Re: Help: How to pass a struct as a pointer to Win32API?

Hi Park,

Thanks for your answer, and I've tried your code, everything is fine but
nothing is retrieved for item or subitem.

So the result will be like this:
 -
 -
 -
which should be "#{item} - #{subitem}"

Could you plz tell me what's wrong?  Meanwhile I will investigate on this.

BTW, does it matter if I remove VirtualAllocEx and WriteProcessMemory part?
Since I mentioned it's not a pop-up.

Thanks a lot.

Regards,
Jing Li


2010/7/27 Heesob Park <[e-mail]>

> Hi,
>
> 2010/7/27 Jing Li <[e-mail]>:
> >  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
>
>