FileSystem driver has new allow_relative_home param

If set to true, then `home` can be a relative path (relative to current working dir).

Relative path needed for convenience in dummy test app test setup. Added new param to make it opt-in, to make sure it's completely backwards compat and does not introduce any potential security issues -- you need to opt in to new supported behavior with new allow_relative_home param.

.rubocop.yml

@@ -10,6 +10,12 @@ AllCops:
     - 'spec/dummy_test_app/**/*'
     - 'bin/rails'
 
+Style/GuardClause:
+  Enabled: false
+
+StyleI/IfUnlessModifier:
+  Enabled: false
+
 Bundler/DuplicatedGem:
   Exclude:
     - 'Gemfile'

lib/browse_everything/driver/file_system.rb

@@ -9,13 +9,17 @@ def icon
 
       def validate_config
         raise BrowseEverything::InitializationError, 'FileSystem driver requires a :home argument' if config[:home].blank?
+
+        unless config[:home].start_with?("/") || config[:allow_relative_home] == true
+          raise BrowseEverything::InitializationError, 'FileSystem driver :home argument must be absolute unless :allow_relative_home is set'
+        end
       end
 
       # Retrieve the contents of a directory
       # @param path [String] the path to a file system resource
       # @return [Array<BrowseEverything::FileEntry>]
       def contents(path = '')
-        real_path = File.join(config[:home], path)
+        real_path = File.join(home_path, path)
         values = if File.directory?(real_path)
                    make_directory_entry real_path
                  else
@@ -55,6 +59,15 @@ def details(path, display = File.basename(path))
 
       private
 
+      def home_path
+        @home_path ||= if config[:allow_relative_home] == true
+                         # expand relative to current working directory
+                         File.expand_path(config[:home])
+                       else
+                         config[:home]
+                       end
+      end
+
       # Construct an array of FileEntry objects for the contents of a
       # directory
       # @param real_path [String] path to the file system directory
@@ -65,7 +78,7 @@ def make_directory_entry(real_path)
       end
 
       def make_pathname(path)
-        Pathname.new(File.expand_path(path)).relative_path_from(Pathname.new(config[:home]))
+        Pathname.new(File.expand_path(path)).relative_path_from(Pathname.new(home_path))
       end
 
       def file_size(path)

spec/dummy_test_app/config/browse_everything_providers.yml

@@ -3,7 +3,8 @@
 # The file_system provider can be a path to any directory on the server where your application is running.
 #
 file_system:
-  home: /Users/jrochkind/code/browse-everything/.internal_test_app
+  allow_relative_home: true
+  home: ./
 # dropbox:
 #   client_id: YOUR_DROPBOX_APP_KEY
 #   client_secret: YOUR_DROPBOX_APP_SECRET