safe_puts to avoid EPIPE [hashicorpGH-819]

CHANGELOG.md

@@ -8,6 +8,7 @@
     setting. [GH-808]
   - `vagrant ssh` now works on Solaris, where `IdentitiesOnly` was not
     an available option. [GH-820]
+  - Output works properly in the face of broken pipes. [GH-819]
 
 ## 1.0.1 (March 11, 2012)
 

lib/vagrant/command/base.rb

@@ -1,12 +1,16 @@
 require 'log4r'
 
+require "vagrant/util/safe_puts"
+
 module Vagrant
   module Command
     # Base class for any CLI commands.
     #
     # This class provides documentation on the interface as well as helper
     # functions that a command has.
     class Base
+      include Util::SafePuts
+
       def initialize(argv, env)
         @argv = argv
         @env  = env
@@ -41,7 +45,7 @@ def parse_options(opts=nil)
 
         # Add the help option, which must be on every command.
         opts.on_tail("-h", "--help", "Print this help") do
-          puts opts.help
+          safe_puts(opts.help)
           return nil
         end
 

lib/vagrant/command/gem.rb

@@ -1,9 +1,13 @@
 require "rubygems"
 require "rubygems/gem_runner"
 
+require "vagrant/util/safe_puts"
+
 module Vagrant
   module Command
     class Gem < Base
+      include Util::SafePuts
+
       def execute
         # Bundler sets up its own custom gem load paths such that our
         # own gems are never loaded. Therefore, give an error if a user
@@ -20,7 +24,7 @@ def execute
         if @argv.empty? || @argv.include?("-h") || @argv.include?("--help")
           @env.ui.info(I18n.t("vagrant.commands.gem.help_preamble"),
                        :prefix => false)
-          puts
+          safe_puts
         end
 
         # We just proxy the arguments onto a real RubyGems command

lib/vagrant/command/ssh_config.rb

@@ -1,8 +1,12 @@
 require 'optparse'
 
+require "vagrant/util/safe_puts"
+
 module Vagrant
   module Command
     class SSHConfig < Base
+      include Util::SafePuts
+
       def execute
         options = {}
 
@@ -36,7 +40,7 @@ def execute
 
           # Render the template and output directly to STDOUT
           template = "commands/ssh_config/config"
-          $stdout.puts(Util::TemplateRenderer.render(template, variables))
+          safe_puts(Util::TemplateRenderer.render(template, variables))
         end
       end
     end

lib/vagrant/ui.rb

@@ -1,5 +1,7 @@
 require "log4r"
 
+require "vagrant/util/safe_puts"
+
 module Vagrant
   module UI
     # Vagrant UIs handle communication with the outside world (typically
@@ -43,6 +45,8 @@ def ask(*args)
     # This is a UI implementation that outputs the text as is. It
     # doesn't add any color.
     class Basic < Interface
+      include Util::SafePuts
+
       # Use some light meta-programming to create the various methods to
       # output text to the UI. These all delegate the real functionality
       # to `say`.
@@ -112,7 +116,8 @@ def say(type, message, opts=nil)
         channel = type == :error || opts[:channel] == :error ? $stderr : $stdout
 
         # Output!
-        channel.send(printer, format_message(type, message, opts))
+        safe_puts(format_message(type, message, opts),
+                  :io => channel, :printer => printer)
       end
 
       # This is called by `say` to format the message for output.

lib/vagrant/util/safe_puts.rb

@@ -0,0 +1,31 @@
+module Vagrant
+  module Util
+    # This module provides a `safe_puts` method which outputs to
+    # the given IO object, and rescues any broken pipe errors and
+    # ignores them. This is useful in cases where you're outputting
+    # to stdout, for example, and the stdout is closed, but you want to
+    # keep running.
+    module SafePuts
+      # Uses `puts` on the given IO object and safely ignores any
+      # Errno::EPIPE.
+      #
+      # @param [String] message Message to output.
+      # @param [Hash] opts Options hash.
+      def safe_puts(message=nil, opts=nil)
+        message ||= ""
+        opts = {
+          :io => $stdout,
+          :printer => :puts
+        }.merge(opts || {})
+
+        begin
+          opts[:io].send(opts[:printer], message)
+        rescue Errno::EPIPE
+          # This is what makes this a `safe` puts.
+          return
+        end
+      end
+    end
+  end
+end
+