fasmg as preprocessor

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emil

Joined: 16 Dec 2003
Posts: 76
Location: egypt

emil 22 Feb 2017, 17:22

ok , i got it.

22 Feb 2017, 17:22

emil

Joined: 16 Dec 2003
Posts: 76
Location: egypt

emil 24 Feb 2017, 10:02

Hi all ,

may any one explain the next macro , i have tried to got it but .....

Code:

macro x86.parse_operand_value ns,op    
        local buffer,is_name,auto_extrn   
        define buffer op:    
        while 1    
                match sym tail, buffer    
                        define buffer tail    
                        load is_name:1 from Name_XLAT:`sym and 0FFh    
                        if is_name   
                                if defined auto_extrn.sym & (auto_extrn.sym | ~ defined sym)  
                                        extrn sym   
                                        auto_extrn.sym := 1  
                                else if ~ defined sym   
                                        auto_extrn.sym := 0  
                                end if   
                        end if    
                else    
                        break    
                end match    
        end while    
        x86.parse_operand_value ns,op    
end macro

So
1- what this line means

Code:

       define buffer op:

2- what is the "sym" here and where it declared

Code:

     match sym tail, buffer  

     load is_name:1 from Name_XLAT:`sym and 0FFh

3- also if each lined commented so that i can got it.

excuse my newbee.

thanks for any help.

24 Feb 2017, 10:02

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20409
Location: In your JS exploiting you and your system

revolution 24 Feb 2017, 10:15

1 > "buffer" is defined as "op" with a colon (:) appended.

2 > match will define "sym" as the first symbol from "buffer", and "tail" as the all of the remaining symbols from "buffer"

3 > Not sure what you question is here?

24 Feb 2017, 10:15

emil

Joined: 16 Dec 2003
Posts: 76
Location: egypt

emil 24 Feb 2017, 10:43

thanks you

may you kindly explain each line in the macro !!

24 Feb 2017, 10:43

Tomasz Grysztar

Joined: 16 Jun 2003
Posts: 8356
Location: Kraków, Poland

Tomasz Grysztar 24 Feb 2017, 17:01

As I mentioned earlier, this macro is especially tricky. I'd suggest you first take some time to get accustomed with the simpler ones, including the operation of MATCH. You can start with reading the section on MATCH in the manual and then the increasingly complex examples in my introduction to fasmg.

24 Feb 2017, 17:01

emil

Joined: 16 Dec 2003
Posts: 76
Location: egypt

emil 26 Feb 2017, 05:51

any way i have deleted my last two posts ,

thank you all for your help.

26 Feb 2017, 05:51

ProMiNick

Joined: 24 Mar 2012
Posts: 802
Location: Russian Federation, Sochi

ProMiNick 26 Jun 2017, 14:32

Quote:

Code:

...
preprocess

macro invoke name,args&
        iterate arg,args
                indx %%-%+1
                push arg
        end iterate
        call [name]
end macro

invoke  MessageBoxA,0,_message,_caption,0

The output looks like:

Code:

push 0
push _caption
push _message
push 0
call [MessageBoxA]

Is there any way to catch this lines in macro to output:

Code:

invoke  MessageBoxA,0,_message,_caption,0
;iterate arg,0,_message,_caption,0 ;this
;indx 4-1+1 ;and this
push 0
;end iterate ;and this
;indx 4-2+1 ;and this
push _caption
;end iterate ;and this
... ; ...

I mean how to catch them not in time of macro definition but in time params go throw macro?

I tryed to play

Code:

macro preprocess
        local Preprocessor
        macro gate list&
                iterate instr, list
                        macro Preprocessor.instr?! args&
                          ;db `instr `args
                                esc instr args
                        end macro

                end iterate



        end macro 
        gate end,macro,iterate,indx,irp,irpv,repeat,rept,while,break,if,else,match,rmatch,rawmatch,include,postpone,namespace,display
        macro make_interceptor instr
                struc (label) ? decl&
                        instr `label,' ',`decl,13,10
                end struc
        end macro 
        make_interceptor db;display
        namespace Preprocessor

        postpone
                end namespace 
        end postpone
end macro

preprocess;launch CMD line '"%SystemRoot%\system32\notepad.exe" "%OUTPUT%"'

macro ?! args&
  line `args,args
  args
end macro



macro invoke name,args&
        iterate arg,args 
                indx %%-%+1 
                push arg 
        end iterate 
        call [name] 
end macro

invoke  MessageBoxA,0,_message,_caption,0

and output

Code:

line '',
line '',
line '',
line 'macro invoke name,args&',macro invoke name,args&
line '',
line 'invoke MessageBoxA,0,_message,_caption,0',invoke MessageBoxA,0,_message,_caption,0
line 'iterate arg,args',iterate arg,0,_message,_caption,0
line 'indx %%-%+1',indx 4-1+1
line 'push arg',push 0
push 0
line 'end iterate',end iterate
line 'indx %%-%+1',indx 4-2+1
line 'push arg',push _caption
push _caption
line 'end iterate',end iterate
line 'indx %%-%+1',indx 4-3+1
line 'push arg',push _message
push _message
line 'end iterate',end iterate
line 'indx %%-%+1',indx 4-4+1
line 'push arg',push 0
push 0
line 'end iterate',end iterate
line 'call [name]',call [MessageBoxA]
call [MessageBoxA]
line 'end macro',end macro
line 'end namespace',end namespace
line 'end postpone',end postpone

insted of word "line" I wished ";" and instead of blank lines skip them

26 Jun 2017, 14:32

Tomasz Grysztar

Joined: 16 Jun 2003
Posts: 8356
Location: Kraków, Poland

Tomasz Grysztar 29 Jun 2017, 14:51

ProMiNick wrote:

I mean how to catch them not in time of macro definition but in time params go throw macro?

You'd need to modify the way in which macros are defined. Possible, but not easy.

29 Jun 2017, 14:51

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