This simple program will ask you if you want to close your actual session. You can say cancel or ok with the corresponding actions after that (not log out, log out). Remember i'm just learning by now. I did a lot of comments and the structure i made it like that for clarity, of course it's not the most optimizing code posible.
.386
.model flat,stdcall
option casemap:none
include \masm32\include\windows.inc
include \masm32\include\user32.inc
include \masm32\include\kernel32.inc
includelib \masm32\lib\user32.lib
includelib \masm32\lib\kernel32.lib
.data
titl byte 'System message',0 ; Three message boxes in total (with the same title).
content1 byte 'Log out now?',0
content2 byte 'Windows will close your session now.',0
content3 byte 'Your actual session will continue now.',0
.data?
indicator dword ? ; To indicate if a condition (ok button was pushed) occurs.
value_retorn dword ? ; For store the button pushed in the message box (for later compare).
.code
main proc
mov indicator,0 ; Begins as zero (i should done this in the .data).
call send_messag1 ; Creates the first message box.
call compare ; Compares which button was pushed.
cmp indicator,0 ; Ok button will move 1 to indicator.
je not_logoff ; But if is zero user has pushed cancel. So let's jump.
push EWX_LOGOFF ; Ok button pushed, so logout now.
call ExitWindowsEx
not_logoff:
call ExitProcess ; And we finish here.
main endp
send_messag1 proc ; Makes the first message box.
push MB_OKCANCEL
lea ebx,titl
push ebx
lea ebx,content1
push ebx
push 0
call MessageBox
mov value_retorn,eax ; We store here the button pushed.
ret
send_messag1 endp
compare proc ; Compares which button was pushed and sets indicator
mov eax,value_retorn ; as 1 if ok button was pushed or continues in zero otherwise.
cmp eax,IDOK
jne dont_close ; No ok button pushed, so we jump.
call final_messag ; Ok button pushed, so we show the according message box.
mov indicator,1 ; Here we say ok button was pushed.
jmp end_
dont_close:
call messag_continu ; Show other message box.
end_:
ret
compare endp
final_messag proc ; Message box saying goodbye...
push MB_OK
lea ebx,titl
push ebx
lea ebx,content2
push ebx
push 0
call MessageBox
ret
final_messag endp
messag_continu proc ; Message box saying go on...
push MB_OK
lea ebx,titl
push ebx
lea ebx,content3
push ebx
push 0
call MessageBox
ret
messag_continu endp
end main
Works fine here on my Win10 64. Had a look at the code and its clean, tidy and very clear, just the way it should be.
> call ExitProcess
Slightly unorthodox: You might consider using the invoke macro.
Probably better with,
push 0 ; should have the extra arg
call ExitProcess
Quote from: felipe on May 11, 2017, 01:32:35 PM
This simple program will ask you if you want to close your actual session. You can say cancel or ok with
Something I would change is:
replace:
lea ebx,titl
push ebx
with
push offset titl
And more 4 or 5 instances of the same or similar.
You also forgot all required parameters a couple of times, namely with ExitWindowsEx and ExitProcess, so is better to use INVOKE which will help you account for that.
I understand that offset would generate less code (smaller). I like to use call. I will check the requirements for the ExitProcess function because i hasn't done it. But for the ExitWindowsEx i'm sure that's the only parameter to pass.
Quote from: felipe on May 12, 2017, 10:56:51 AM
But for the ExitWindowsEx i'm sure that's the only parameter to pass.
If you are sure Microsoft will need to review the documentation, my friend.
Quote from: aw27 on May 12, 2017, 12:01:42 AMYou also forgot all required parameters a couple of times, namely with ExitWindowsEx and ExitProcess, so is better to use INVOKE
Quote from: hutch-- on July 22, 2016, 12:00:01 AMSuch are the slings and arrows of outrageous fortune when you actually cannot rely on anyone holding you hot little hand and have to write low level assembler. :P
;)
Quote from: aw27 on May 12, 2017, 01:34:07 PM
Quote from: felipe on May 12, 2017, 10:56:51 AM
But for the ExitWindowsEx i'm sure that's the only parameter to pass.
If you are sure Microsoft will need to review the documentation, my friend.
I don't get it. This is from the win32.hlp for the api documentation:
"The ExitWindowsEx function either logs off, shuts down, or shuts down and restarts the system.
BOOL ExitWindowsEx(
UINT uFlags, // shutdown operation
DWORD dwReserved // reserved
);"
And nothing more my friend... :icon_eek:
Then:
"dwReserved
Reserved; this parameter is ignored. "
Maybe you think it's for shutdown the system. I have used the function just for logoff.
