https://github.com/macournoyer/thin/commit/829c3aaa48efcd0c289d856f068f5d0fb16edaac

From 829c3aaa48efcd0c289d856f068f5d0fb16edaac Mon Sep 17 00:00:00 2001
From: Vasily Fedoseyev <github@vasfed.ru>
Date: Wed, 1 Feb 2023 00:03:48 +0300
Subject: [PATCH] Update code base for Ruby v3.2 (#392)

* `File.exists?` is removed in ruby 3.2

* Fix deprecated rspec expectation syntax

* Fix `Socket.gethostbyname` deprecation

* Test on ruby 3.2 and rack 2.
--- a/lib/thin/backends/swiftiply_client.rb
+++ b/lib/thin/backends/swiftiply_client.rb
@@ -50,7 +50,17 @@ def swiftiply_handshake(key)
 
       # For some reason Swiftiply request the current host
       def host_ip
-        Socket.gethostbyname(@backend.host)[3].unpack('CCCC') rescue [0, 0, 0, 0]
+        begin
+          if defined?(Addrinfo)
+            # ruby 2.0+
+            # TODO: ipv6 support here?
+            Addrinfo.getaddrinfo(@backend.host, @backend.port, :PF_INET, :STREAM).first.ip_address.split('.').map(&:to_i)
+          else
+            Socket.gethostbyname(@backend.host)[3].unpack('CCCC')
+          end
+        rescue
+          [0, 0, 0, 0]
+        end
       end
   end
 end
\ No newline at end of file
--- a/lib/thin/daemonizing.rb
+++ b/lib/thin/daemonizing.rb
@@ -78,7 +78,7 @@ def change_privilege(user, group=user)
 
       if uid != target_uid || gid != target_gid
         # Change PID file ownership
-        File.chown(target_uid, target_gid, @pid_file) if File.exists?(@pid_file)
+        File.chown(target_uid, target_gid, @pid_file) if File.exist?(@pid_file)
 
         # Change process ownership
         Process.initgroups(user, target_gid)
@@ -174,7 +174,7 @@ def read_pid_file(file)
     
     protected
       def remove_pid_file
-        File.delete(@pid_file) if @pid_file && File.exists?(@pid_file)
+        File.delete(@pid_file) if @pid_file && File.exist?(@pid_file)
       end
     
       def write_pid_file
--- a/spec/connection_spec.rb
+++ b/spec/connection_spec.rb
@@ -37,7 +37,7 @@
   end
 
   it "should process at most once when request is larger than expected" do
-    @connection.should_receive(:process).at_most(1)
+    expect(@connection).to receive(:process).at_most(1)
     @connection.receive_data("POST / HTTP/1.1\r\nHost: localhost:3000\r\nContent-Length: 300\r\n\r\n")
     10.times { @connection.receive_data('X' * 1_000) }
   end
--- a/spec/rails_app/config/boot.rb
+++ b/spec/rails_app/config/boot.rb
@@ -26,7 +26,7 @@ def vendor_rails?
 
     # FIXME : Ruby 1.9
     def preinitialize
-      load(preinitializer_path) if File.exists?(preinitializer_path)
+      load(preinitializer_path) if File.exist?(preinitializer_path)
     end
 
     def preinitializer_path
--- a/spec/request/parser_spec.rb
+++ b/spec/request/parser_spec.rb
@@ -210,7 +210,7 @@
   end
 
   it "should fail when total request vastly exceeds specified CONTENT_LENGTH" do
-    proc do
+    expect do
       R(<<-EOS, true)
 POST / HTTP/1.1
 Host: localhost:3000
@@ -218,7 +218,7 @@
 
 #{'X' * 300_000}
 EOS
-    end.should raise_error(InvalidRequest)
+    end.to raise_error(InvalidRequest)
   end
 
   it "should default SERVER_NAME to localhost" do