fix(upload): preserve fields in multipart fallback

- Recover regular multipart fields when the file part is not exposed through request.files.

- Preserve expires and note values for browser uploads that need body-based file recovery.

- Add parser coverage for file parts without filenames and recovered expiry fields.

- Extend upload route tests to assert recovered uploads keep expiry metadata.

- Bump NanoShare to 1.27.3.

my_modules/upload_content.py

@@ -0,0 +1,71 @@
+from __future__ import annotations
+
+from dataclasses import dataclass, field
+from io import BytesIO
+
+from quart.datastructures import FileStorage
+from werkzeug.datastructures import Headers
+from werkzeug.http import parse_options_header
+from werkzeug.sansio.multipart import Data, Epilogue, Field, File, NeedData, MultipartDecoder
+
+@dataclass
+class MultipartUploadParts:
+  fields: dict[str, str] = field(default_factory=dict)
+  file: FileStorage | None = None
+
+def _content_type(headers: Headers) -> str:
+  return headers.get('content-type') or 'application/octet-stream'
+
+def _fallback_filename(headers: Headers, default: str = 'file') -> str:
+  disposition = headers.get('content-disposition', '')
+  _, options = parse_options_header(disposition)
+  filename = options.get('filename')
+  return filename if filename is not None else default
+
+def parse_multipart_upload_body(body: bytes, boundary: str | bytes | None, file_field_name: str = 'file') -> MultipartUploadParts:
+  parts = MultipartUploadParts()
+  if not body or not boundary:
+    return parts
+
+  boundary_bytes = boundary.encode() if isinstance(boundary, str) else boundary
+  parser = MultipartDecoder(boundary_bytes)
+  parser.receive_data(body)
+  parser.receive_data(None)
+
+  current_part = None
+  current_chunks: list[bytes] = []
+
+  while True:
+    event = parser.next_event()
+    if isinstance(event, (Epilogue, NeedData)):
+      break
+    if isinstance(event, (Field, File)):
+      current_part = event
+      current_chunks = []
+      continue
+    if not isinstance(event, Data) or current_part is None:
+      continue
+
+    current_chunks.append(event.data)
+    if event.more_data:
+      continue
+
+    data = b''.join(current_chunks)
+    if current_part.name == file_field_name and data:
+      headers = current_part.headers
+      parts.file = FileStorage(
+        stream=BytesIO(data),
+        filename=getattr(current_part, 'filename', None) or _fallback_filename(headers),
+        name=file_field_name,
+        content_type=_content_type(headers),
+        headers=headers,
+      )
+    elif isinstance(current_part, Field):
+      _, options = parse_options_header(current_part.headers.get('content-type', ''))
+      charset = options.get('charset') or 'utf-8'
+      parts.fields[current_part.name] = data.decode(charset, 'replace')
+
+  return parts
+
+def recover_file_from_multipart_body(body: bytes, boundary: str | bytes | None, field_name: str = 'file') -> FileStorage | None:
+  return parse_multipart_upload_body(body, boundary, field_name).file