By default, you can't use io::file_reader on Windows where the file has byte 26 in the file because it is not opened in binary mode. It sees 26 and assumes EOF (or ctrl-Z or something). I noticed mk_file_writer uses O_BINARY as a flag on Windows. Can the io::file_reader function be changed to use binary mode? (I think this is just changing "r" to "rb" in the fopen flags).

Ref: http://cygwin.com/faq-nochunks.html#faq.api.cr-lf (as linked to from the mingw FAQ about O_BINARY here: http://www.mingw.org/wiki/FAQ)