I'm trying to install ruby on QNX 6.2. I get as far as 'make install' 
and then there seems to be a problem with using sysread on a buffered 
stream.

It's easy to reproduce the problem just calling FileUtils#copy_file:

===================================
# cat a
1
2
3
# cat b
# ./ruby -e 'require "./lib/fileutils"; FileUtils.copy_file "a", "b"'
./lib/fileutils.rb:409:in `sysread': sysread for buffered IO (IOError)
         from ./lib/fileutils.rb:409:in `copy_stream'
         from ./lib/fileutils.rb:397:in `copy_file'
         from ./lib/fileutils.rb:396:in `open'
         from ./lib/fileutils.rb:396:in `copy_file'
         from ./lib/fileutils.rb:395:in `open'
         from ./lib/fileutils.rb:395:in `copy_file'
         from -e:1
===================================

I had the same problem when building 1.7.3, except of course that was 
using ftools.rb and File.syscopy.

The prebuilt binary (1.6.7) from the QNX repository does not have this 
problem.