsafe {
+            assert!((*self.context.host).get_storage.is_some());
+            (*self.context.host).get_storage.unwrap()(
+                self.context as *mut ffi::evmc_context,
+                address as *const ffi::evmc_address,
+                key as *const ffi::evmc_bytes32,
+            )
+        }
+    }
+
+    pub fn set_storage(
+        &mut self,
+        address: &ffi::evmc_address,
+        key: &ffi::evmc_bytes32,
+        value: &ffi::evmc_bytes32,
+    ) -> ffi::evmc_storage_status {
+        unsafe {
+            assert!((*self.context.host).set_storage.is_some());
+            (*self.context.host).set_storage.unwrap()(
+                self.context as *mut ffi::evmc_context,
+                address as *const ffi::evmc_address,
+                key as *const ffi::evmc_bytes32,
+                value as *const ffi::evmc_bytes32,
+            )
+        }
+    }
+
+    pub fn get_balance(&mut self, address: &ffi::evmc_address) -> ffi::evmc_bytes32 {
+        unsafe {
+            assert!((*self.context.host).get_balance.is_some());
+            (*self.context.host).get_balance.unwrap()(
+                self.context as *mut ffi::evmc_context,
+                address as *const ffi::evmc_address,
+            )
+        }
+    }
+
+    pub fn get_code_size(&mut self, address: &ffi::evmc_address) -> usize {
+        unsafe {
+            assert!((*self.context.host).get_code_size.is_some());
+            (*self.context.host).get_code_size.unwrap()(
+                self.context as *mut ffi::evmc_context,
+                address as *const ffi::evmc_address,
+            )
+        }
+    }
+
+    pub fn get_code_hash(&mut self, address: &ffi::evmc_address) -> ffi::evmc_bytes32 {
+        unsafe {
+            assert!((*self.context.host).get_code_size.is_some());
+            (*self.context.host).get_code_hash.unwrap()(
+                self.context as *mut ffi::evmc_context,
+                address as *const ffi::evmc_address,
+            )
+        }
+    }
+
+    pub fn copy_code(
+        &mut self,
+        address: &ffi::evmc_address,
+        code_offset: usize,
+        buffer: &mut [u8],
+    ) -> usize {
+        unsafe {
+            assert!((*self.context.host).copy_code.is_some());
+            (*self.context.host).copy_code.unwrap()(
+                self.context as *mut ffi::evmc_context,
+                address as *const ffi::evmc_address,
+                code_offset,
+                // FIXME: ensure that alignment of the array elements is OK
+                buffer.as_mut_ptr(),
+                buffer.len(),
+            )
+        }
+    }
+
+    pub fn selfdestruct(&mut self, address: &ffi::evmc_address, beneficiary: &ffi::evmc_address) {
+        unsafe {
+            assert!((*self.context.host).selfdestruct.is_some());
+            (*self.context.host).selfdestruct.unwrap()(
+                self.context as *mut ffi::evmc_context,
+                address as *const ffi::evmc_address,
+                beneficiary as *const ffi::evmc_address,
+            )
+        }
+    }
+
+    pub fn call(&mut self, message: &ffi::evmc_message) -> ExecutionResult {
+        unsafe {
+            assert!((*self.context.host).call.is_some());
+            (*self.context.host).call.unwrap()(
+                self.context as *mut ffi::evmc_context,
+                message as *const ffi::evmc_message,
+            )
+            .into()
+        }
+    }
+
+    pub fn get_block_hash(&mut self, num: i64) -> ffi::evmc_bytes32 {
+        unsafe {
+            assert!((*self.context.host).get_block_hash.is_some());
+            (*self.context.host).get_block_hash.unwrap()(
+                self.context as *mut ffi::evmc_context,
+                num,
+            )
+        }
+    }
+
+    pub fn emit_log(
+        &mut self,
+        address: &ffi::evmc_address,
+        data: &[u8],
+        topics: &[ffi::evmc_bytes32],
+    ) {
+        unsafe {
+            assert!((*self.context.host).emit_log.is_some());
+            (*self.context.host).emit_log.unwrap()(
+                self.context as *mut ffi::evmc_context,
+                address as *const ffi::evmc_address,
+                // FIXME: ensure that alignment of the array elements is OK
+                data.as_ptr(),
+                data.len(),
+                topics.as_ptr(),
+                topics.len(),
+            )
+        }
+    }
+}
+
