Setting $? manually - possible?

ruby-talk
1

Hi all,

Ruby 1.8.4

I'm working on a custom Process.waitpid method (for Windows). It works fine, except that I want to be able to set the Process::Status ($?) manually within the method. Specifically, the exitstatus and pid. This is pure Ruby, btw.

The problem is that Process::Status.new has been undef'd within process.c and $? has been set to readonly.

I've tinkered with redefining Process::Status.new, a custom Process::Status#initialize, instance_variable_set, etc - all to no avail.

Is there any way to set $? from within Ruby?

Thanks,

Dan

2

Hi,

From: Daniel Berger <djberg96@gmail.com>
Reply-To: ruby-talk@ruby-lang.org
To: ruby-talk@ruby-lang.org (ruby-talk ML)
Subject: Setting $? manually - possible?
Date: Sat, 29 Apr 2006 23:41:19 +0900

Hi all,

Ruby 1.8.4

I'm working on a custom Process.waitpid method (for Windows). It works fine, except that I want to be able to set the Process::Status ($?) manually within the method. Specifically, the exitstatus and pid. This is pure Ruby, btw.

The problem is that Process::Status.new has been undef'd within process.c and $? has been set to readonly.

I've tinkered with redefining Process::Status.new, a custom Process::Status#initialize, instance_variable_set, etc - all to no avail.

Is there any way to set $? from within Ruby?

Something like this is possible but not recommended.

require 'Win32API'

FIXNUM_FLAG = 0x01
rb_int2inum = Win32API.new('msvcrt-ruby18','rb_int2inum','L','L') # long -> VALUE
rb_iv_set = Win32API.new('msvcrt-ruby18', 'rb_iv_set', 'LPL', 'V')

    system("ver")
p $? # -> #<Process::Status: pid=920,exited(0)>
    obj = rb_int2inum.call($?.object_id) ^ FIXNUM_FLAG
    rb_iv_set.call(obj,"pid",rb_int2inum.call(1))
    rb_iv_set.call(obj,"status",rb_int2inum.call(0xFF00))
p $? # -> #<Process::Status: pid=1,exited(255)>

Regards,
Park Heesob

3

Park Heesob wrote:

Hi,

From: Daniel Berger <djberg96@gmail.com>
Reply-To: ruby-talk@ruby-lang.org
To: ruby-talk@ruby-lang.org (ruby-talk ML)
Subject: Setting $? manually - possible?
Date: Sat, 29 Apr 2006 23:41:19 +0900

Hi all,

Ruby 1.8.4

I'm working on a custom Process.waitpid method (for Windows). It works fine, except that I want to be able to set the Process::Status ($?) manually within the method. Specifically, the exitstatus and pid. This is pure Ruby, btw.

The problem is that Process::Status.new has been undef'd within process.c and $? has been set to readonly.

I've tinkered with redefining Process::Status.new, a custom Process::Status#initialize, instance_variable_set, etc - all to no avail.

Is there any way to set $? from within Ruby?

Something like this is possible but not recommended.

require 'Win32API'

FIXNUM_FLAG = 0x01
rb_int2inum = Win32API.new('msvcrt-ruby18','rb_int2inum','L','L') # long -> VALUE
rb_iv_set = Win32API.new('msvcrt-ruby18', 'rb_iv_set', 'LPL', 'V')

   system("ver")
p $? # -> #<Process::Status: pid=920,exited(0)>
   obj = rb_int2inum.call($?.object_id) ^ FIXNUM_FLAG
   rb_iv_set.call(obj,"pid",rb_int2inum.call(1))
   rb_iv_set.call(obj,"status",rb_int2inum.call(0xFF00))
p $? # -> #<Process::Status: pid=1,exited(255)>

Heh, that's awesome. I may just add that, though I'll toss in some error checking and extra documentation. :slight_smile:

Thanks,

Dan