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using ShellExecute to start msinfo32

Started by Shintaro, April 29, 2014, 08:34:15 PM

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Shintaro

Hi,

Using:
WinAsm 5.1.8.0
Created a Dialog project.

OS: Windows 8.1 64bit

Included Shell32.inc and Shell32.lib

I am trying to get ShellExecute to start msinfo32.

invoke ShellExecute,0,"open", "msinfo32",NULL,NULL,SW_SHOW

I would have thought that would have started msinfo32. But I get a compiler error on the above line:

C:\Temp\Assembly\Projects\test.asm(22) : error A2084: constant value too large
C:\Temp\Assembly\Projects\test.asm(22) : error A2114: INVOKE argument type mismatch : argument : 3

I'm not trying to do anything special, just trying to learn how to use the api correctly.

Any help would be greatly appreciated.
"Wyrd bið ful āræd. Fate is inexorable."

jj2007

You need a chr$ macro:

invoke ShellExecute,0, chr$("open"), chr$("msinfo32"), ...

Or use addr txOpen, addr txInfo ...

Vortex

Hi aparsons,

Jochen is right. You need to use the chr$ macro. You can also try the code below :

include     \masm32\include\masm32rt.inc

.data

operation   db 'open',0
file        db 'msinfo32',0

.code

start:

    invoke ShellExecute,0,ADDR operation,ADDR file,NULL,NULL,SW_SHOW

    invoke ExitProcess,0

END start


Shintaro

Thanks guys,

I appreciate your replies.

Just a couple of quick questions:
What types is the api call expecting, by default? Because I am trying to pass a string and maybe it is expecting an Int?

Is this defined anywhere? Because the MS API just say's, from my limited understanding, that how I used that API, it should have worked.

Cheers.
"Wyrd bið ful āræd. Fate is inexorable."

dedndave

it wants the address of a null-terminated string, which is a dword

    .DATA

szString db 'String',0


to get the address, use the ADDR or OFFSET operator
in this case, i prefer OFFSET

    INVOKE  StdOut,offset szString

Shintaro

Thanks dedndave,

I have spent too much time in other languages. It never occurred to me about a null terminated string.

Thanks again.

Vortex,

I had a look at masm32rt.inc, nice!
At this stage I just want stuff to work so masm32rt makes it easy for me.

Cheers.
"Wyrd bið ful āræd. Fate is inexorable."

dedndave

now that you see how it works, you can use the chr$ macro
it defines the string in the .DATA section and exits with the offset   :biggrin:
the downside is that you can only get the offset one time

Shintaro

Thanks for your reply dedndave,

Are you able to provide a bit of code as an example?
"Wyrd bið ful āræd. Fate is inexorable."

dedndave

first, you can view the chr$() macro to see what it does
from \masm32\macros\macros.asm...
      chr$ MACRO any_text:VARARG
        LOCAL txtname
        .data
          IFDEF __UNICODE__
            WSTR txtname,any_text
            align 4
            .code
            EXITM <OFFSET txtname>
          ENDIF

          txtname db any_text,0
          align 4
          .code
          EXITM <OFFSET txtname>
      ENDM

it switches to the .DATA section, assigns the data, then returns with the offset
i think it was Jochen that mentioned it earlier in this thread
but, here is one way to use it
    INVOKE  MessageBox,0,chr$("Message"),chr$("Title"),MB_OK
here's another
    mov     edx,chr$("String")    ;EDX = address of "String",0
and another
    print   chr$("Hello World"),13,10
that one demonstrates that a "VARARG" can be a number of items

zedd151

I would simply use the 'fn' macro:


fn ShellExecute,0,"open", "msinfo32",NULL,NULL,SW_SHOW


;)

The fn macro takes care of alloting the data, and zero terminating the strings.