From: Ben Nagy <ben@...>
Date: 2006-06-11T12:17:04+09:00
Subject: Re: Getting a list of Processes

> -----Original Message-----
> From: Daniel Berger [mailto:djberg96@gmail.com] 
> Sent: Sunday, June 11, 2006 5:26 AM
> To: ruby-talk ML
> Subject: Re: Getting a list of Processes
> 
> ReggW wrote:
> > Daniel Berger wrote:
> >> ReggW wrote:
> >>> How do you get a list of running Processes using Ruby?
> >>>
> >>> P.S. I'm on Windows
> >>>
> >>> Thanks
> >>>
> >> require 'sys/proctable'
> >> include Sys
> >>
> >> ProcTable.ps{ |proc_struct|
> >>     p proc_struct
[...]

I don't know what you're trying to do, but here's some hackjob code to do it
using Win32API. The basic method is to create a Toolhelp32 snapshot and then
enumerate the processes using Process32First and Process32Next.

---
require 'Win32API'

# some constants
TH32CS_SNAPPROCESS=0x00000002
Proc32Size=(9*4)+260 # 9 DWORDS plus a string of length MAX_PATH (default
260)

class ProcessEntry32
	attr_reader :size, :usage, :pid, :default_heap, :module_id,
:threads, :parent_pid, :base_priority, :flags, :name
	def initialize( raw_entry )
		@size=raw_entry[0..3].unpack('I').first
		@usage=raw_entry[4..7].unpack('I').first #MDSN: always zero
		@pid=raw_entry[8..11].unpack('I').first
		@default_heap=raw_entry[12..15].unpack('I').first # MSDN:
always zero
		@module_id=raw_entry[16..19].unpack('I').first # MSDN:
always zero
		@threads=raw_entry[20..23].unpack('I').first
		@parent_pid=raw_entry[24..27].unpack('I').first
		@base_priority=raw_entry[28..31].unpack('I').first
		@flags=raw_entry[32..35].unpack('I').first # MSDN: always
zero
		@name=raw_entry[36..@size-1].split("\0").first
	end
end

CreateToolhelp32Snapshot=Win32API.new("kernel32","CreateToolhelp32Snapshot",
'LL','L')
Process32First=Win32API.new("kernel32","Process32First",'LP','L')
Process32Next=Win32API.new("kernel32","Process32Next",'LP','L')

snaphandle=CreateToolhelp32Snapshot.Call(TH32CS_SNAPPROCESS,0)
procentryraw="\0"*Proc32Size
procentryraw[0..3]=int2raw(Proc32Size) # need to initialise size or
Process32First will fail
# int2raw is a little helper function I wrote when first learning,
# to convert an int into a DWORD. The core is:
# ("%.8x"%unsigned_int).scan(/../).reverse.map {|b| b.hex}.pack('cccc')
# but there is bound to be a nicer way to do it, so don't copy it. ;)

processes=[]
if Process32First.Call(snaphandle,procentryraw)
	processes.push(ProcessEntry32.new(procentryraw))
else
	fail "horribly"
end
while Process32Next.call(snaphandle,procentryraw) == 1
	processes.push(ProcessEntry32.new(procentryraw))
end

processes.sort {|x,y| x.parent_pid <=> y.parent_pid}.each do |process|
[do stuff]
---

I'm sure that more experienced rubyists can correct my idiomatic usage.
Win32API is scarcely documented, so maybe this will come in handy for
someone at some point.

Cheers,

ben