From d1b23a1900d5ccc2aae56c4bb475f9640cb9a455 Mon Sep 17 00:00:00 2001
From: Bert JW Regeer <bertjw@regeer.org>
Date: Mon, 17 Jan 2022 16:17:52 -0700
Subject: [PATCH 1/3] Add tests to validate wsgi.file_wrapper seek/tell are
 added

---
 tests/test_buffers.py | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tests/test_buffers.py b/tests/test_buffers.py
index 01cdc2de..b37949b8 100644
--- a/tests/test_buffers.py
+++ b/tests/test_buffers.py
@@ -185,6 +185,8 @@ def tearDown(self):
     def test_prepare_not_seekable(self):
         f = KindaFilelike(b"abc")
         inst = self._makeOne(f)
+        self.assertFalse(hasattr(inst, "seek"))
+        self.assertFalse(hasattr(inst, "tell"))
         result = inst.prepare()
         self.assertEqual(result, False)
         self.assertEqual(inst.remain, 0)
@@ -200,6 +202,8 @@ def test_prepare_not_seekable_closeable(self):
     def test_prepare_seekable_closeable(self):
         f = Filelike(b"abc", close=1, tellresults=[0, 10])
         inst = self._makeOne(f)
+        self.assertEqual(inst.seek, f.seek)
+        self.assertEqual(inst.tell, f.tell)
         result = inst.prepare()
         self.assertEqual(result, 10)
         self.assertEqual(inst.remain, 10)

From 8423ffac8f2f32ed501d225f9f4f6893511212a7 Mon Sep 17 00:00:00 2001
From: Bert JW Regeer <bertjw@regeer.org>
Date: Mon, 17 Jan 2022 16:19:29 -0700
Subject: [PATCH 2/3] Add support for seekable wsgi.file_wrapper

---
 src/waitress/buffers.py | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/waitress/buffers.py b/src/waitress/buffers.py
index 386eb40f..8091ff0e 100644
--- a/src/waitress/buffers.py
+++ b/src/waitress/buffers.py
@@ -145,6 +145,16 @@ def __init__(self, file, block_size=32768):
         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()

From 5627a4c322ae02c79bb61e531fc6bf8e0a69c9b8 Mon Sep 17 00:00:00 2001
From: Bert JW Regeer <bertjw@regeer.org>
Date: Mon, 17 Jan 2022 16:24:56 -0700
Subject: [PATCH 3/3] Add CHANGELOG for wsgi.file_wrapper seek/tell attrs

---
 CHANGES.txt | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/CHANGES.txt b/CHANGES.txt
index 5ccaa642..888c31b5 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -11,6 +11,13 @@ Python Version Support
 Bugfix
 ~~~~~~
 
+- ``wsgi.file_wrapper`` now sets the ``seekable``, ``seek``, and ``tell`` attributes from
+  the underlying file if the underlying file is seekable. This allows WSGI
+  middleware to implement things like range requests for example
+
+  See https://github.com/Pylons/waitress/issues/359 and
+  https://github.com/Pylons/waitress/pull/363
+
 - In Python 3 ``OSError`` is no longer subscriptable, this caused failures on
   Windows attempting to loop to find an socket that would work for use in the
   trigger.