From: Heesob Park <phasis@...>
Date: 2010-07-27T12:26:16+09:00
Subject: Re: Help: How to pass a struct as a pointer to Win32API?

Hi,

2010/7/27 Jing Li <thyrlian@gmail.com>:
>  Hi all,
>
> As titled, I want to read text content from a standard syslistview32 control
> in an application.  And the syslistview32 control is not a pop-up but
> embedded in the application, which means the control has same process ID as
> the application.  In that case, I don't have to call VirtualAllocEx or
> WriteProcessMemory.
>
> So far, I could successfully get syslistview32 control's handle, count how
> many items listed.  But still can not read its content.  Could you please
> tell me how to do it correctly?
>
> require 'Win32API'
> findwin = Win32API.new('user32', 'FindWindow', 'PP', 'L')
> getdlg = Win32API.new('user32', 'GetDlgItem', 'LL', 'L')
> sendmsg = Win32API.new('user32', 'SendMessage', 'LLLP', 'L')
>
> #Some irrelevant details are ignored
> #Here I've already got syslistview32 control's handle, let's assume it is
> resultslist = 3739380
>
> puts "Count of items = #{sendmsg.call(resultslist, 4100, 0, nil)}"
> #LVM_GETITEMCOUNT = 0x1004
> puts header = getdlg.call(resultslist, 0).to_s(16).upcase
> #No problem, this works
>
> #From here I tried to SendMessage with LVM_GETITEMTEXT parameter to get
> syslistview32's content
> #Solution I: define a struct as described in MSDN, but something wrong when
> I tried to pack, this is due to my lack of knowledge on pack&unpack
> LV_item = Struct.new(:mask, :iItem, :iSubItem, :state, :stateMask, :pszText,
> :cchTextMax, :iImage, :lParam)
> lv_item = LV_item.new()
> puts sendmsg.call(resultslist, 4165, 1, lv_item.to_a.pack("p"))
>    => return value is 1, success?
> puts lv_item.inspect
>    => #<struct LV_item mask=nil, iItem=nil, iSubItem=nil, state=nil,
> stateMask=nil, pszText=nil, cchTextMax=nil, iImage=nil, lParam=nil>
> absolutely not succeed
> #If I initiate lv_item = LV_item.new(0, 0, 0, 0, 0, "", 0, 0, ""), then
> error occurs at packing: can't convert Fixnum into String (TypeError).  Can
> I pack integer pointer except pack("p")?
>
> #Solution II: Directly pack an array and pass to SendMessage, return value
> is still nil
> lv_item = [0, 0, 0, 0, 0, "\000", 0, 0, "\000"]
> lv_item = lv_item.pack("IiiIIpiip")
> puts sendmsg.call(resultslist, 4165, 1, lv_item)
>    => return value is 1, success?
> lv_item = lv_item.unpack("IiiIIpiip")
> puts lv_item.inspect
>    => [0, 0, 0, 0, 0, "\000", 0, 0, "\000"], nothing is padded actually
>
> I really appreciate if you can answer my question, thanks in advance.
>
Here is a code using VirtualAllocEx and WriteProcessMemory for a
general purpose.


require 'Win32API'

findwin = Win32API.new('user32', 'FindWindow', 'PP', 'L')
getdlg = Win32API.new('user32', 'GetDlgItem', 'LL', 'L')
sendmsg = Win32API.new('user32', 'SendMessage', 'LLLP', 'L')

getWindowThreadProcessId = Win32API.new('user32',
'GetWindowThreadProcessId', 'LP', 'L')
openProcess = Win32API.new('kernel32', 'OpenProcess', 'LIL', 'L')
virtualAllocEx = Win32API.new('kernel32', 'VirtualAllocEx', 'LPLLL', 'L')
virtualFreeEx = Win32API.new('kernel32', 'VirtualFreeEx', 'LLLL', 'L')
writeProcessMemory = Win32API.new('kernel32', 'WriteProcessMemory',
'LLPLP', 'I')
readProcessMemory = Win32API.new('kernel32', 'ReadProcessMemory', 'LLPLP', 'I')

PROCESS_VM_OPERATION = 0x08
PROCESS_VM_READ = 0x10
PROCESS_VM_WRITE = 0x20
PROCESS_QUERY_INFORMATION = 0x400
MEM_COMMIT = 0x1000
MEM_RELEASE = 0x8000
PAGE_READWRITE = 0x04
LVM_GETITEMTEXT = 0x1000+45
LVM_GETITEMCOUNT = 0x1000+4
SIZE_OF_LVITEM = 60

resultslist = 0xB0044   ##<== start with some given handle

count = sendmsg.call(resultslist,LVM_GETITEMCOUNT, 0, nil)
lv_item = [0, 0, 0, 0, 0, nil, 512, 0, 0,0,0,0,0,0,0]
lv_item = lv_item.pack("LiiLLpiiLiiLLLL")
pid = 0.chr*4
getWindowThreadProcessId.call(resultslist, pid)
pid = pid.unpack('L').first
process = openProcess.call(PROCESS_VM_OPERATION|PROCESS_VM_READ|PROCESS_VM_WRITE|PROCESS_QUERY_INFORMATION,0,pid)
_lvi=virtualAllocEx.call(process, nil, SIZE_OF_LVITEM,MEM_COMMIT,
PAGE_READWRITE)
_item=virtualAllocEx.call(process, nil, 512, MEM_COMMIT,PAGE_READWRITE)
_subitem=virtualAllocEx.call(process, nil, 512, MEM_COMMIT,PAGE_READWRITE)

for i in 0..count
  lv_item[8,4] = [0].pack('L')
  item = 0.chr * 512
  lv_item[20,4] = [_item].pack('L')
  writeProcessMemory.call(process, _lvi, lv_item, SIZE_OF_LVITEM, nil)
  sendmsg.call(resultslist, LVM_GETITEMTEXT, i, _lvi)

  subitem = 0.chr * 512
  lv_item[8,4] = [1].pack('L')
  lv_item[20,4] = [_subitem].pack('L')
  writeProcessMemory.call(process, _lvi, lv_item, SIZE_OF_LVITEM, nil)
  sendmsg.call(resultslist, LVM_GETITEMTEXT, i, _lvi)

  readProcessMemory.call(process, _item, item, 512, nil)
  readProcessMemory.call(process, _item, subitem, 512, nil)
  item = item.strip!
  subitem = subitem.strip!
  puts "#{item} - #{subitem}"
end

virtualFreeEx.call(process, _lvi, 0, MEM_RELEASE)
virtualFreeEx.call(process, _item, 0, MEM_RELEASE)
virtualFreeEx.call(process, _subitem, 0, MEM_RELEASE)



Regards,
Park Heesob