(#7122) Enforce call arity on actions in the CLI wrapper.

We had a problem, previously, in the generic translation of command line
arguments to Ruby method calls: we could mistake the options, added by the CLI
wrapper, for a positional argument to the action method.

This was caused by a combination of factors, but primarily that the wrapper
methods for actions are designed to present a friendly, helpful Ruby API for
internal use.  Consequently, they have a default value if you don't wish to
pass options.

Unfortunately, this meant that the options that the CLI *always* passed could
be treated as a positional argument instead, and the default set of options
added to the back of the call.

To resolve this we now check the number of positional arguments in the CLI
wrapper, and raise an exception if they are mismatched.  This makes the
generic CLI handling do the right thing in adapting the command line
arguments to the Ruby API.

(As an aside, we would have had a similar-but-different failure mode if we
 type-checked positional arguments: these calls would have failed with an
 invalid argument validation error.)

Reviewed-By: Max Martin <max@puppetlabs.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/lib/puppet/interface/action.rb b/lib/puppet/interface/action.rb
index ac66d2946..9c9741b52 100644
--- a/lib/puppet/interface/action.rb
+++ b/lib/puppet/interface/action.rb
@@ -168,11 +168,12 @@ class Puppet::Interface::Action
   # this stuff work, because it would have been cleaner.  Which gives you an
   # idea how motivated we were to make this cleaner.  Sorry.
   # --daniel 2011-03-31
+  attr_reader :positional_arg_count
   def when_invoked=(block)
 
     internal_name = "#{@name} implementation, required on Ruby 1.8".to_sym
 
-    arity = block.arity
+    arity = @positional_arg_count = block.arity
     if arity == 0 then
       # This will never fire on 1.8.7, which treats no arguments as "*args",
       # but will on 1.9.2, which treats it as "no arguments".  Which bites,