 impl From<ffi::evmc_result> for ExecutionResult {
     fn from(result: ffi::evmc_result) -> Self {
         let ret = ExecutionResult {
@@ -308,4 +481,99 @@ mod tests {
             }
         }
     }
+
+    unsafe extern "C" fn get_dummy_tx_context(
+        _context: *mut ffi::evmc_context,
+    ) -> ffi::evmc_tx_context {
+        ffi::evmc_tx_context {
+            tx_gas_price: ffi::evmc_uint256be { bytes: [0u8; 32] },
+            tx_origin: ffi::evmc_address { bytes: [0u8; 20] },
+            block_coinbase: ffi::evmc_address { bytes: [0u8; 20] },
+            block_number: 42,
+            block_timestamp: 235117,
+            block_gas_limit: 105023,
+            block_difficulty: ffi::evmc_uint256be { bytes: [0xaa; 32] },
+        }
+    }
+
+    unsafe extern "C" fn get_dummy_code_size(
+        _context: *mut ffi::evmc_context,
+        _addr: *const ffi::evmc_address,
+    ) -> usize {
+        105023 as usize
+    }
+
+    // Update these when needed for tests
+    fn get_dummy_context() -> ffi::evmc_context {
+        ffi::evmc_context {
+            host: Box::into_raw(Box::new(ffi::evmc_host_interface {
+                account_exists: None,
+                get_storage: None,
+                set_storage: None,
+                get_balance: None,
+                get_code_size: Some(get_dummy_code_size),
+                get_code_hash: None,
+                copy_code: None,
+                selfdestruct: None,
+                call: None,
+                get_tx_context: Some(get_dummy_tx_context),
+                get_block_hash: None,
+                emit_log: None,
+            })),
+        }
+    }
+
+    fn get_dummy_message() -> ffi::evmc_message {
+        ffi::evmc_message {
+            kind: ffi::evmc_call_kind::EVMC_CALL,
+            flags: 0,
+            depth: 123,
+            gas: 105023,
+            destination: ffi::evmc_address { bytes: [0u8; 20] },
+            sender: ffi::evmc_address { bytes: [0u8; 20] },
+            input_data: std::ptr::null() as *const u8,
+            input_size: 0,
+            value: ffi::evmc_uint256be { bytes: [0u8; 32] },
+            create2_salt: ffi::evmc_uint256be { bytes: [0u8; 32] },
+        }
+    }
+
+    #[test]
+    fn execution_context() {
+        let msg = get_dummy_message();
+        let mut context_raw = get_dummy_context();
+        let mut exe_context = ExecutionContext::new(&msg, &mut context_raw);
+
+        let a = exe_context.get_tx_context();
+        let b = unsafe { get_dummy_tx_context(&mut get_dummy_context() as *mut ffi::evmc_context) };
+
+        assert_eq!(a.block_gas_limit, b.block_gas_limit);
+        assert_eq!(a.block_timestamp, b.block_timestamp);
+        assert_eq!(a.block_number, b.block_number);
+
+        let c = exe_context.get_message();
+        let d = get_dummy_message();
+
+        assert_eq!(c.kind, d.kind);
+        assert_eq!(c.flags, d.flags);
+        assert_eq!(c.depth, d.depth);
+        assert_eq!(c.gas, d.gas);
+        assert_eq!(c.input_data, d.input_data);
+        assert_eq!(c.input_size, d.input_size);
+    }
+
+    #[test]
+    fn get_code_size() {
+        let msg = get_dummy_message();
+
+        // This address is useless. Just a dummy parameter for the interface function.
+        let test_addr = ffi::evmc_address { bytes: [0u8; 20] };
+        let mut context_raw = get_dummy_context();
+        let mut exe_context = ExecutionContext::new(&msg, &mut context_raw);
+
+        let a: usize = 105023;
+        let b = exe_context.get_code_size(&test_addr);
+
+        assert_eq!(a, b);
+    }
 }

examples/example-rust-vm/src/lib.rs

@@ -1,6 +1,6 @@
 extern crate evmc_vm;
 
-use evmc_vm::evmc_sys as ffi;
+use evmc_vm::*;
 
 extern "C" fn execute(
     instance: *mut ffi::evmc_instance,
@@ -10,7 +10,13 @@ extern "C" fn execute(
     code: *const u8,
     code_size: usize,
 ) -> ffi::evmc_result {
-    let is_create = unsafe { (*msg).kind == ffi::evmc_call_kind::EVMC_CREATE };
+    let execution_ctx = unsafe {
+        ExecutionContext::new(
+            msg.as_ref().expect("tester passed nullptr as message"),
+            context.as_mut().expect("tester passed nullptr as context"),
+        )
+    };
+    let is_create = execution_ctx.get_message().kind == ffi::evmc_call_kind::EVMC_CREATE;
 
     if is_create {
         evmc_vm::ExecutionResult::new(ffi::evmc_status_code::EVMC_FAILURE, 0, None, None).into()