From cc60aaa83503ae611a7fe825abced22fe8bfa01d Mon Sep 17 00:00:00 2001
From: Kadir Can Ozden <101993364+bysiber@users.noreply.github.com>
Date: Fri, 20 Feb 2026 17:17:03 +0300
Subject: [PATCH] Fix QuerystringParser._internal_write returning len(data)
 instead of length

When max_size truncation occurs, write() passes a smaller length
to _internal_write which only processes that many bytes. But
_internal_write returns len(data) (the original untrunated size),
inflating _current_size tracking and returning a misleading byte
count to the caller.

MultipartParser._internal_write correctly returns length. This
makes QuerystringParser consistent.
---
 python_multipart/multipart.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/python_multipart/multipart.py b/python_multipart/multipart.py
index 1489b7a..9da99e3 100644
--- a/python_multipart/multipart.py
+++ b/python_multipart/multipart.py
@@ -936,7 +936,7 @@ def _internal_write(self, data: bytes, length: int) -> int:
 
         self.state = state
         self._found_sep = found_sep
-        return len(data)
+        return length
 
     def finalize(self) -> None:
         """Finalize this parser, which signals to that we are finished parsing,