hacked in some lamey signedness foo

git-svn-id: file:///home/svn/incoming/trunk@2845 4d416f70-5f16-0410-b530-b9f4589650da

lib/rex/struct2/c_struct.rb

@@ -48,11 +48,12 @@ class CStruct < SStruct
 	attr_reader  :v
 
 	@@dt_table = {
-	  'uint8'     => proc { |*a| Rex::Struct2::Generic.new('C', *a) },
-	  'uint16v'   => proc { |*a| Rex::Struct2::Generic.new('v', *a) },
-	  'uint32v'   => proc { |*a| Rex::Struct2::Generic.new('V', *a) },
-	  'uint16n'   => proc { |*a| Rex::Struct2::Generic.new('n', *a) },
-	  'uint32n'   => proc { |*a| Rex::Struct2::Generic.new('N', *a) },
+	  'uint8'     => proc { |*a| Rex::Struct2::Generic.new('C', false, *a) },
+	  'int16v'    => proc { |*a| Rex::Struct2::Generic.new('v',  true, *a) },
+	  'uint16v'   => proc { |*a| Rex::Struct2::Generic.new('v', false, *a) },
+	  'uint32v'   => proc { |*a| Rex::Struct2::Generic.new('V', false, *a) },
+	  'uint16n'   => proc { |*a| Rex::Struct2::Generic.new('n', false, *a) },
+	  'uint32n'   => proc { |*a| Rex::Struct2::Generic.new('N', false, *a) },
 	  'string'    => proc { |*a| Rex::Struct2::SString.new(*a) },
 	  'sstruct'   => proc { |*a| Rex::Struct2::SStruct.new(*a) },
 	  'object'    => proc { |o| o },

lib/rex/struct2/generic.rb

@@ -12,9 +12,21 @@ class Generic
 	attr_reader  :default
 	attr_writer  :default
 
-	def initialize(packspec, default=nil)
+	attr_accessor :mask, :check_mask
+
+	def initialize(packspec, signed=false, default=nil)
 		@packspec = packspec
 		@default  = default
+
+		bytelen = [ -1 ].pack(@packspec).length
+		self.mask = (1 << (8 * bytelen)) - 1
+
+		if signed
+			self.check_mask = 1 << (8 * bytelen - 1)
+		else
+			self.check_mask = 0
+		end
+
 		reset()
 	end
 
@@ -44,6 +56,11 @@ class Generic
 		return if restraint && restraint.max && len > restraint.max
 		return if restraint && restraint.min && len < restraint.min
 		# else set our value and return length used for this element
+
+		if (value & check_mask) != 0
+			value = -((~value & mask) + 1)
+		end
+
 		self.value = value
 		return(len)
 	end