Fix form response file saving

src/quart_trio/datastructures.py

@@ -0,0 +1,26 @@
+from __future__ import annotations
+
+from os import PathLike
+
+from quart.datastructures import FileStorage
+from trio import open_file, Path, wrap_file
+
+
+class TrioFileStorage(FileStorage):
+    async def save(self, destination: PathLike, buffer_size: int = 16384) -> None:  # type: ignore
+        wrapped_stream = wrap_file(self.stream)
+        async with await open_file(destination, "wb") as file_:
+            data = await wrapped_stream.read(buffer_size)
+            while data != b"":
+                await file_.write(data)
+                data = await wrapped_stream.read(buffer_size)
+
+    async def load(self, source: PathLike, buffer_size: int = 16384) -> None:
+        path = Path(source)
+        self.filename = path.name
+        wrapped_stream = wrap_file(self.stream)
+        async with await open_file(path, "rb") as file_:
+            data = await file_.read(buffer_size)
+            while data != b"":
+                await wrapped_stream.write(data)
+                data = await file_.read(buffer_size)

src/quart_trio/formparser.py

@@ -0,0 +1,7 @@
+from quart.formparser import FormDataParser
+
+from quart_trio.datastructures import TrioFileStorage
+
+
+class TrioFormDataParser(FormDataParser):
+    file_storage_class = TrioFileStorage

src/quart_trio/wrappers/request.py

@@ -4,6 +4,8 @@
 from quart.wrappers.request import Body, Request
 from werkzeug.exceptions import RequestEntityTooLarge, RequestTimeout
 
+from ..formparser import TrioFormDataParser
+
 
 class EventWrapper:
     def __init__(self) -> None:
@@ -44,6 +46,7 @@ def __init__(
 
 class TrioRequest(Request):
     body_class = TrioBody
+    form_data_parser_class = TrioFormDataParser
     lock_class = trio.Lock  # type: ignore
 
     async def get_data(