Handle \n in MIME::Types.type_for

Resolves #177.

Better handle possible line-termination strings (legal in Unix
filenames) such as `\n` in `MIME::Types.type_for`. Reported by
ooooooo-q.

History.md

@@ -1,5 +1,13 @@
 # Changelog
 
+## 3.5.1 / 2023-08-21
+
+- 1 bug fix:
+
+  - Better handle possible line-termination strings (legal in Unix filenames)
+    such as `\n` in `MIME::Types.type_for`. Reported by ooooooo-q in [#177][],
+    resolved in [#178][].
+
 ## 3.5.0 / 2023-08-07
 
 - 1 minor enhancement:
@@ -304,6 +312,8 @@
 [#166]: https://github.com/mime-types/ruby-mime-types/issues/166
 [#167]: https://github.com/mime-types/ruby-mime-types/pull/167
 [#170]: https://github.com/mime-types/ruby-mime-types/pull/170
+[#177]: https://github.com/mime-types/ruby-mime-types/issues/177
+[#178]: https://github.com/mime-types/ruby-mime-types/pull/178
 [code-of-conduct.md]: Code-of-Conduct_md.html
 [contributor covenant]: http://contributor-covenant.org
 [mime-types-data]: https://github.com/mime-types/mime-types-data

lib/mime/type.rb

@@ -93,7 +93,7 @@ def to_s
   end
 
   # The released version of the mime-types library.
-  VERSION = "3.5.0"
+  VERSION = "3.5.1"
 
   include Comparable
 

lib/mime/types.rb

@@ -152,7 +152,7 @@ def [](type_id, complete: false, registered: false)
   #     => [application/xml, image/gif, text/xml]
   def type_for(filename)
     Array(filename).flat_map { |fn|
-      @extension_index[fn.chomp.downcase[/\.?([^.]*?)$/, 1]]
+      @extension_index[fn.chomp.downcase[/\.?([^.]*?)\z/m, 1]]
     }.compact.inject(Set.new, :+).sort { |a, b|
       a.priority_compare(b)
     }

test/test_mime_types.rb

@@ -159,6 +159,10 @@ def mime_types
       plain_text.add_extensions("xtxt")
       assert_includes mime_types.type_for("xtxt"), "text/plain"
     end
+
+    it "handles newline characters correctly" do
+      assert_includes mime_types.type_for("test.pdf\n.txt"), "text/plain"
+    end
   end
 
   describe "#count" do

test/test_mime_types_class.rb

@@ -100,6 +100,11 @@ def setup
       plain_text.add_extensions("xtxt")
       assert_includes MIME::Types.type_for("xtxt"), "text/plain"
     end
+
+    it "handles newline characters correctly" do
+      assert_includes MIME::Types.type_for("test.pdf\n.txt"), "text/plain"
+      assert_includes MIME::Types.type_for("test.txt\n.pdf"), "application/pdf"
+    end
   end
 
   describe ".count" do