From 62d4ea24173ab70b1e52b3b8c187c5238ce05a29 Mon Sep 17 00:00:00 2001
From: Illia Batozskyi <ivz@amazon.com>
Date: Thu, 21 Jan 2021 15:55:50 -0500
Subject: [PATCH] Fall back to Transfer-Encoding 'chunked' if AWSRequest body
 is not seekable stream

---
 botocore/awsrequest.py   | 19 +++++++++++++------
 tests/unit/test_utils.py | 15 +++++++++++++++
 2 files changed, 28 insertions(+), 6 deletions(-)

diff --git a/botocore/awsrequest.py b/botocore/awsrequest.py
index 535b91bed4..f47f0cc01e 100644
--- a/botocore/awsrequest.py
+++ b/botocore/awsrequest.py
@@ -11,6 +11,7 @@
 # distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF
 # ANY KIND, either express or implied. See the License for the specific
 # language governing permissions and limitations under the License.
+import io
 import sys
 import logging
 import functools
@@ -404,12 +405,18 @@ def _determine_content_length(self, body):
 
         # Try getting the length from a seekable stream
         if hasattr(body, 'seek') and hasattr(body, 'tell'):
-            orig_pos = body.tell()
-            body.seek(0, 2)
-            end_file_pos = body.tell()
-            body.seek(orig_pos)
-            return end_file_pos - orig_pos
-
+            try:
+                orig_pos = body.tell()
+                body.seek(0, 2)
+                end_file_pos = body.tell()
+                body.seek(orig_pos)
+                return end_file_pos - orig_pos
+            except io.UnsupportedOperation:
+                # in case when body is, for example, io.BufferedIOBase object
+                # it has "seek" method which throws "UnsupportedOperation"
+                # exception in such case we want to fall back to "chunked"
+                # encoding
+                pass
         # Failed to determine the length
         return None
 
diff --git a/tests/unit/test_utils.py b/tests/unit/test_utils.py
index d55f03f8ba..9dd8fd7858 100644
--- a/tests/unit/test_utils.py
+++ b/tests/unit/test_utils.py
@@ -10,6 +10,8 @@
 # distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF
 # ANY KIND, either express or implied. See the License for the specific
 # language governing permissions and limitations under the License.
+import io
+
 from tests import unittest
 from tests import RawResponse
 from dateutil.tz import tzutc, tzoffset
@@ -918,6 +920,19 @@ def test_is_unaffected_by_sigv4(self):
                          'https://bucket.s3.amazonaws.com/key.txt')
 
 
+class TestSwitchToChunkedEncodingForNonSeekableObjects(unittest.TestCase):
+    def test_switch_to_chunked_encodeing_for_stream_like_object(self):
+        request = AWSRequest(
+            method='POST', headers={},
+            data=io.BufferedIOBase(b"some initial binary data"),
+            url='https://foo.amazonaws.com/bucket/key.txt'
+        )
+        prepared_request = request.prepare()
+        self.assertEqual(
+            prepared_request.headers, {'Transfer-Encoding': 'chunked'}
+        )
+
+
 class TestInstanceCache(unittest.TestCase):
     class DummyClass(object):
         def __init__(self, cache):