# TruncatedDataError is raised when IO#readbytes fails to read enough data.
class TruncatedDataError<IOError
def initialize(mesg, data) # :nodoc:
@data = data
super(mesg)
end
# The read portion of an IO#readbytes attempt.
attr_reader :data
end
class IO
# Reads exactly +n+ bytes.
#
# If the data read is nil an EOFError is raised.
#
# If the data read is too short a TruncatedDataError is raised and the read
# data is obtainable via its #data method.
def readbytes(n)
str = read(n)
if str == nil
raise EOFError, "End of file reached"
end
if str.size < n
raise TruncatedDataError.new("data truncated", str)
end
str
end
end
if __FILE__ == $0
begin
loop do
print STDIN.readbytes(6)
end
rescue TruncatedDataError
p $!.data
raise
end
end
|