ActiveStorage chokes on BMP data, raises ActiveStorage::InvariableError

[gorj-tessella]

Use TIFF data with ActiveStorage (any variation - LZW-Compressed or not, Alpha or not) and call .variant on the data. See similar issue for TIFF at #34698

Steps to reproduce

Use BMP data with ActiveStorage and call .variant on the data

Expected behavior

Variant should be returned

Actual behavior

ActiveStorage::InvariableError is raised

System configuration

Rails version: 5.2

Ruby version: N/A

[bparanj]

Here are the steps to reproduce this problem:

$ rails c
Loading development environment (Rails 5.2.3)
2.6.1 :001 > path = Pathname.new(File.join('/Users/bparanj/Downloads/', 'w3c_home.bmp'))
 => #<Pathname:/Users/bparanj/Downloads/w3c_home.bmp> 
2.6.1 :002 > io = path.open
 => #<File:/Users/bparanj/Downloads/w3c_home.bmp> 
2.6.1 :003 > filename = 'w3c_home.bmp'
 => "w3c_home.bmp" 
2.6.1 :004 > content_type = 'image/bmp'
 => "image/bmp" 
2.6.1 :005 > ActiveStorage::Blob.create_after_upload! io: io, filename: filename, content_type: content_type, metadata: nil
  Disk Storage (0.8ms) Uploaded file to key: HY23A2VzetwsgHf5qgzLxCaq (checksum: u81qf8b5juN4+dJjHb7fyQ==)
   (0.1ms)  begin transaction
  ActiveStorage::Blob Create (0.3ms)  INSERT INTO "active_storage_blobs" ("key", "filename", "content_type", "metadata", "byte_size", "checksum", "created_at") VALUES (?, ?, ?, ?, ?, ?, ?)  [["key", "HY23A2VzetwsgHf5qgzLxCaq"], ["filename", "w3c_home.bmp"], ["content_type", "image/bmp"], ["metadata", "{\"identified\":true}"], ["byte_size", 10422], ["checksum", "u81qf8b5juN4+dJjHb7fyQ=="], ["created_at", "2019-04-12 16:54:33.238697"]]
   (0.6ms)  commit transaction
 => #<ActiveStorage::Blob id: 1, key: "HY23A2VzetwsgHf5qgzLxCaq", filename: "w3c_home.bmp", content_type: "image/bmp", metadata: {"identified"=>true}, byte_size: 10422, checksum: "u81qf8b5juN4+dJjHb7fyQ==", created_at: "2019-04-12 16:54:33"> 

2.6.1 :007 > as = ActiveStorage::Blob.first
  ActiveStorage::Blob Load (0.2ms)  SELECT  "active_storage_blobs".* FROM "active_storage_blobs" ORDER BY "active_storage_blobs"."id" ASC LIMIT ?  [["LIMIT", 1]]
 => #<ActiveStorage::Blob id: 1, key: "HY23A2VzetwsgHf5qgzLxCaq", filename: "w3c_home.bmp", content_type: "image/bmp", metadata: {"identified"=>true}, byte_size: 10422, checksum: "u81qf8b5juN4+dJjHb7fyQ==", created_at: "2019-04-12 16:54:33"> 

2.6.1 :012 > as.variant(resize: "100x100")
Traceback (most recent call last):
        2: from (irb):12
        1: from (irb):12:in `rescue in irb_binding'
ActiveStorage::InvariableError (ActiveStorage::InvariableError)

Sample bmp image used can be found here: https://www.w3.org/People/mimasa/test/imgformat/. The blob is not variable:

2.6.1 :013 > as.variable?
 => false 

According to the ImageMagick docs: https://imagemagick.org/script/formats.php. It supports bmp image. Currently ActiveStorage::Engine only supports:

    config.active_storage.variable_content_types = %w(
      image/png
      image/gif
      image/jpg
      image/jpeg
      image/pjpeg
      image/tiff
      image/vnd.adobe.photoshop
      image/vnd.microsoft.icon
    )

Don't know how to require the blob to create a test case, here is a minimal test case:

2.6.1 :005 > io = StringIO.new('test string')
 => #<StringIO:0x00007f8bb4661358> 
2.6.1 :007 > content_type = 'image/bmp'
 => "image/bmp" 
2.6.1 :008 > as2 = ActiveStorage::Blob.create_after_upload! io: io, filename: 'test.txt', content_type: content_type, metadata: nil
  Disk Storage (1.1ms) Uploaded file to key: tug5y2JoVraQYrNCpTLHpoab (checksum: b421md6Yb6t6IWJbeRZYnA==)
   (0.1ms)  begin transaction
  ActiveStorage::Blob Create (0.4ms)  INSERT INTO "active_storage_blobs" ("key", "filename", "content_type", "metadata", "byte_size", "checksum", "created_at") VALUES (?, ?, ?, ?, ?, ?, ?)  [["key", "tug5y2JoVraQYrNCpTLHpoab"], ["filename", "test.txt"], ["content_type", "image/bmp"], ["metadata", "{\"identified\":true}"], ["byte_size", 11], ["checksum", "b421md6Yb6t6IWJbeRZYnA=="], ["created_at", "2019-04-12 18:26:15.738431"]]
   (0.6ms)  commit transaction
 => #<ActiveStorage::Blob id: 2, key: "tug5y2JoVraQYrNCpTLHpoab", filename: "test.txt", content_type: "image/bmp", metadata: {"identified"=>true}, byte_size: 11, checksum: "b421md6Yb6t6IWJbeRZYnA==", created_at: "2019-04-12 18:26:15"> 
2.6.1 :009 > as2.variant(resize: "100x100")
Traceback (most recent call last):
        1: from (irb):9
ActiveStorage::InvariableError (ActiveStorage::InvariableError)
2.6.1 :010 > Rails.version
 => "5.2.3" 

Ideally, Rails should throw an exception if bmp images are not supported.