How to use PUSHD macro to push the offset?

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revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20516
Location: In your JS exploiting you and your system

revolution 06 Nov 2004, 03:03

The PUSHD macro (in WIN32AX.INC) has the following line:

Code:

  else if _ # first in <_addr first,_ADDR first>

And it appears as thought it is meant to allow the pushing of an offset.
So I tried the following:

Code:

 stdcall _foo,eax,19,ecx,addr [esi+_is.bar],addr [esi+_is.tar]

It does not work and I get compile error "error: undefined symbol."

How can I take advantage of the PUSHD macro to push the offsets?

I know I can manually use the following but it is ugly and not clear.

Code:

 lea edx,[esi+_is.tar]
 push edx
 lea edx,[esi+_is.bar]
 stdcall _foo,eax,19,ecx,edx

06 Nov 2004, 03:03

pelaillo
Missing in inaction

Joined: 19 Jun 2003
Posts: 878
Location: Colombia

pelaillo 06 Nov 2004, 15:07

pushd is not a macro, it is an instruction. Afaik, in order to push a non immediate offset (one that cannot be calculated at compile time), you will need lea as you do. The same construct is used by MASM when you use addr, the difference is that eax will be used.

06 Nov 2004, 15:07

Tomasz Grysztar

Joined: 16 Jun 2003
Posts: 8367
Location: Kraków, Poland

Tomasz Grysztar 06 Nov 2004, 16:03

It should be

Code:

stdcall _foo,eax,19,ecx,addr esi+_is.bar,addr esi+_is.tar

06 Nov 2004, 16:03

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20516
Location: In your JS exploiting you and your system

revolution 06 Nov 2004, 16:45

Oh yeah, I can see how it works now.

I had copied the PUSHD macro to my code but omitted to copy the line "addr equ".

The error I got was actually "addr symbol undefined", but I did not know because the error does not explicitly say which symbol was undefined.

Actually, since it came up, is it possible to get the error function in FASM to print which symbol it cannot find when such an error occurs?

Sometimes I find that a long stdcall line with many symbols can make tracing a "symbol undefined" error troublesome.

06 Nov 2004, 16:45

pelaillo
Missing in inaction

Joined: 19 Jun 2003
Posts: 878
Location: Colombia

pelaillo 06 Nov 2004, 16:50

Where`s pushd macro?

06 Nov 2004, 16:50

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20516
Location: In your JS exploiting you and your system

revolution 06 Nov 2004, 19:57

Quote:

The PUSHD macro (in WIN32AX.INC) has the following line

06 Nov 2004, 19:57

pelaillo
Missing in inaction

Joined: 19 Jun 2003
Posts: 878
Location: Colombia

pelaillo 06 Nov 2004, 21:11

thanks

06 Nov 2004, 21:11

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