discourse/lib/theme_store/zip_exporter.rb
Sam cedcdb0057
FEATURE: allow for local theme js assets (#16374)
Due to default CSP web workers instantiated from CDN based assets are still
treated as "same-origin" meaning that we had no way of safely instansiating
a web worker from a theme.

This limits the theme system and adds the arbitrary restriction that WASM
based components can not be safely used.

To resolve this limitation all js assets in about.json are also cached on
local domain.

{
  "name": "Header Icons",
  "assets" : {
    "worker" : "assets/worker.js"
  }
}

This can then be referenced in JS via:

settings.theme_uploads_local.worker

local_js_assets are unconditionally served from the site directly and
bypass the entire CDN, using the pre-existing JavascriptCache

Previous to this change this code was completely dormant on sites which
used s3 based uploads, this reuses the very well tested and cached asset
system on s3 based sites.

Note, when creating local_js_assets it is highly recommended to keep the
assets lean and keep all the heavy working in CDN based assets. For example
wasm files can still live on the CDN but the lean worker that loads it can
live on local.

This change unlocks wasm in theme components, so wasm is now also allowed
in `theme_authorized_extensions`

* more usages of upload.content

* add a specific test for upload.content

* Adjust logic to ensure that after upgrades we still get a cached local js
on save
2022-04-07 07:58:10 +10:00

79 lines
2.1 KiB
Ruby

# frozen_string_literal: true
require_dependency 'compression/zip'
module ThemeStore; end
class ThemeStore::ZipExporter
def initialize(theme)
@theme = theme
@temp_folder = "#{Pathname.new(Dir.tmpdir).realpath}/discourse_theme_#{SecureRandom.hex}"
@export_name = @theme.name.downcase.gsub(/[^0-9a-z.\-]/, '-')
@export_name = "discourse-#{@export_name}" unless @export_name.starts_with?("discourse")
end
def export_name
@export_name
end
def package_filename
export_package
end
def cleanup!
FileUtils.rm_rf(@temp_folder)
end
def with_export_dir(**kwargs)
export_to_folder(**kwargs)
yield File.join(@temp_folder, @export_name)
ensure
cleanup!
end
private
def export_to_folder(extra_scss_only: false)
destination_folder = File.join(@temp_folder, @export_name)
FileUtils.mkdir_p(destination_folder)
@theme.theme_fields.each do |field|
next if extra_scss_only && !field.extra_scss_field?
next unless path = field.file_path
# Belt and braces approach here. All the user input should already be
# sanitized, but check for attempts to leave the temp directory anyway
pathname = Pathname.new(File.join(destination_folder, path))
folder_path = pathname.parent.cleanpath
raise RuntimeError.new("Theme exporter tried to leave directory") unless folder_path.to_s.starts_with?(destination_folder)
pathname.parent.mkpath
path = pathname.realdirpath
raise RuntimeError.new("Theme exporter tried to leave directory") unless path.to_s.starts_with?(destination_folder)
if ThemeField.types[field.type_id] == :theme_upload_var
content = field.upload.content
else
content = field.value
end
File.write(path, content)
end
if !extra_scss_only
File.write(
File.join(destination_folder, "about.json"),
JSON.pretty_generate(@theme.generate_metadata_hash)
)
end
@temp_folder
end
def export_package
export_to_folder
Compression::Zip.new.compress(@temp_folder, @export_name)
end
end