Avoid String::from_utf8 for loads() bytes

Author: ijl

Cargo.lock

@@ -31,6 +31,7 @@ classifier = [
 ]
 
 [dependencies]
+encoding_rs = { version = "0.8", default_features = false }
 itoa = { version = "0.4", default_features = false }
 pyo3 = { path = "./pyo3", features = ["extension-module", "python3"]}
 serde = { version = "1", default_features = false }

Cargo.toml

@@ -28,13 +28,11 @@ pub fn deserialize(py: Python, ptr: *mut pyo3::ffi::PyObject) -> PyResult<PyObje
     } else if unsafe { obj_type_ptr == typeref::BYTES_PTR } {
         let buffer = unsafe { pyo3::ffi::PyBytes_AsString(ptr) as *const u8 };
         let length = unsafe { pyo3::ffi::PyBytes_Size(ptr) as usize };
-        match String::from_utf8(unsafe { std::slice::from_raw_parts(buffer, length).to_vec() }) {
-            Ok(string) => {
-                data = Cow::Owned(string);
-            }
-            Err(_) => {
-                return Err(JSONDecodeError::py_err((INVALID_STR, "", 0)));
-            }
+        let slice = unsafe { std::slice::from_raw_parts(buffer, length) };
+        if encoding_rs::Encoding::utf8_valid_up_to(slice) == length {
+            data = Cow::Borrowed(unsafe { std::str::from_utf8_unchecked(slice) });
+        } else {
+            return Err(JSONDecodeError::py_err((INVALID_STR, "", 0)));
         }
     } else {
         return Err(JSONDecodeError::py_err((
@@ -44,7 +42,7 @@ pub fn deserialize(py: Python, ptr: *mut pyo3::ffi::PyObject) -> PyResult<PyObje
         )));
     }
 
-    let seed = JsonValue{};
+    let seed = JsonValue {};
     let mut deserializer = serde_json::Deserializer::from_str(&data);
     match seed.deserialize(&mut deserializer) {
         Ok(py_ptr) => {

src/decode.rs

@@ -6,6 +6,7 @@
 #[macro_use]
 extern crate pyo3;
 
+extern crate encoding_rs;
 extern crate itoa;
 extern crate serde;
 extern crate serde_json;