Remove leopard/tiger checking and just retry exec using safe_exec

lib/vagrant/ssh.rb

@@ -12,6 +12,7 @@ module Vagrant
     autoload :Session, 'vagrant/ssh/session'
 
     include Util::Retryable
+    include Util::SafeExec
 
     # Reference back up to the environment which this SSH object belongs
     # to
@@ -56,10 +57,8 @@ module Vagrant
       # Some hackery going on here. On Mac OS X Leopard (10.5), exec fails
       # (GH-51). As a workaround, we fork and wait. On all other platforms,
       # we simply exec.
-      pid = nil
-      pid = fork if Util::Platform.leopard? || Util::Platform.tiger?
-      Kernel.exec "ssh #{command_options.join(" ")} #{options[:username]}@#{options[:host]}".strip if pid.nil?
-      Process.wait(pid) if pid
+      command = "ssh #{command_options.join(" ")} #{options[:username]}@#{options[:host]}".strip
+      safe_exec(command)
     end
 
     # Opens an SSH connection to this environment's virtual machine and yields

lib/vagrant/util.rb

@@ -8,6 +8,7 @@ module Vagrant
     autoload :Platform,                  'vagrant/util/platform'
     autoload :ResourceLogger,            'vagrant/util/resource_logger'
     autoload :Retryable,                 'vagrant/util/retryable'
+    autoload :SafeExec,                  'vagrant/util/safe_exec'
     autoload :StackedProcRunner,         'vagrant/util/stacked_proc_runner'
     autoload :TemplateRenderer,          'vagrant/util/template_renderer'
   end

lib/vagrant/util/safe_exec.rb

@@ -0,0 +1,28 @@
+module Vagrant
+  module Util
+    # This module provies a `safe_exec` method which is a drop-in
+    # replacement for `Kernel.exec` which addresses a specific issue
+    # which manifests on OS X 10.5 and perhaps other operating systems.
+    # This issue causes `exec` to fail if there is more than one system
+    # thread. In that case, `safe_exec` automatically falls back to
+    # forking.
+    module SafeExec
+      def safe_exec(command)
+        fork_instead = false
+        begin
+          pid = nil
+          pid = fork if fork_instead
+          Kernel.exec(command) if pid.nil?
+          Process.wait(pid) if pid
+        rescue Errno::E045
+          # We retried already, raise the issue and be done
+          raise if fork_instead
+
+          # The error manifested itself, retry with a fork.
+          fork_instead = true
+          retry
+        end
+      end
+    end
+  end
+end

test/vagrant/ssh_test.rb

@@ -20,10 +20,8 @@ class SshTest < Test::Unit::TestCase
       mock_ssh
       @ssh.stubs(:check_key_permissions)
       @ssh.stubs(:port).returns(2222)
-      Kernel.stubs(:exec)
+      @ssh.stubs(:safe_exec)
       Kernel.stubs(:system).returns(true)
-
-      Vagrant::Util::Platform.stubs(:leopard?).returns(false)
     end
 
     should "raise an exception if SSH is not found" do
@@ -41,7 +39,7 @@ class SshTest < Test::Unit::TestCase
     should "check key permissions prior to exec" do
       exec_seq = sequence("exec_seq")
       @ssh.expects(:check_key_permissions).with(@env.config.ssh.private_key_path).once.in_sequence(exec_seq)
-      Kernel.expects(:exec).in_sequence(exec_seq)
+      @ssh.expects(:safe_exec).in_sequence(exec_seq)
       @ssh.connect
     end
 
@@ -81,24 +79,6 @@ class SshTest < Test::Unit::TestCase
       @ssh.connect
     end
 
-    context "on leopard" do
-      setup do
-        Vagrant::Util::Platform.stubs(:leopard?).returns(true)
-      end
-
-      teardown do
-        Vagrant::Util::Platform.stubs(:leopard?).returns(false)
-      end
-
-      should "fork, exec, and wait" do
-        pid = mock("pid")
-        @ssh.expects(:fork).once.returns(pid)
-        Process.expects(:wait).with(pid)
-
-        @ssh.connect
-      end
-    end
-
     context "checking windows" do
       teardown do
         Mario::Platform.forced = Mario::Platform::Linux
@@ -116,7 +96,7 @@ class SshTest < Test::Unit::TestCase
     end
 
     def ssh_exec_expect(port, key_path, uname, host)
-      Kernel.expects(:exec).with() do |arg|
+      @ssh.expects(:safe_exec).with() do |arg|
         assert arg =~ /^ssh/, "ssh command expected"
         assert arg =~ /-p #{port}/, "-p #{port} expected"
         assert arg =~ /-i #{key_path}/, "-i #{key_path} expected"