static variables

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Alessio

Joined: 26 Sep 2003
Posts: 35
Location: Viterbo, Italy

Alessio 12 Nov 2008, 10:27

Hi,

sorry for my weird question but I've not found posts through search option.
I'm switching from C to assembler and my question is:

there is a way to create static variables into procs ?
or static variables should be considered global variables as defined in .data section ?

thanks.

12 Nov 2008, 10:27

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20451
Location: In your JS exploiting you and your system

revolution 12 Nov 2008, 11:01

Static (global) variables are best placed in one of your data sections.

Proc local variables are on the stack so they can't be static.

12 Nov 2008, 11:01

sleepsleep

Joined: 05 Oct 2006
Posts: 13061
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sleepsleep 12 Nov 2008, 20:18

i don't know whether if you has the option to create a new section with readable but no writeable option.

something like.

section '.data2' data2 readable

but nothing is impossible in programming right...

12 Nov 2008, 20:18

windwakr

Joined: 30 Jun 2004
Posts: 827

windwakr 12 Nov 2008, 21:00

I believe the correct name for a readable only data section is '.rdata'

section '.rdata' data readable

Here is a simple example:

Code:

format PE GUI 4.0
entry start

include 'win32a.inc'

section '.data' data readable writeable
buf rb 256

section '.rdata' data readable
number dd 2
fmt db '%u',0
title db '...',0

section '.code' code readable executable
start:
cinvoke wsprintf,buf,fmt,[number]
invoke MessageBox,NULL,buf,title,MB_OK
invoke ExitProcess,0

section '.idata' import data readable writeable

  library kernel32,'KERNEL32.DLL',\
          user32,'USER32.DLL'

  include 'api/kernel32.inc'
  include 'api/user32.inc'

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12 Nov 2008, 21:00

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20451
Location: In your JS exploiting you and your system

revolution 19 Nov 2008, 14:10

windwakr wrote:

I believe the correct name for a readable only data section is '.rdata'

I don't think there is any such thing as a "correct name" for sections. Perhaps a better way of describing it would be to say "the commonly used name ...". Sections names are arbitrary and no meaning should be implied when reading them.

19 Nov 2008, 14:10

bitRAKE

Joined: 21 Jul 2003
Posts: 4073
Location: vpcmpistri

bitRAKE 19 Nov 2008, 17:01

They can even be blank - OS doesn't use them.

19 Nov 2008, 17:01

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