Segmentation fault while using Ruby::DL

Ruby
1

Hello.

I tried to call a simple method on Windows (XP, Win7 - didn’t matter)
machine and it seems that i will get a segmentation fault depending of
the Ruby version. Any ideas why that might happen?

Here is the offending code (doc for EnumWindows is at
EnumWindows function (winuser.h) - Win32 apps | Microsoft Learn):

require ‘dl/import’

module Testing

extend DL::Importable

dlload “user32.dll”

USER32 = DL.dlopen(“user32”)
EnumWindows = USER32[‘EnumWindows’, ‘IPL’]

CALLBACK = DL.callback(‘ILL’) do |curr_hwnd, p|
p curr_hwnd
0
end

module_function

def enumerate
EnumWindows.call(CALLBACK, 0)
end
end

Testing.enumerate

And when trying to run it with different Ruby 1.8.6 patchlevels, i see
the following output:

S:>ruby -v
ruby 1.8.6 (2007-09-24 patchlevel 111) [i386-mswin32]

S:>testing.rb
328312

S:>ruby -v
ruby 1.8.6 (2010-02-04 patchlevel 398) [i386-mingw32]

S:>testing.rb
393884
S:/testing.rb:20: [BUG] Segmentation fault
ruby 1.8.6 (2010-02-04) [i386-mingw32]

This application has requested the Runtime to terminate it in an unusual
way.
Please contact the application’s support team for more information.

So, p398 gives me a segfault. On the other hand FFI example at
http://wiki.github.com/ffi/ffi/windows-examples works perfectly.

Does that mean that I have to convert one old Ruby lib to use FFI
altogether? Or even if it doesn’t mean that, then would you recommend me
to do it?

Jarmo

2

Just wanted to let you know that segfault doesn’t happen with win32-api
also.

Jarmo

3

So, p398 gives me a segfault. On the other hand FFI example at
http://wiki.github.com/ffi/ffi/windows-examples works perfectly.

It’s probably a bug. You can report it at redmine.ruby-lang.org

Does that mean that I have to convert one old Ruby lib to use FFI
altogether? Or even if it doesn’t mean that, then would you recommend me
to do it?

I’d recommend using FFI only. Plus you get cross VM coolness points.
-rp

4

Roger P. wrote:

So, p398 gives me a segfault. On the other hand FFI example at
http://wiki.github.com/ffi/ffi/windows-examples works perfectly.

It’s probably a bug. You can report it at redmine.ruby-lang.org

Does that mean that I have to convert one old Ruby lib to use FFI
altogether? Or even if it doesn’t mean that, then would you recommend me
to do it?

I’d recommend using FFI only. Plus you get cross VM coolness points.
-rp

Does your recommendation also apply when the library in question is
Windows only?

Jarmo

5

I’d recommend using FFI only. Plus you get cross VM coolness points.
-rp

Does your recommendation also apply when the library in question is
Windows only?

I’m not actually totally into the subject (I’ve done a few ffi
examples), but I’ve heard that ffi is cleaner than DL, so…a weak
recommendation for “always” from me, it appears.
-rp