From: Brian Feldman <green@...>
Date: 2004-05-25T11:27:50+09:00
Subject: Re: compiling mmap?

On Tue, May 25, 2004 at 04:04:53AM +0900, Mark Hubbart wrote:
> 
> On May 24, 2004, at 9:43 AM, ts wrote:
> 
> >#!/usr/bin/ruby
> >require 'mmap'
> >m0 = Mmap.new("/tmp/aa", "a")
> >m0 << "abcdef"
> >puts m0
> >File.open("/tmp/bb", "w") {|f| f.puts "aaa" }
> >m1 = Mmap.new("/tmp/bb", "w")
> >m1 << "abcdef"
> >puts m1
> 
> mark@imac% pbpaste | ruby
> #<Mmap:0x27270>
> -:8: [BUG] Bus Error
> ruby 1.9.0 (2004-04-11) [powerpc-darwin]
> 
> zsh: done       pbpaste |
> zsh: abort      ruby
> 
> 
> 
> it looks like the second test...

Looks like Darwin does not automatically translate PROT_WRITE into
PROT_READ | PROT_WRITE.  The concept of write-only memory regions in
userland programs is pretty strange... disassemble the instruction
currently executing and it's probably a RMW instruction.  Allowing
the user to specify PROT_WRITE alone probably shouldn't happen in
Ruby.

-- 
Brian Fundakowski Feldman                           \'[ FreeBSD ]''''''''''\
  <> green@FreeBSD.org                               \  The Power to Serve! \
 Opinions expressed are my own.                       \,,,,,,,,,,,,,,,,,,,,,,\