Fix constructor

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

@@ -1,6 +1,8 @@
 pub extern crate evmc_sys;
 pub use evmc_sys as ffi;
 
+use std::slice;
+
 // TODO: Add helpers for host interface
 // TODO: Add convenient helpers for evmc_result
 // TODO: Add convenient helpers for evmc_execute
@@ -12,25 +14,45 @@ pub use evmc_sys as ffi;
 pub struct EvmcResult(Box<ffi::evmc_result>);
 
 impl EvmcResult {
-    pub fn new(
-        status: ffi::evmc_status_code,
-        gasleft: i64,
-        output: &[u8],
-    ) -> Self {
+    pub fn new(status: ffi::evmc_status_code, gasleft: i64, output: Option<&[u8]>) -> Self {
         EvmcResult(Box::new(ffi::evmc_result {
             status_code: status,
             gas_left: gasleft,
-            output_data: output.as_ptr(),
-            output_size: output.len(),
+            output_data: if let Some(buf) = output {
+                buf.clone().as_ptr()
+            } else {
+                std::ptr::null()
+            },
+            output_size: if let Some(buf) = output { buf.len() } else { 0 },
             release: Some(release_result),
             create_address: ffi::evmc_address { bytes: [0u8; 20] },
             padding: [0u8; 4],
         }))
     }
+
+    pub fn gasleft(&self) -> i64 {
+        self.0.gas_left
+    }
+
+    pub fn create_addr(&self) -> &ffi::evmc_address {
+        &self.0.create_address
+    }
+
+    pub fn output(&self) -> Option<&[u8]> {
+        if !self.0.output_data.is_null() && self.0.output_size != 0 {
+            Some(unsafe { slice::from_raw_parts::<u8>(self.0.output_data, self.0.output_size) })
+        } else {
+            None
+        }
+    }
+
+    pub fn status(&self) -> ffi::evmc_status_code {
+        self.0.status_code
+    }
 }
 
 #[no_mangle]
-pub extern "C" fn release_result(result: *const ffi::evmc_result) {
+extern "C" fn release_result(result: *const ffi::evmc_result) {
     unsafe {
         Box::from_raw(result as *mut ffi::evmc_result);
     }