From: nobu.nokada@...
Date: 2003-11-27T14:10:36+09:00
Subject: Re: [BUG] File#rewind, File#syswrite, File#pos on Cygwin build

Hi,

At Thu, 20 Nov 2003 18:50:20 +0900,
ts wrote:
> R> "Do not mix with other methods that write to ios or you may get
> R> unpredictable results."
> R> http://www.rubycentral.com/book/ref_c_io.html#IO.syswrite
> 
>  No, no.

Robert is correct.

Note that IO#pos is shorthand for seek(0, IO::SEEK_CUR) which
an interface for fseek, that means it is buffered IO routine.
You have to use #sysseek instead.

>    puts "Now at position #{file.pos}"
     puts "Now at position #{file.sysseek(0, IO::SEEK_CUR)}"

> moulon% ruby -v b.rb
> ruby 1.8.0 (2003-08-04) [sparc-solaris2.7]
> Now at position 3330
> Now at position 0
> 46 bytes written
> Now at position 46
> moulon% 
> 
>  the problem is in cygwin and linux ...

This behavior is not guaranteed.  And also, once stdio layer
operation is done, whether sysio works well or not is unknown.

-- 
Nobu Nakada