symbol 'sprintf' out of scope

Index > Windows > symbol 'sprintf' out of scope

Author

Thread

l4m2

Joined: 15 Jan 2015
Posts: 674

l4m2 16 Oct 2015, 23:24

I was trying to use sprintf in fasm and wrote

Code:

include 'win32ax.inc'
macro japi [name] { if used name
                    label name dword at name
                   end if }

.code

  start:
        invoke  sprintf, ddd, "%d", 3
        invoke  MessageBox,HWND_DESKTOP,ddd,invoke GetCommandLine,MB_OK
        invoke  ExitProcess,0

.end start

section '.data' data readable writeable
     ddd: db 32 dup 0
     ;library mscvrt,'mscvrt.DLL'
import mscvrt,sprintf,'sprintf'
    japi sprintf

and error occured:

symbol 'sprintf' out of scope
label sprintf dword at sprintf[/list]

16 Oct 2015, 23:24

l4m2

Joined: 15 Jan 2015
Posts: 674

l4m2 16 Oct 2015, 23:33

and this one can be successfully compiled but runtime error

Code:

; Simple text editor - fasm example program

format PE GUI 4.0
entry start

include 'win32a.inc'

IDM_NEW   = 101
IDM_EXIT  = 102
IDM_ABOUT = 901

section '.text' code readable executable

  start:
        invoke  sprintf, ddd, "%d", 3
        invoke  MessageBox,HWND_DESKTOP,ddd,"",MB_OK
        invoke  ExitProcess,0


section '.data' data readable writeable

   ddd db 32 dup 0

section '.idata' import data readable writeable

  library kernel,'KERNEL32.DLL',\
          user,'USER32.DLL',\
          mscvrt,'msvcrt.DLL'

  import kernel,\
         ExitProcess,'ExitProcess'

  import user,\
         MessageBox,'MessageBoxA'

  import mscvrt,sprintf,'sprintf'

16 Oct 2015, 23:33

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20333
Location: In your JS exploiting you and your system

revolution 17 Oct 2015, 00:20

If you want to put string pointers in invoke calls then you need to use win32ax.inc.

And sprintf is a ccall function so you need to use cinvoke.

17 Oct 2015, 00:20

l4m2

Joined: 15 Jan 2015
Posts: 674

l4m2 17 Oct 2015, 02:01

So why does the function 1 complied failed?
cinvoke should be used but here even if you use invoke it runs successfully and just there'd be some rubbish on the stack (but still thank you for your answering about this!)

17 Oct 2015, 02:01

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20333
Location: In your JS exploiting you and your system

revolution 17 Oct 2015, 02:57

There is a difference between a string pointer and a string constant:

Code:

push "AB" ;push 0x00004241 <--- string constant
org 0x12345678
AB: db "AB",0
push AB ;push 0x12345678 <--- pointer to string

The win32ax version of the macros will convert string constants to string pointers for you.

17 Oct 2015, 02:57

< Last Thread | Next Thread >

Forum Rules:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum