Merge branch 'inline-syntax-check'

* fixes https://tickets.opscode.com/browse/CHEF-4986
* Improves syntax check speed for Ruby 1.9+, especially when using bundler.

2 files changed, 107 insertions, 7 deletions

diff --git a/lib/chef/cookbook/syntax_check.rb b/lib/chef/cookbook/syntax_check.rb
index 59888e2ba3..4f8dcff6dc 100644
--- a/lib/chef/cookbook/syntax_check.rb
+++ b/lib/chef/cookbook/syntax_check.rb
@@ -17,6 +17,8 @@
 #
 
 require 'pathname'
+require 'stringio'
+require 'erubis'
 require 'chef/mixin/shell_out'
 require 'chef/mixin/checksum'
 
@@ -161,28 +163,127 @@ class Chef
 
       def validate_template(erb_file)
         Chef::Log.debug("Testing template #{erb_file} for syntax errors...")
-        result = shell_out("erubis -x #{erb_file} | ruby -c")
+        if validate_inline?
+          validate_erb_file_inline(erb_file)
+        else
+          validate_erb_via_subcommand(erb_file)
+        end
+      end
+
+      def validate_ruby_file(ruby_file)
+        Chef::Log.debug("Testing #{ruby_file} for syntax errors...")
+        if validate_inline?
+          validate_ruby_file_inline(ruby_file)
+        else
+          validate_ruby_by_subcommand(ruby_file)
+        end
+      end
+
+      # Whether or not we're running on a version of ruby that can support
+      # inline validation. Inline validation relies on the `RubyVM` features
+      # introduced with ruby 1.9, so 1.8 cannot be supported.
+      def validate_inline?
+        defined?(RubyVM::InstructionSequence)
+      end
+
+      # Validate the ruby code in an erb template. Uses RubyVM to do syntax
+      # checking, so callers should check #validate_inline? before calling.
+      def validate_erb_file_inline(erb_file)
+        old_stderr = $stderr
+
+        engine = Erubis::Eruby.new
+        engine.convert!(IO.read(erb_file))
+
+        ruby_code = engine.src
+
+        # Even when we're compiling the code w/ RubyVM, syntax errors just
+        # print to $stderr. We want to capture this and handle the printing
+        # ourselves, so we must temporarily swap $stderr to capture the output.
+        tmp_stderr = $stderr = StringIO.new
+
+        abs_path = File.expand_path(erb_file)
+        RubyVM::InstructionSequence.new(ruby_code, erb_file, abs_path, 0)
+
+        true
+      rescue SyntaxError
+        $stderr = old_stderr
+        invalid_erb_file(erb_file, tmp_stderr.string)
+        false
+      ensure
+        # be paranoid about setting stderr back to the old value.
+        $stderr = old_stderr if defined?(old_stderr) && old_stderr
+      end
+
+      # Validate the ruby code in an erb template. Pipes the output of `erubis
+      # -x` to `ruby -c`, so it works with any ruby version, but is much slower
+      # than the inline version.
+      # --
+      # TODO: This can be removed when ruby 1.8 support is dropped.
+      def validate_erb_via_subcommand(erb_file)
+        result = shell_out("erubis -x #{erb_file} | #{ruby} -c")
         result.error!
         true
       rescue Mixlib::ShellOut::ShellCommandFailed
+        invalid_erb_file(erb_file, result.stderr)
+        false
+      end
+
+      # Debug a syntax error in a template.
+      def invalid_erb_file(erb_file, error_message)
         file_relative_path = erb_file[/^#{Regexp.escape(cookbook_path+File::Separator)}(.*)/, 1]
         Chef::Log.fatal("Erb template #{file_relative_path} has a syntax error:")
-        result.stderr.each_line { |l| Chef::Log.fatal(l.chomp) }
+        error_message.each_line { |l| Chef::Log.fatal(l.chomp) }
+        nil
+      end
+
+      # Validate the syntax of a ruby file. Uses (Ruby 1.9+ only) RubyVM to
+      # compile the code without evaluating it or spawning a new process.
+      # Callers should check #validate_inline? before calling.
+      def validate_ruby_file_inline(ruby_file)
+        # Even when we're compiling the code w/ RubyVM, syntax errors just
+        # print to $stderr. We want to capture this and handle the printing
+        # ourselves, so we must temporarily swap $stderr to capture the output.
+        old_stderr = $stderr
+        tmp_stderr = $stderr = StringIO.new
+        abs_path = File.expand_path(ruby_file)
+        file_content = IO.read(abs_path)
+        RubyVM::InstructionSequence.new(file_content, ruby_file, abs_path, 0)
+        true
+      rescue SyntaxError
+        $stderr = old_stderr
+        invalid_ruby_file(ruby_file, tmp_stderr.string)
         false
+      ensure
+        # be paranoid about setting stderr back to the old value.
+        $stderr = old_stderr if defined?(old_stderr) && old_stderr
       end
 
-      def validate_ruby_file(ruby_file)
-        Chef::Log.debug("Testing #{ruby_file} for syntax errors...")
-        result = shell_out("ruby -c #{ruby_file}")
+      # Validate the syntax of a ruby file by shelling out to `ruby -c`. Should
+      # work for all ruby versions, but is slower and uses more resources than
+      # the inline strategy.
+      def validate_ruby_by_subcommand(ruby_file)
+        result = shell_out("#{ruby} -c #{ruby_file}")
         result.error!
         true
       rescue Mixlib::ShellOut::ShellCommandFailed
+        invalid_ruby_file(ruby_file, result.stderr)
+        false
+      end
+
+      # Debugs ruby syntax errors by printing the path to the file and any
+      # diagnostic info given in +error_message+
+      def invalid_ruby_file(ruby_file, error_message)
         file_relative_path = ruby_file[/^#{Regexp.escape(cookbook_path+File::Separator)}(.*)/, 1]
         Chef::Log.fatal("Cookbook file #{file_relative_path} has a ruby syntax error:")
-        result.stderr.each_line { |l| Chef::Log.fatal(l.chomp) }
+        error_message.each_line { |l| Chef::Log.fatal(l.chomp) }
         false
       end
 
+      # Returns the full path to the running ruby.
+      def ruby
+        Gem.ruby
+      end
+
     end
   end
 end
diff --git a/spec/unit/cookbook/syntax_check_spec.rb b/spec/unit/cookbook/syntax_check_spec.rb
index 85d6950a45..40a89c99a4 100644
--- a/spec/unit/cookbook/syntax_check_spec.rb
+++ b/spec/unit/cookbook/syntax_check_spec.rb
@@ -28,7 +28,6 @@ describe Chef::Cookbook::SyntaxCheck do
     Chef::Log.logger = Logger.new(StringIO.new)
     Chef::Log.level = :warn # suppress "Syntax OK" messages
 
-
     @attr_files = %w{default.rb smokey.rb}.map { |f| File.join(cookbook_path, 'attributes', f) }
     @defn_files = %w{client.rb server.rb}.map { |f| File.join(cookbook_path, 'definitions', f)}
     @recipes = %w{default.rb gigantor.rb one.rb}.map { |f| File.join(cookbook_path, 'recipes', f) }