Add support for seekable wsgi.file_wrapper

1 files changed, 10 insertions, 0 deletions

diff --git a/src/waitress/buffers.py b/src/waitress/buffers.py
index 386eb40..8091ff0 100644
--- a/src/waitress/buffers.py
+++ b/src/waitress/buffers.py
@@ -145,6 +145,16 @@ class ReadOnlyFileBasedBuffer(FileBasedBuffer):
         self.file = file
         self.block_size = block_size  # for __iter__
 
+        # This is for the benefit of anyone that is attempting to wrap this
+        # wsgi.file_wrapper in a WSGI middleware and wants to seek, this is
+        # useful for instance for support Range requests
+        if _is_seekable(self.file):
+            if hasattr(self.file, "seekable"):
+                self.seekable = self.file.seekable
+
+            self.seek = self.file.seek
+            self.tell = self.file.tell
+
     def prepare(self, size=None):
         if _is_seekable(self.file):
             start_pos = self.file.tell()