Take a look at that gem!

Attempting to upload an image to the refinerycms system yielded a stack trace returned to the user. In this case, refinery's images_controller is picking up an error in dragonfly.

When we try to upload an image in refinery, we get

	dragonfly (0.8.5) lib/dragonfly/analysis/file_command_analyser.rb:16:in `popen'
	dragonfly (0.8.5) lib/dragonfly/analysis/file_command_analyser.rb:16:in `mime_type'
	dragonfly (0.8.5) lib/dragonfly/function_manager.rb:37:in `call'
	dragonfly (0.8.5) lib/dragonfly/function_manager.rb:37:in `call_last'
	dragonfly (0.8.5) lib/dragonfly/function_manager.rb:36:in `catch'
	dragonfly (0.8.5) lib/dragonfly/function_manager.rb:36:in `call_last'
	dragonfly (0.8.5) lib/dragonfly/function_manager.rb:35:in `each'
	dragonfly (0.8.5) lib/dragonfly/function_manager.rb:35:in `call_last'
	dragonfly (0.8.5) lib/dragonfly/analyser.rb:26:in `analyse'
	dragonfly (0.8.5) lib/dragonfly/job.rb:200:in `analyse'
	(eval):3:in `mime_type'
	dragonfly (0.8.5) lib/dragonfly/active_model_extensions/attachment.rb:152:in `send'
	dragonfly (0.8.5) lib/dragonfly/active_model_extensions/attachment.rb:152:in `set_magic_attributes'
	dragonfly (0.8.5) lib/dragonfly/active_model_extensions/attachment.rb:152:in `each'
	dragonfly (0.8.5) lib/dragonfly/active_model_extensions/attachment.rb:152:in `set_magic_attributes'
	dragonfly (0.8.5) lib/dragonfly/active_model_extensions/attachment.rb:33:in `assign'
	dragonfly (0.8.5) lib/dragonfly/active_model_extensions/class_methods.rb:22:in `image='
	activerecord (3.0.7) lib/active_record/base.rb:1559:in `send'
	activerecord (3.0.7) lib/active_record/base.rb:1559:in `attributes='
	activerecord (3.0.7) lib/active_record/base.rb:1555:in `each'
	activerecord (3.0.7) lib/active_record/base.rb:1555:in `attributes='
	activerecord (3.0.7) lib/active_record/base.rb:1407:in `initialize'
	activerecord (3.0.7) lib/active_record/base.rb:497:in `new'
	activerecord (3.0.7) lib/active_record/base.rb:497:in `create'
	refinerycms-images (0.9.9.21) app/controllers/admin/images_controller.rb:48:in `create'

view raw stack_trace hosted with ❤ by GitHub

Let's check out the top file

	module Dragonfly
	module Analysis
	class FileCommandAnalyser
	include Configurable
	configurable_attr :file_command, "file"
	configurable_attr :use_filesystem, false
	configurable_attr :num_bytes_to_check, 255
	def mime_type(temp_object)
	content_type = if use_filesystem
	`#{file_command} -b --mime '#{temp_object.path}'`
	else
	IO.popen("#{file_command} -b --mime -", 'r+') do |io|
	if num_bytes_to_check
	io.write temp_object.data[0, num_bytes_to_check]
	else
	io.write temp_object.data
	end
	io.close_write
	io.read
	end
	end.split(';').first
	content_type.strip if content_type
	end
	end
	end
	end

view raw file_command_analyser.rb hosted with ❤ by GitHub

So it appears that the error has to do with the IO.popen. Since we know we wouldn't need that call if "use_filesystem" were true, and since line 9 suggests there is a configuration directive for this setting somewhere. We should try to find it.

So we go down the stack trace to the last known point the execution was in another gem. It turns out to be images_controller in the refinerycms gem.

Knowing the name of the controller , I tried some bash-fu and was presently suprised when it worked!

	root@tara:~/tmp/1008583# locate images_controller.rb
	/usr/lib/ruby/gems/1.8/gems/refinerycms-images-0.9.9.21/app/controllers/admin/images_controller.rb
	root@tara:~/tmp/1008583# vim `locate images_controller.rb`

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None the less. There did not appear to be any configuration in that file. I went to the refinery gem root's directory and did a "grep -R dragonfly ." to flesh out any config files. I noticed "lib/refinerycms-images.rb."

	# grep -R Dragonfly .
	./lib/refinerycms-images.rb: app_images = Dragonfly[:images]
	./lib/refinerycms-images.rb: app_images.analyser.register(Dragonfly::Analysis::ImageMagickAnalyser)
	./lib/refinerycms-images.rb: app_images.analyser.register(Dragonfly::Analysis::FileCommandAnalyser)
	./lib/refinerycms-images.rb: app.config.middleware.insert_after 'Rack::Lock', 'Dragonfly::Middleware', :images, '/system/images'
	./lib/refinerycms-images.rb: app.config.middleware.insert_before 'Dragonfly::Middleware', 'Rack::Cache', {
	./config/routes.rb: match '/system/images/*dragonfly', :to => Dragonfly[:images]
	./app/controllers/admin/images_controller.rb: rescue Dragonfly::FunctionManager::UnableToHandle

view raw commands1 hosted with ❤ by GitHub

We check out the file and see the Dragonfly app initialization at line 22. We google around for the Dragonfly docs looking for a reference to where exactly the "use_filesystem" configuration directive must be set. Our search lands us on docs for Dragonfly::Analysis::FileCommandAnalyser

An example for the config is referenced which includes the directive we are looking for.

	app.analyser.register(Dragonfly::Analysis::FileCommandAnalyser) do |a|
	a.use_filesystem = false # defaults to true
	a.file_command = '/opt/local/bin/file' # defaults to 'file'
	a.num_bytes_to_check = 1024 # defaults to 255 - only applies if not using the filesystem
	end

view raw dragonfly_example hosted with ❤ by GitHub

We then modify the source of lib-refinerycms.rb to include the modifications to the analyzer config.

	git diff refinerycms-images.rb
	diff --git a/refinerycms-images.rb b/refinerycms-images.rb
	index 3fef0f7..e3d3caa 100644
	--- a/refinerycms-images.rb
	+++ b/refinerycms-images.rb
	@@ -31,7 +31,9 @@ module Refinery
	app_images.define_macro(ActiveRecord::Base, :image_accessor)
	app_images.analyser.register(Dragonfly::Analysis::ImageMagickAnalyser)
	- app_images.analyser.register(Dragonfly::Analysis::FileCommandAnalyser)
	+ app_images.analyser.register(Dragonfly::Analysis::FileCommandAnalyser) do |a|
	+ a.use_filesystem = true
	+ end
	# This url_suffix makes it so that dragonfly urls work in traditional
	# situations where the filename and extension are required,

view raw refinery_change hosted with ❤ by GitHub

We attempt the image upload again and the upload succeeds. Now, how do I get involved in the refinerycms repo to discuss the changes with the leads? Something like this? https://github.com/resolve/refinerycms/pull/738

Right?