metasploit-framework/lib/bit-struct/char-field.rb

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# -*- coding: binary -*-
class BitStruct
# Class for fixed length binary strings of characters.
# Declared with BitStruct.char.
class CharField < Field
#def self.default
# don't define this, since it must specify N nulls and we don't know N
#end
# Used in describe.
def self.class_name
@class_name ||= "char"
end
def add_accessors_to(cl, attr = name) # :nodoc:
unless offset % 8 == 0
raise ArgumentError,
"Bad offset, #{offset}, for #{self.class} #{name}." +
" Must be multiple of 8."
end
unless length % 8 == 0
raise ArgumentError,
"Bad length, #{length}, for #{self.class} #{name}." +
" Must be multiple of 8."
end
offset_byte = offset / 8
length_byte = length / 8
last_byte = offset_byte + length_byte - 1
byte_range = offset_byte..last_byte
val_byte_range = 0..length_byte-1
cl.class_eval do
define_method attr do ||
self[byte_range].to_s
end
define_method "#{attr}=" do |val|
val = val.to_s
if val.length < length_byte
val += "\0" * (length_byte - val.length)
end
self[byte_range] = val[val_byte_range]
end
end
end
end
end