From a95077fd790e32ff576041dba0cb5dedcafc507b Mon Sep 17 00:00:00 2001
From: Tim Craft <mail@timcraft.com>
Date: Mon, 1 Apr 2024 11:11:03 +0100
Subject: [PATCH] Support parsing multiple files for one form field

---
 lib/rack/query_parser.rb      |  6 ++++++
 test/multipart/multiple_files | 16 ++++++++++++++++
 test/spec_multipart.rb        | 12 ++++++++++++
 test/spec_utils.rb            |  2 +-
 4 files changed, 35 insertions(+), 1 deletion(-)
 create mode 100644 test/multipart/multiple_files

diff --git a/lib/rack/query_parser.rb b/lib/rack/query_parser.rb
index 28cbce18f..fff499da8 100644
--- a/lib/rack/query_parser.rb
+++ b/lib/rack/query_parser.rb
@@ -132,6 +132,12 @@ def normalize_params(params, name, v, _depth=nil)
       if after == ''
         if k == '[]' && depth != 0
           return [v]
+        elsif !params[k].nil? && !v.nil? && depth == 0
+          if params[k].is_a?(Array)
+            params[k] << v
+          else
+            params[k] = [params[k], v]
+          end
         else
           params[k] = v
         end
diff --git a/test/multipart/multiple_files b/test/multipart/multiple_files
new file mode 100644
index 000000000..299a08ad0
--- /dev/null
+++ b/test/multipart/multiple_files
@@ -0,0 +1,16 @@
+--AaB03x
+content-disposition: form-data; name="files"; filename="file1.txt"
+content-type: text/plain
+
+foo
+--AaB03x
+content-disposition: form-data; name="files"; filename="file2.txt"
+content-type: text/plain
+
+bar
+--AaB03x
+content-disposition: form-data; name="files"; filename="file3.txt"
+content-type: text/plain
+
+quux
+--AaB03x--
diff --git a/test/spec_multipart.rb b/test/spec_multipart.rb
index 53d8b4d66..34a2bf45b 100644
--- a/test/spec_multipart.rb
+++ b/test/spec_multipart.rb
@@ -518,6 +518,18 @@ def initialize(*)
     params["files"].size.must_equal 252
   end
 
+  it "parses multiple files with same name" do
+    env = Rack::MockRequest.env_for("/", multipart_fixture(:multiple_files))
+    params = Rack::Multipart.parse_multipart(env)
+    params["files"].must_be_instance_of Array
+    params["files"][0][:filename].must_equal "file1.txt"
+    params["files"][0][:tempfile].read.must_equal "foo"
+    params["files"][1][:filename].must_equal "file2.txt"
+    params["files"][1][:tempfile].read.must_equal "bar"
+    params["files"][2][:filename].must_equal "file3.txt"
+    params["files"][2][:tempfile].read.must_equal "quux"
+  end
+
   it "parses IE multipart upload and cleans up the filename" do
     env = Rack::MockRequest.env_for("/", multipart_fixture(:ie))
     params = Rack::Multipart.parse_multipart(env)
diff --git a/test/spec_utils.rb b/test/spec_utils.rb
index 4111bdb84..37d9ec460 100644
--- a/test/spec_utils.rb
+++ b/test/spec_utils.rb
@@ -150,7 +150,7 @@ def assert_nested_query(exp, act)
       must_equal "foo" => "\"bar\""
 
     Rack::Utils.parse_nested_query("foo=bar&foo=quux").
-      must_equal "foo" => "quux"
+      must_equal "foo" => ["bar", "quux"]
     Rack::Utils.parse_nested_query("foo&foo=").
       must_equal "foo" => ""
     Rack::Utils.parse_nested_query("foo=1&bar=2").