Ticket #15644: django.core.files.base.File.diff

django/core/files/base.py

@@ -36 +36 @@
         if not hasattr(self, '_size'):
             if hasattr(self.file, 'size'):
                 self._size = self.file.size
-            elif os.path.exists(self.file.name):
+            elif hasattr(self.file, 'name') and os.path.exists(self.file.name):
                 self._size = os.path.getsize(self.file.name)
+            elif hasattr(self.file, 'tell') and hasattr(self.file, 'seek'):
+                pos = self.file.tell()
+                self.file.seek(0,os.SEEK_END)
+                self._size = self.file.tell()
+                self.file.seek(pos)
             else:
                 raise AttributeError("Unable to determine the file's size.")
         return self._size