[boost] mapped_file_source::is_open() is broken under windows Ticket #1232

From: Steven Burns (royalstream_at_[hidden])
Date: 2007-09-05 16:37:18

From: http://svn.boost.org:80/trac/boost/ticket/1232

Under windows, mapped_file_impl::handle_ gets set to INVALID_HANDLE_VALUE 
when the file gets closed or on error.

But mapped_file_source::is_open() incorrectly assumes that if the handle is 
invalid it will have a value of zero and it doesn't consider 
INVALID_HANDLE_VALUE a possibility.

Obviously, adding INVALID_HANDLE_VALUE to mapped_file_source::is_open() 
would be poor design. A better way would be to explose a 
mapped_file_impl::is_valid() method that works as it should depending on the 
platform and have mapped_file_source::is_open() call it.

Regards,

Steven Burns