From 6fc4ca53762a4082e9f6ff0786392c99f8f08d11 Mon Sep 17 00:00:00 2001
From: Oskar Eichler <oskar@songstats.com>
Date: Sun, 30 Aug 2026 02:19:12 +0200
Subject: [PATCH 1/2] Support array response headers in CGI

---
 lib/rackup/handler/cgi.rb | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/lib/rackup/handler/cgi.rb b/lib/rackup/handler/cgi.rb
index a8f8a11..7ba8723 100644
--- a/lib/rackup/handler/cgi.rb
+++ b/lib/rackup/handler/cgi.rb
@@ -40,8 +40,10 @@ def self.serve(app)
       def self.send_headers(status, headers)
         $stdout.print "Status: #{status}\r\n"
         headers.each { |k, vs|
-          vs.split("\n").each { |v|
-            $stdout.print "#{k}: #{v}\r\n"
+          Array(vs).each { |value|
+            value.split("\n").each { |v|
+              $stdout.print "#{k}: #{v}\r\n"
+            }
           }
         }
         $stdout.print "\r\n"

From ec33dd90191fac47958d461ca06c64dad30e7c6a Mon Sep 17 00:00:00 2001
From: Oskar Eichler <oskar@songstats.com>
Date: Sun, 30 Aug 2026 15:09:16 +0700
Subject: [PATCH 2/2] Test array response headers in CGI

---
 test/spec_cgi.rb | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)
 create mode 100644 test/spec_cgi.rb

diff --git a/test/spec_cgi.rb b/test/spec_cgi.rb
new file mode 100644
index 0000000..400bff1
--- /dev/null
+++ b/test/spec_cgi.rb
@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+# Released under the MIT License.
+# Copyright, 2026, by Oskar Eichler.
+
+require_relative 'helper'
+require_relative '../lib/rackup/handler/cgi'
+
+describe Rackup::Handler::CGI do
+  it 'writes string and array response header values' do
+    output = StringIO.new
+    original_stdout = $stdout
+    $stdout = output
+
+    Rackup::Handler::CGI.send_headers(
+      200,
+      'vary' => "accept\norigin",
+      'set-cookie' => ['session=one', 'session=two']
+    )
+
+    output.string.must_equal(
+      "Status: 200\r\n" \
+      "vary: accept\r\n" \
+      "vary: origin\r\n" \
+      "set-cookie: session=one\r\n" \
+      "set-cookie: session=two\r\n\r\n"
+    )
+  ensure
+    $stdout = original_stdout
+  end
+end