Setting $? manually - possible?


#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,

I’m working on a custom Process.waitpid method (for Windows). It works
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 H.


#3

Park H. wrote:

Hi all,

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