Print out a tree of ruby exceptions for a given context

ruby_exception_tree.rb

# Generated using this code from http://blog.nicksieger.com/articles/2006/09/06/rubys-exception-hierarchy/
exceptions = []
tree = {}
ObjectSpace.each_object(Class) do |cls|
  next unless cls.ancestors.include? Exception
  next if exceptions.include? cls
  next if cls.superclass == SystemCallError # avoid dumping Errno's
  exceptions << cls
  cls.ancestors.delete_if {|e| [Object, Kernel].include? e }.reverse.inject(tree) {|memo,cls| memo[cls] ||= {}}
end

indent = 0
tree_printer = Proc.new do |t|
  t.keys.sort { |c1,c2| c1.name <=> c2.name }.each do |k|
    space = (' ' * indent); space ||= ''
    puts space + k.to_s
    indent += 2; tree_printer.call t[k]; indent -= 2
  end
end
tree_printer.call tree

#
# Exception tree from MSF when in exploit context (psexec in this case)
#
# BasicObject
#   PP::ObjectMixin
#     ERB::Util
#       PCAPRUB
#         JSON::Ext::Generator::GeneratorMethods::Object
#           SNMP::BER
#             ActiveSupport::Dependencies::Loadable
#               ActiveSupport::Dependencies::Blamable
#                 Exception
#                   StandardError
#                     ArgumentError
#                       Rex::Exception
#                         Msf::Exception
#                           Msf::AuxiliaryError
#                             Msf::MissingActionError
#                           Msf::ExploitError
#                             Msf::IncompatiblePayloadError
#                             Msf::MissingPayloadError
#                             Msf::MissingTargetError
#                           Msf::NoCompatiblePayloadError
#                           Msf::OptionValidateError
#                           Msf::ValidationError
#                     RuntimeError
#                       Rex::Exception
#                         Msf::Exception
#                           Msf::EncodingError
#                             Msf::BadGenerateError
#                             Msf::BadcharError
#                             Msf::NoEncodersSucceededError
#                             Msf::NoKeyError
#                           Msf::NopError
#                             Msf::NoNopsSucceededError
#                           Msf::PluginLoadError
 
# Generated using this code from http://blog.nicksieger.com/articles/2006/09/06/rubys-exception-hierarchy/