1 files changed, 37 insertions, 0 deletions
diff --git a/railties/lib/rails/app_rails_loader.rb b/railties/lib/rails/app_rails_loader.rb
new file mode 100644
index 0000000000..44f4d3dabc
--- /dev/null
+++ b/railties/lib/rails/app_rails_loader.rb
@@ -0,0 +1,37 @@
+require 'pathname'
+
+module Rails
+  module AppRailsLoader
+    RUBY = File.join(*RbConfig::CONFIG.values_at("bindir", "ruby_install_name")) + RbConfig::CONFIG["EXEEXT"]
+    EXECUTABLES = ['bin/rails', 'script/rails']
+
+    def self.exec_app_rails
+      cwd   = Dir.pwd
+
+      exe   = find_executable
+      exe ||= find_executable_in_parent_path
+      return unless exe
+
+      exec RUBY, exe, *ARGV if find_executable
+      Dir.chdir("..") do
+        # Recurse in a chdir block: if the search fails we want to be sure
+        # the application is generated in the original working directory.
+        exec_app_rails unless cwd == Dir.pwd
+      end
+    rescue SystemCallError
+      # could not chdir, no problem just return
+    end
+
+    def self.find_executable
+      EXECUTABLES.find do |exe|
+        File.exists?(exe) && File.read(exe) =~ /(APP|ENGINE)_PATH/
+      end
+    end
+
+    def self.find_executable_in_parent_path(path = Pathname.new(Dir.pwd))
+      EXECUTABLES.find do |exe|
+        File.exists?(File.join(path, exe)) || !path.root? && find_executable_in_parent_path(path.parent)
+      end
+    end
+  end
+end