Fixed #30422 -- Made TemporaryFileUploadHandler handle interrupted uploads.

This patch allows upload handlers to handle interrupted uploads.

Co-Authored-By: Mariusz Felisiak <felisiak.mariusz@gmail.com>

django/core/files/uploadhandler.py

@@ -1,7 +1,7 @@
 """
 Base file upload handler classes, and the built-in concrete subclasses
 """
-
+import os
 from io import BytesIO
 
 from django.conf import settings
@@ -127,6 +127,13 @@ class FileUploadHandler:
         """
         pass
 
+    def upload_interrupted(self):
+        """
+        Signal that the upload was interrupted. Subclasses should perform
+        cleanup that is necessary for this handler.
+        """
+        pass
+
 
 class TemporaryFileUploadHandler(FileUploadHandler):
     """
@@ -147,6 +154,15 @@ class TemporaryFileUploadHandler(FileUploadHandler):
         self.file.size = file_size
         return self.file
 
+    def upload_interrupted(self):
+        if hasattr(self, 'file'):
+            temp_location = self.file.temporary_file_path()
+            try:
+                self.file.close()
+                os.remove(temp_location)
+            except FileNotFoundError:
+                pass
+
 
 class MemoryFileUploadHandler(FileUploadHandler):
     """

django/http/multipartparser.py

@@ -150,6 +150,8 @@ class MultiPartParser:
         num_post_keys = 0
         # To limit the amount of data read from the request.
         read_size = None
+        # Whether a file upload is finished.
+        uploaded_file = True
 
         try:
             for item_type, meta_data, field_stream in Parser(stream, self._boundary):
@@ -159,6 +161,7 @@ class MultiPartParser:
                     # we hit the next boundary/part of the multipart content.
                     self.handle_file_complete(old_field_name, counters)
                     old_field_name = None
+                    uploaded_file = True
 
                 try:
                     disposition = meta_data['content-disposition'][1]
@@ -225,6 +228,7 @@ class MultiPartParser:
                         content_length = None
 
                     counters = [0] * len(handlers)
+                    uploaded_file = False
                     try:
                         for handler in handlers:
                             try:
@@ -279,6 +283,9 @@ class MultiPartParser:
             if not e.connection_reset:
                 exhaust(self._input_data)
         else:
+            if not uploaded_file:
+                for handler in handlers:
+                    handler.upload_interrupted()
             # Make sure that the request data is all fed
             exhaust(self._input_data)
 

docs/ref/files/uploads.txt

@@ -212,6 +212,13 @@ attributes:
 
     Callback signaling that the entire upload (all files) has completed.
 
+.. method:: FileUploadHandler.upload_interrupted()
+
+    .. versionadded:: 3.2
+
+    Callback signaling that the upload was interrupted, e.g. when the user
+    closed their browser during file upload.
+
 .. method:: FileUploadHandler.handle_raw_input(input_data, META, content_length, boundary, encoding)
 
     Allows the handler to completely override the parsing of the raw

docs/releases/3.2.txt

@@ -195,8 +195,9 @@ File Storage
 File Uploads
 ~~~~~~~~~~~~
 
-* ...
+* The new :meth:`FileUploadHandler.upload_interrupted()
-
+  <django.core.files.uploadhandler.FileUploadHandler.upload_interrupted>`
+  callback allows handling interrupted uploads.
 
 Forms
 ~~~~~

tests/file_uploads/tests.py

@@ -6,12 +6,13 @@ import sys
 import tempfile as sys_tempfile
 import unittest
 from io import BytesIO, StringIO
+from unittest import mock
 from urllib.parse import quote
 
 from django.core.files import temp as tempfile
 from django.core.files.uploadedfile import SimpleUploadedFile
 from django.http.multipartparser import (
-    MultiPartParser, MultiPartParserError, parse_header,
+    FILE, MultiPartParser, MultiPartParserError, Parser, parse_header,
 )
 from django.test import SimpleTestCase, TestCase, client, override_settings
 
@@ -443,6 +444,30 @@ class FileUploadTests(TestCase):
             temp_path = response.json()['temp_path']
             self.assertIs(os.path.exists(temp_path), False)
 
+    def test_upload_interrupted_temporary_file_handler(self):
+        # Simulate an interrupted upload by omitting the closing boundary.
+        class MockedParser(Parser):
+            def __iter__(self):
+                for item in super().__iter__():
+                    item_type, meta_data, field_stream = item
+                    yield item_type, meta_data, field_stream
+                    if item_type == FILE:
+                        return
+
+        with tempfile.NamedTemporaryFile() as temp_file:
+            temp_file.write(b'a')
+            temp_file.seek(0)
+            with mock.patch(
+                'django.http.multipartparser.Parser',
+                MockedParser,
+            ):
+                response = self.client.post(
+                    '/temp_file/upload_interrupted/',
+                    {'file': temp_file},
+                )
+            temp_path = response.json()['temp_path']
+            self.assertIs(os.path.exists(temp_path), False)
+
     def test_fileupload_getlist(self):
         file = tempfile.NamedTemporaryFile
         with file() as file1, file() as file2, file() as file2a:

tests/file_uploads/urls.py

@@ -14,6 +14,7 @@ urlpatterns = [
     path('getlist_count/', views.file_upload_getlist_count),
     path('upload_errors/', views.file_upload_errors),
     path('temp_file/stop_upload/', views.file_stop_upload_temporary_file),
+    path('temp_file/upload_interrupted/', views.file_upload_interrupted_temporary_file),
     path('filename_case/', views.file_upload_filename_case_view),
     re_path(r'^fd_closing/(?P<access>t|f)/$', views.file_upload_fd_closing),
 ]

tests/file_uploads/views.py

@@ -2,6 +2,7 @@ import hashlib
 import os
 
 from django.core.files.uploadedfile import UploadedFile
+from django.core.files.uploadhandler import TemporaryFileUploadHandler
 from django.http import HttpResponse, HttpResponseServerError, JsonResponse
 
 from .models import FileModel
@@ -112,6 +113,15 @@ def file_stop_upload_temporary_file(request):
     )
 
 
+def file_upload_interrupted_temporary_file(request):
+    request.upload_handlers.insert(0, TemporaryFileUploadHandler())
+    request.upload_handlers.pop(2)
+    request.FILES  # Trigger file parsing.
+    return JsonResponse(
+        {'temp_path': request.upload_handlers[0].file.temporary_file_path()},
+    )
+
+
 def file_upload_getlist_count(request):
     """
     Check the .getlist() function to ensure we receive the correct number of files.