[BUG]bug in "IF.inc"?

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alorent

Joined: 05 Dec 2005
Posts: 221

alorent 09 Feb 2010, 12:47

Hello guys,

Please, look at this code:

Code:



include 'win32ax.inc' 
include 'macro\if.inc'

.data

p1 db 0

.code

  start:

       lea     eax, [p1]         ; [eax] = 0

   .if ~(byte [eax])

               db 0cch

 .endif


      .if ~byte [eax]

         db 0cch

 .endif


      invoke  MessageBox,HWND_DESKTOP,"Hi! I'm the example program!",invoke GetCommandLine,MB_OK
       invoke  ExitProcess,0

.end start

The second ".if" is processed correctly so, the "db 0cch" is *executed*.

But the first ".if" does *not* execute the "db 0cch"!!!

So, it seems that the parenthesis are messing all out?

Thanks!

09 Feb 2010, 12:47

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20335
Location: In your JS exploiting you and your system

revolution 09 Feb 2010, 12:52

Compiles to:

Code:

00402006    8038 00         cmp     byte[eax],0
00402009    74 01           jz      0x0040200c
0040200b    cc              int3
0040200c    8038 00         cmp     byte[eax],0
0040200f    75 01           jnz     0x00402012
00402011    cc              int3

Bug confirmed.

09 Feb 2010, 12:52

alorent

Joined: 05 Dec 2005
Posts: 221

alorent 09 Feb 2010, 21:38

Thanks revolution for confirming the bug.

Is the bug related to the "IF.INC" file or a fasm bug?

Thanks!

09 Feb 2010, 21:38

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20335
Location: In your JS exploiting you and your system

revolution 10 Feb 2010, 01:35

This is related to the 'if.inc' macro file. Not to the fasm core assembler. But still definitely needs fixing.

10 Feb 2010, 01:35

baldr

Joined: 19 Mar 2008
Posts: 1651

baldr 10 Feb 2010, 08:58

alorent,

You're right, this bug is related to parentheses handling in PARSECOND macro. Negation was added twice, before and after opening parenthesis. This should fix it:

Code:

      match (,symb                      ; 134
      \\\{                              ; 135
          parsed equ parsed neg@cond,<  ; 136
          define neg@cond               ; ADDED
          define nest@cond +            ; 137
          define symb@cond              ; 138
      \\\}                              ; 139

10 Feb 2010, 08:58

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20335
Location: In your JS exploiting you and your system

revolution 10 Feb 2010, 09:03

With baldr's fix: now compiles to:

Code:

00402006    8038 00         cmp     byte[eax],0
00402009    75 01           jnz     0x0040200c
0040200b    cc              int3
0040200c    8038 00         cmp     byte[eax],0
0040200f    75 01           jnz     0x00402012
00402011    cc              int3

Fix confirmed.

10 Feb 2010, 09:03

alorent

Joined: 05 Dec 2005
Posts: 221

alorent 10 Feb 2010, 11:13

Thanks baldr!!!

Great work!!! Very Happy

10 Feb 2010, 11:13

Tomasz Grysztar

Joined: 16 Jun 2003
Posts: 8353
Location: Kraków, Poland

Tomasz Grysztar 10 Feb 2010, 16:19

I included the fix in the latest 1.69.12 package.

10 Feb 2010, 16:19

DOS386

Joined: 08 Dec 2006
Posts: 1900

DOS386 14 Feb 2010, 14:22

Tomasz Grysztar wrote:

I included the fix in the latest 1.69.12 package.

COOL

1.69.12 is out and announcement is hidden in the Macroinstructions subforum. Could you please look into this bug for 1.69.13 ?

14 Feb 2010, 14:22

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