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require "bindata/base_primitive"
module BinData
# A BinData::Stringz object is a container for a zero ("\0") terminated
# string.
#
# For convenience, the zero terminator is not necessary when setting the
# value. Likewise, the returned value will not be zero terminated.
#
# require 'bindata'
#
# data = "abcd\x00efgh"
#
# obj = BinData::Stringz.new
# obj.read(data)
# obj.snapshot #=> "abcd"
# obj.num_bytes #=> 5
# obj.to_binary_s #=> "abcd\000"
#
# == Parameters
#
# Stringz objects accept all the params that BinData::BasePrimitive
# does, as well as the following:
#
# <tt>:max_length</tt>:: The maximum length of the string including the zero
# byte.
class Stringz < BinData::BasePrimitive
optional_parameters :max_length
def assign(val)
super(binary_string(val))
end
def snapshot
# override to always remove trailing zero bytes
result = super
trim_and_zero_terminate(result).chomp("\0")
end
#---------------
private
def value_to_binary_string(val)
trim_and_zero_terminate(val)
end
def read_and_return_value(io)
max_length = eval_parameter(:max_length)
str = ""
i = 0
ch = nil
# read until zero byte or we have read in the max number of bytes
while ch != "\0" && i != max_length
ch = io.readbytes(1)
str += ch
i += 1
end
trim_and_zero_terminate(str)
end
def sensible_default
""
end
def trim_and_zero_terminate(str)
result = binary_string(str)
truncate_after_first_zero_byte!(result)
trim_to!(result, eval_parameter(:max_length))
append_zero_byte_if_needed!(result)
result
end
def truncate_after_first_zero_byte!(str)
str.sub!(/([^\0]*\0).*/, '\1')
end
def trim_to!(str, max_length = nil)
if max_length
max_length = 1 if max_length < 1
str.slice!(max_length..-1)
if str.length == max_length && str[-1, 1] != "\0"
str[-1, 1] = "\0"
end
end
end
def append_zero_byte_if_needed!(str)
if str.length == 0 || str[-1, 1] != "\0"
str << "\0"
end
end
end
end
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