Rewind IO during initialization (#3347)

Author: richardwang1124

build_tools/services.rb

@@ -9,10 +9,10 @@ class ServiceEnumerator
     MANIFEST_PATH = File.expand_path('../../services.json', __FILE__)
 
     # Minimum `aws-sdk-core` version for new gem builds
-    MINIMUM_CORE_VERSION = "3.241.3"
+    MINIMUM_CORE_VERSION = "3.241.4"
 
     # Minimum `aws-sdk-core` version for new S3 gem builds
-    MINIMUM_CORE_VERSION_S3 = "3.241.3"
+    MINIMUM_CORE_VERSION_S3 = "3.241.4"
 
     EVENTSTREAM_PLUGIN = "Aws::Plugins::EventStreamConfiguration"
 

gems/aws-sdk-core/CHANGELOG.md

@@ -1,6 +1,8 @@
 Unreleased Changes
 ------------------
 
+* Issue - Rewind IO during initialization for `AwsChunkedTrailerDigestIO`.
+
 3.241.3 (2026-01-08)
 ------------------
 

gems/aws-sdk-core/lib/aws-sdk-core/plugins/checksum_algorithm.rb

@@ -485,6 +485,7 @@ class AwsChunkedTrailerDigestIO
 
         def initialize(options = {})
           @io = options.delete(:io)
+          @io.rewind if @io.respond_to?(:rewind)
           @location_name = options.delete(:location_name)
           @algorithm = options.delete(:algorithm)
           @digest = ChecksumAlgorithm.digest_for_algorithm(@algorithm)

gems/aws-sdk-core/spec/aws/plugins/checksum_algorithm_spec.rb

@@ -479,6 +479,22 @@ def stub_client(client)
           expect(resp.context[:http_checksum][:validated]).to eq('CRC32')
         end
       end
+
+      describe 'AwsChunkedTrailerDigestIO' do
+        it 'rewinds IO on initialization' do
+          io = StringIO.new('hello world')
+          io.read # move to EOF
+          expect(io.pos).to eq(11)
+
+          ChecksumAlgorithm::AwsChunkedTrailerDigestIO.new(
+            io: io,
+            algorithm: 'CRC32',
+            location_name: 'x-amz-checksum-crc32'
+          )
+
+          expect(io.pos).to eq(0)
+        end
+      end
     end
   end
 end