metasploit-framework/lib/rex/struct2/s_string.rb

#!/usr/bin/ruby

# Rex::Struct2
module Rex
module Struct2

class SString
	
	require 'rex/struct2/element'
	include Rex::Struct2::Element

	attr_reader  :size, :default, :pad
	attr_writer  :default, :pad

	def initialize(size=nil, default=nil, pad=nil)
		self.size = size
		@default  = default
		@pad      = pad
		reset()
	end

	def size=(newsize)
		if !newsize
			self.restraint = nil
		else
			res = Rex::Struct2::Constant(size)
			self.restraint = Rex::Struct2::Restraint(res, res, true)
		end
	end

	def reset
		self.value = @default
	end

	def to_s
		string = self.value

		return if !string

		# pad if short
		if restraint && restraint.min && self.pad && restraint.min > string.length
			string += self.pad * (restraint.min - string.length)
		end
		# truncate if long
		if restraint && restraint.max
			string = string.slice(0, restraint.max)
		end

		return string
	end

	def from_s(bytes)
		# we don't have enough bytes to satisfy our minimum
		if restraint && restraint.min && bytes.length < restraint.min
			return
		end

		if restraint && restraint.max
			self.value = bytes.slice(0, restraint.max)
		else
			self.value = bytes.dup
		end

		return(self.slength)
	end
end

# end Rex::Struct2
end
end