Quote
"The ExitWindowsEx function either logs off, shuts down, or shuts down and restarts the system.
BOOL ExitWindowsEx(
UINT uFlags, // shutdown operation
DWORD dwReserved // reserved
);"
And nothing more my friend... :icon_eek:
My friend, you are using documentation from last century, probably applying in full to Windows 95.
Also.. reserved never meant optional you must indeed put something there. And strangely enough, optional does not mean not required in ASM, you must also put something there. Confused?
include \Masm32\MasmBasic\Res\JBasic.inc ; ## console demo, builds in 32- or 64-bit mode with ML, AsmC, JWasm, HJWasm ##
Init ; OPT_64 1 ; put 0 for 32 bit, 1 for 64 bit assembly
PrintLine Chr$("This code was assembled with ", @AsmUsed$(1), " in ", jbit$, "-bit format")
MsgBox 0, "Wow, it works!!!!", "Hi", MB_OK or MB_SETFOREGROUND
jinvoke ExitProcess, 0 ; we exit here, no need to shut down
jinvoke ExitWindowsEx, EWX_POWEROFF, SHTDN_REASON_MAJOR_APPLICATION
EndOfCode
It's a 64-bit source, but it requires only MasmBasic (http://masm32.com/board/index.php?topic=94.0) and nothing else. To build the project, open it in RichMasm and hit F6.
Then try to remove or comment out the SHTDN_ parameter, and hit F6 again to build it. Or add one more parameter, whatever you like. Example:
jinvoke ExitWindowsEx, EWX_POWEROFF ; , SHTDN_REASON_MAJOR_APPLICATION
Result:
\Masm32\MasmBasic\Res\JBasic.inc(6) : Error A2114: forced error: ## not enough arguments for ExitWindowsEx ##
There is a REASON why Microsoft, 20 years ago, invented the invoke macro. The reason is that even the best programmers are really bad at counting their own fingers. CreateWindowEx, for example, needs eleven (!) arguments, and if you are bad at counting, it might even work but you introduce a bug that will be exceptionally difficult to chase. Most probably it will pop up on your client's site, five years later, and while you are still proud that you are able to pass all these arguments with push eax like a real assembly programmer, you have absolutely no clue why your beautiful application crashes in Windows 15. And your client is really furious :icon_mrgreen:
Quote from: jj2007 on May 12, 2017, 06:27:01 PM
jinvoke ExitProcess, 0 ; we exit here, no need to shut down
jinvoke ExitWindowsEx, EWX_POWEROFF, SHTDN_REASON_MAJOR_APPLICATION
A bit scaring but jinvoke works like a charm :bgrin:
so this: "dwReserved
Reserved; this parameter is ignored. "
It's just for high level languages?
And, well i think one should keep looking for the O.S documentation, specially if there are errors. So, no, i'm not confused at all, my friend...
Quote from: felipe on May 12, 2017, 11:16:50 PM
i'm not confused at all, my friend...
:icon_confused:
Quote from: felipe on May 12, 2017, 11:16:50 PM
so this: "dwReserved
Reserved; this parameter is ignored. "
It's just for high level languages?
Just an incomplete documentation, normally reserved should be zero.
In Windows 2000 it was ignored, but after that, in WindowsXP it was documented and used.
BOOL ExitWindows(
DWORD dwReserved, // reserved; must be zero
UINT uReserved // reserved; must be zero
);EDIT: https://msdn.microsoft.com/en-us/library/windows/desktop/aa376868(v=vs.85).aspx
Ok, so where do you recommend a good documentation (updated) for the api functions?
Quote from: felipe on May 12, 2017, 11:57:03 PM
Ok, so where do you recommend a good documentation (updated) for the api functions?
The latest is online, simply search for the function name.
For offline, the latest is the MSDN Library for Visual Studio 2008 SP1
Ok, thanks a lot. :icon14:
felipe,
Windows API functions are a bit "all over the place" and not necessarily consistent but one thing you must do to write reliable code is get the argument count right. When you get a function that has a "Reserved" status, you set it to zero. You can in fact write your own functions the same way, an empty argument can be used like a LOCAL variable in the called function, not my own style but it works OK and it seems Windows has done this on enough occasions.
Quote from: hutch-- on May 13, 2017, 02:40:15 AMan empty argument can be used like a LOCAL variable in the called function
Interesting idea. 5 bytes shorter in the proc, 2 bytes more for every invoke though 8)