From: Alan Davies <NOSPAMcs96and@...>
Date: 2003-11-19T02:12:17+09:00
Subject: [BUG] File#rewind, File#syswrite, File#pos on Cygwin build

On the cygwin build of ruby v1.8.0, I have encountered a strange bug 
when using rewind, syswrite and pos.  If you open a file in read/write 
mode, read the contents, rewind, syswrite some data, then File#pos 
always seems to return zero.  This does not happen if you use the 
windows build, or you replace 'syswrite' with 'write'.

e.g:

$ cat syswrite.rb
#!/bin/ruby

testStr = "hello\nthis is some example text\nblah blah blah"

# read it, rewind, then write it back again
File.open("out.txt", 'r+') do |file|
   file.readlines
   file.rewind
   bytes = file.syswrite(testStr)
   puts "#{bytes} bytes written"
   puts "Now at position #{file.pos}"
end

$ ls > out.txt

$ syswrite.rb
46 bytes written
Now at position 0