Updated mcollective.init according to OSCI-658

[packages/precise/mcollective.git] / lib / mcollective / shell.rb

diff --git a/lib/mcollective/shell.rb b/lib/mcollective/shell.rb
new file mode 100644 (file)
index 0000000..257fc4b
--- /dev/null
+++ b/lib/mcollective/shell.rb
@@ -0,0 +1,87 @@
+module MCollective
+  # Wrapper around systemu that handles executing of system commands
+  # in a way that makes stdout, stderr and status available.  Supports
+  # timeouts and sets a default sane environment.
+  #
+  #   s = Shell.new("date", opts)
+  #   s.runcommand
+  #   puts s.stdout
+  #   puts s.stderr
+  #   puts s.status.exitstatus
+  #
+  # Options hash can have:
+  #
+  #   cwd         - the working directory the command will be run from
+  #   stdin       - a string that will be sent to stdin of the program
+  #   stdout      - a variable that will receive stdout, must support <<
+  #   stderr      - a variable that will receive stdin, must support <<
+  #   environment - the shell environment, defaults to include LC_ALL=C
+  #                 set to nil to clear the environment even of LC_ALL
+  #
+  class Shell
+    attr_reader :environment, :command, :status, :stdout, :stderr, :stdin, :cwd
+
+    def initialize(command, options={})
+      @environment = {"LC_ALL" => "C"}
+      @command = command
+      @status = nil
+      @stdout = ""
+      @stderr = ""
+      @stdin = nil
+      @cwd = Dir.tmpdir
+
+      options.each do |opt, val|
+        case opt.to_s
+          when "stdout"
+            raise "stdout should support <<" unless val.respond_to?("<<")
+            @stdout = val
+
+          when "stderr"
+            raise "stderr should support <<" unless val.respond_to?("<<")
+            @stderr = val
+
+          when "stdin"
+            raise "stdin should be a String" unless val.is_a?(String)
+            @stdin = val
+
+          when "cwd"
+            raise "Directory #{val} does not exist" unless File.directory?(val)
+            @cwd = val
+
+          when "environment"
+            if val.nil?
+              @environment = {}
+            else
+              @environment.merge!(val.dup)
+            end
+        end
+      end
+    end
+
+    # Actually does the systemu call passing in the correct environment, stdout and stderr
+    def runcommand
+      opts = {"env"    => @environment,
+              "stdout" => @stdout,
+              "stderr" => @stderr,
+              "cwd"    => @cwd}
+
+      opts["stdin"] = @stdin if @stdin
+
+      # Running waitpid on the cid here will start a thread
+      # with the waitpid in it, this way even if the thread
+      # that started this process gets killed due to agent
+      # timeout or such there will still be a waitpid waiting
+      # for the child to exit and not leave zombies.
+      @status = systemu(@command, opts) do |cid|
+        begin
+          sleep 1
+          Process::waitpid(cid)
+        rescue SystemExit
+        rescue Errno::ECHILD
+        rescue Exception => e
+          Log.info("Unexpected exception received while waiting for child process: #{e.class}: #{e}")
+        end
+      end
+    end
+  end
+end