update wasm-parser dep; use it for validation

lib/runtime-core/src/lib.rs

@@ -93,13 +93,18 @@ pub fn compile_with_config(
 /// WebAssembly specification. Returns `true` if validation
 /// succeeded, `false` if validation failed.
 pub fn validate(wasm: &[u8]) -> bool {
+    validate_and_report_errors(wasm).is_ok()
+}
+
+/// The same as `validate` but with an Error message on failure
+pub fn validate_and_report_errors(wasm: &[u8]) -> ::std::result::Result<(), String> {
     use wasmparser::WasmDecoder;
     let mut parser = wasmparser::ValidatingParser::new(wasm, None);
     loop {
         let state = parser.read();
         match *state {
-            wasmparser::ParserState::EndWasm => break true,
-            wasmparser::ParserState::Error(_) => break false,
+            wasmparser::ParserState::EndWasm => break Ok(()),
+            wasmparser::ParserState::Error(e) => break Err(format!("{}", e)),
             _ => {}
         }
     }

lib/runtime-core/src/module.rs

@@ -73,7 +73,7 @@ impl ModuleInfo {
                 let len = reader.bytes_remaining();
                 let bytes = reader.read_bytes(len)?;
                 let data = bytes.to_vec();
-                let name = String::from_utf8_lossy(name).to_string();
+                let name = name.to_string();
                 self.custom_sections.insert(name, data);
             }
         }