FIX: always test and coerce to image on upload

In the past the filename of the origin was used as the source
for the extension of the file when optimizing on upload.

We now use the actual calculated extension based on upload data.

lib/upload_creator.rb

@@ -34,7 +34,13 @@ class UploadCreator
     end
 
     DistributedMutex.synchronize("upload_#{user_id}_#{@filename}") do
-      if FileHelper.is_image?(@filename)
+      # test for image regardless of input
+      @image_info = FastImage.new(@file) rescue nil
+
+      is_image = FileHelper.is_image?(@filename)
+      is_image ||= @image_info && FileHelper.is_image?("test.#{@image_info.type}")
+
+      if is_image
         extract_image_info!
         return @upload if @upload.errors.present?
 
@@ -51,6 +57,7 @@ class UploadCreator
           optimize!        if should_optimize?
         end
 
+        # conversion may have switched the type
         image_type = @image_info.type.to_s
       end
 
@@ -69,17 +76,27 @@ class UploadCreator
       # return the previous upload if any
       return @upload unless @upload.nil?
 
+      fixed_original_filename = nil
+      if is_image
+        # we have to correct original filename here, no choice
+        # otherwise validation will fail and we can not save
+        # TODO decide if we only run the validation on the extension
+        if File.extname(@filename) != ".#{image_type}"
+          fixed_original_filename = "#{@filename}.fixed.#{image_type}"
+        end
+      end
+
       # create the upload otherwise
       @upload = Upload.new
       @upload.user_id           = user_id
-      @upload.original_filename = @filename
+      @upload.original_filename = fixed_original_filename || @filename
       @upload.filesize          = filesize
       @upload.sha1              = sha1
       @upload.url               = ""
       @upload.origin            = @opts[:origin][0...1000] if @opts[:origin]
       @upload.extension         = image_type || File.extname(@filename)[1..10]
 
-      if FileHelper.is_image?(@filename)
+      if is_image
         @upload.width, @upload.height = ImageSizer.resize(*@image_info.size)
       end
 
@@ -101,7 +118,7 @@ class UploadCreator
         end
       end
 
-      if @upload.errors.empty? && FileHelper.is_image?(@filename) && @opts[:type] == "avatar"
+      if @upload.errors.empty? && is_image && @opts[:type] == "avatar"
         Jobs.enqueue(:create_avatar_thumbnails, upload_id: @upload.id, user_id: user_id)
       end
 
@@ -141,7 +158,7 @@ class UploadCreator
 
     OptimizedImage.ensure_safe_paths!(from, to)
 
-    from = OptimizedImage.prepend_decoder!(from)
+    from = OptimizedImage.prepend_decoder!(from, nil, filename: "image.#{@image_info.type}")
     to = OptimizedImage.prepend_decoder!(to)
 
     begin
@@ -229,7 +246,7 @@ class UploadCreator
     path = @file.path
 
     OptimizedImage.ensure_safe_paths!(path)
-    path = OptimizedImage.prepend_decoder!(path)
+    path = OptimizedImage.prepend_decoder!(path, nil, filename: "image.#{@image_info.type}")
 
     Discourse::Utils.execute_command('convert', path, '-auto-orient', path)
 
@@ -243,20 +260,22 @@ class UploadCreator
   def crop!
     max_pixel_ratio = Discourse::PIXEL_RATIOS.max
 
+    filename_with_correct_ext = "image.#{@image_info.type}"
+
     case @opts[:type]
     when "avatar"
       width = height = Discourse.avatar_sizes.max
-      OptimizedImage.resize(@file.path, @file.path, width, height, filename: @filename, allow_animation: allow_animation)
+      OptimizedImage.resize(@file.path, @file.path, width, height, filename: filename_with_correct_ext, allow_animation: allow_animation)
     when "profile_background"
       max_width = 850 * max_pixel_ratio
       width, height = ImageSizer.resize(@image_info.size[0], @image_info.size[1], max_width: max_width, max_height: max_width)
-      OptimizedImage.downsize(@file.path, @file.path, "#{width}x#{height}\>", filename: @filename, allow_animation: allow_animation)
+      OptimizedImage.downsize(@file.path, @file.path, "#{width}x#{height}\>", filename: filename_with_correct_ext, allow_animation: allow_animation)
     when "card_background"
       max_width = 590 * max_pixel_ratio
       width, height = ImageSizer.resize(@image_info.size[0], @image_info.size[1], max_width: max_width, max_height: max_width)
-      OptimizedImage.downsize(@file.path, @file.path, "#{width}x#{height}\>", filename: @filename, allow_animation: allow_animation)
+      OptimizedImage.downsize(@file.path, @file.path, "#{width}x#{height}\>", filename: filename_with_correct_ext, allow_animation: allow_animation)
     when "custom_emoji"
-      OptimizedImage.downsize(@file.path, @file.path, "100x100\>", filename: @filename, allow_animation: allow_animation)
+      OptimizedImage.downsize(@file.path, @file.path, "100x100\>", filename: filename_with_correct_ext, allow_animation: allow_animation)
     end
 
     extract_image_info!