archives: add code for detecting .rar and .7z files.

app/logical/file_type_detector.rb

@@ -55,8 +55,33 @@ class FileTypeDetector
     # https://aomediacodec.github.io/av1-avif/#brands-overview
     when /\A....ftyp(?:avif|avis)/
       :avif
+
+    # https://www.loc.gov/preservation/digital/formats/fdd/fdd000354.shtml#sign
+    # https://en.wikipedia.org/wiki/ZIP_(file_format)
+    # XXX Does not detect self-extracting archives
     when /\APK\x03\x04/
       :zip
+
+    # https://docs.fileformat.com/compression/7z/#file-signature
+    # https://py7zr.readthedocs.io/en/latest/archive_format.html#signature
+    # https://www.loc.gov/preservation/digital/formats/fdd/fdd000539.shtml#sign
+    # https://en.wikipedia.org/wiki/7z
+    # XXX Does not detect self-extracting archives
+    when /\A7z\xbc\xaf\x27\x1c/n
+      :"7z"
+
+    # Rar 1.5 to 4.0
+    # https://www.rarlab.com/technote.htm#rarsign
+    # https://www.loc.gov/preservation/digital/formats/fdd/fdd000450.shtml#sign
+    # https://en.wikipedia.org/wiki/RAR_(file_format)
+    # XXX Does not detect self-extracting archives
+    when /\ARar!\x1a\x07\x00/n
+      :rar
+
+    # Rar 5.0+
+    when /\ARar!\x1a\x07\x01\x00/n
+      :rar
+
     else
       :bin
     end

test/unit/danbooru_archive_test.rb

@@ -75,6 +75,27 @@ class DanbooruArchiveTest < ActiveSupport::TestCase
           filenames.each { |filename| assert_equal(true, File.exist?(filename)) }
         end
       end
+
+      should "work with a .zip file" do
+        Danbooru::Archive.extract!("test/files/archive/ugoira.zip") do |dir, filenames|
+          assert_equal(5, filenames.size)
+          filenames.each { |filename| assert_equal(true, File.exist?(filename)) }
+        end
+      end
+
+      should "work with a .rar file" do
+        Danbooru::Archive.extract!("test/files/archive/ugoira.rar") do |dir, filenames|
+          assert_equal(5, filenames.size)
+          filenames.each { |filename| assert_equal(true, File.exist?(filename)) }
+        end
+      end
+
+      should "work with a .7z file" do
+        Danbooru::Archive.extract!("test/files/archive/ugoira.7z") do |dir, filenames|
+          assert_equal(5, filenames.size)
+          filenames.each { |filename| assert_equal(true, File.exist?(filename)) }
+        end
+      end
     end
 
     context "#uncompressed_size method" do
@@ -92,9 +113,20 @@ class DanbooruArchiveTest < ActiveSupport::TestCase
     end
 
     context "#format method" do
-      should "work" do
-        archive = Danbooru::Archive.open!("test/files/ugoira.zip")
-        assert_equal("ZIP 2.0 (uncompressed)", archive.format)
+      should "detect the file type" do
+        assert_equal("ZIP 2.0 (uncompressed)", Danbooru::Archive.open("test/files/archive/ugoira.zip").format)
+        assert_equal("RAR5", Danbooru::Archive.open("test/files/archive/ugoira.rar").format)
+        assert_equal("7-Zip", Danbooru::Archive.open("test/files/archive/ugoira.7z").format)
+        assert_equal("7-Zip", Danbooru::Archive.open("test/files/archive/ugoira.tar.7z").format)
+      end
+    end
+
+    context "#file_ext method" do
+      should "detect the file extension" do
+        assert_equal(:zip, Danbooru::Archive.open("test/files/archive/ugoira.zip").file_ext)
+        assert_equal(:rar, Danbooru::Archive.open("test/files/archive/ugoira.rar").file_ext)
+        assert_equal(:"7z", Danbooru::Archive.open("test/files/archive/ugoira.7z").file_ext)
+        assert_equal(:"7z", Danbooru::Archive.open("test/files/archive/ugoira.tar.7z").file_ext)
       end
     end