exiting programs directly, without PostQuitMessage ?

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Slai

Joined: 11 Jan 2006
Posts: 40
Location: NY/Bulgaria

Slai 01 Sep 2006, 10:59

Is it ok if I dont restore the previous condition of the stack pointer when I exit the program ? I tryed using directly ExitProcess instead of PostQuitMessage without poping ebx esi edi and it worked, so I guess Windows restores esp anyways? What are the risks if I exit this way?

Code:

include '%include%/win32a.inc'
;        invoke  GetModuleHandle,0
        invoke  DialogBoxParam,eax,0,HWND_DESKTOP,DialogProc,0

proc DialogProc uses ebx esi edi ,hwnd,msg,wparam,lparam
        cmp     [msg],WM_CLOSE 
        je      close
        xor     eax,eax 
        ret
 close: invoke  ExitProcess,0
endp

data resource ;section '.rsrc' resource data readable
    directory RT_DIALOG,dialog0
        resource dialog0,0,LANG_ENGLISH+SUBLANG_DEFAULT,demonstration
    dialog demonstration,'Create message box',0,0,400,300,WS_VISIBLE+WS_SYSMENU+WS_MAXIMIZEBOX+WS_MINIMIZEBOX+WS_THICKFRAME+DS_CENTER,2
    enddialog
end data
data import ;section '.import' import data readable writeable
  library kernel32,'KERNEL32.DLL', user32,'USER32.DLL'
  include '%apia%\kernel32.inc'
  include '%apia%\user32.inc'
end data

01 Sep 2006, 10:59

shoorick

Joined: 25 Feb 2005
Posts: 1614
Location: Ukraine

shoorick 01 Sep 2006, 11:14

correct way to close dialog box is using of EndDialog, and ExitProcess has to be placed after DialogBoxParam. otherwise everything depends on capabilities of OS to clear all resources by process. some controls may allocate memory or other resources, and should be closed correctly to release all of them - this will be done by default dialog procedure. You may feel visually ok just because your program is extremelly lite, but this way is incorrect.

01 Sep 2006, 11:14

shoorick

Joined: 25 Feb 2005
Posts: 1614
Location: Ukraine

shoorick 01 Sep 2006, 11:16

btw, is it working example with commented GetModuleHandle? Wink

01 Sep 2006, 11:16

Slai

Joined: 11 Jan 2006
Posts: 40
Location: NY/Bulgaria

Slai 01 Sep 2006, 17:21

Yes it works without it. There was a thread in here that was discussing the use of GetModuleHandle, and I didn't saw an satisfying aswer why it should be used, but I guess it should be used for compability isues ..
I know about the correct way to close a dialog, I was just curious how incorect is this one. So exiting this way may leave resources in the memory and make this memory unusable by the other programs ?

01 Sep 2006, 17:21

shoorick

Joined: 25 Feb 2005
Posts: 1614
Location: Ukraine

shoorick 04 Sep 2006, 05:13

So exiting this way may leave resources in the memory and make this memory unusable by the other programs > yes

04 Sep 2006, 05:13

f0dder

Joined: 19 Feb 2004
Posts: 3175
Location: Denmark

f0dder 04 Sep 2006, 11:12

shoorick wrote:

So exiting this way may leave resources in the memory and make this memory unusable by the other programs > yes

Nope. Windows does cleanup when your process terminates. The only thing you have to be vary of is GDI stuff if you want to support win9x - win9x is a leaky piece of shit that doesn't handle stuff well.

_________________
carpe noctem

04 Sep 2006, 11:12

Slai

Joined: 11 Jan 2006
Posts: 40
Location: NY/Bulgaria

Slai 05 Sep 2006, 01:45

I goth both, expected and satisfying answers Smile

. Thank you. I guess it's best if I dont use this direct exiting, for any case :], and because I have some GDI stuff for changing the font colour.

05 Sep 2006, 01:45

shoorick

Joined: 25 Feb 2005
Posts: 1614
Location: Ukraine

shoorick 05 Sep 2006, 04:54

Windows does cleanup when your process terminates
i will not insist on opposite, but there are could be controls on dialog which may create some global/shareable/COM etc. objects which can be left after process has been terminated. editbox, btw, allocates memory in global memory (to be compatible with win3x i think, unless it has DS_LOCALEDIT style).

05 Sep 2006, 04:54

f0dder

Joined: 19 Feb 2004
Posts: 3175
Location: Denmark

f0dder 05 Sep 2006, 06:01

"There is no such thing as global memory on win32", especially not NT. Closest you come would be named memory mapped files, but those should be cleaned up even on TerminateProcess. And ExitProcess is even cleaner than that.

Or perhaps you know something I don't Smile

05 Sep 2006, 06:01

shoorick

Joined: 25 Feb 2005
Posts: 1614
Location: Ukraine

shoorick 05 Sep 2006, 06:54

Or perhaps you know something I don't > i do not think so Very Happy

just prefer to be sure then hope. btw, it is possible exit window proc with "retn" instead "retn 16" (whole byte economy Smile

), but i do not think somebody does like this Wink

05 Sep 2006, 06:54

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