uploads: fix corrupted image detection.

* Fix corrupted image detection. We were shelling out to vips and trying
  to grep for error messages, but the error message for jpeg files changed.
  Now we load the file in ruby vips, which raises an error on failure.

* Don't attempt to redownload corrupted images. If a download completes
  without any errors yet the downloaded file is corrupt, then something is
  wrong at the source and redownloading is unlikely to help. Let the
  upload fail and the user retry if necessary.

* Validate that all uploads are uncorrupted, including files uploaded
  from a computer, not just files uploaded from a source.

test/test_helpers/upload_test_helper.rb

@@ -1,4 +1,8 @@
 module UploadTestHelper
+  def upload_from_file(filepath)
+    UploadService.new(file: upload_file(filepath)).start!
+  end
+
   def upload_file(path)
     file = Tempfile.new(binmode: true)
     IO.copy_stream("#{Rails.root}/#{path}", file.path)

test/unit/upload_service_test.rb

@@ -34,28 +34,6 @@ class UploadServiceTest < ActiveSupport::TestCase
         end
       end
 
-      context "for a corrupt jpeg" do
-        setup do
-          @source = "https://cdn.donmai.us/original/93/f4/93f4dd66ef1eb11a89e56d31f9adc8d0.jpg"
-          @mock_upload = mock("upload")
-          @mock_upload.stubs(:source_url).returns(@source)
-          @mock_upload.stubs(:referer_url).returns(nil)
-          @bad_file = File.open("#{Rails.root}/test/files/test-corrupt.jpg", "rb")
-          Downloads::File.any_instance.stubs(:download!).returns([@bad_file, nil])
-        end
-
-        teardown do
-          @bad_file.close
-        end
-
-        should "retry three times" do
-          DanbooruImageResizer.expects(:validate_shell).times(4).returns(false)
-          assert_raise(UploadService::Utils::CorruptFileError) do
-            subject.get_file_for_upload(@mock_upload)
-          end
-        end
-      end
-
       context "for a pixiv" do
         setup do
           @source = "http://www.pixiv.net/member_illust.php?mode=medium&illust_id=62247350"
@@ -1133,6 +1111,33 @@ class UploadServiceTest < ActiveSupport::TestCase
         assert_equal("http://www.example.com", @upload.source)
       end
     end
+
+    context "for a corrupted image" do
+      should "fail for a corrupted jpeg" do
+        @bad_jpeg_path = "test/files/test-corrupt.jpg"
+
+        upload = upload_from_file(@bad_jpeg_path)
+        assert_match(/corrupt/, upload.status)
+        assert_equal(true, UploadService::Utils.corrupt?(@bad_jpeg_path))
+      end
+
+      should "fail for a corrupted gif" do
+        @bad_gif_path = "test/files/test-corrupt.gif"
+
+        upload = upload_from_file(@bad_gif_path)
+        assert_match(/corrupt/, upload.status)
+        assert_equal(true, UploadService::Utils.corrupt?(@bad_gif_path))
+      end
+
+      # https://schaik.com/pngsuite/pngsuite_xxx_png.html
+      should "fail for a corrupted png" do
+        @bad_png_path = "test/files/test-corrupt.png"
+
+        upload = upload_from_file(@bad_png_path)
+        assert_match(/corrupt/, upload.status)
+        assert_equal(true, UploadService::Utils.corrupt?(@bad_png_path))
+      end
+    end
   end
 
   context "#create_post_from_upload" do