CODEWITHSUNDEEP
assemblynasmld
Barbo24
Barbo24

Reputation: 49

linking assembler generated obj file

I am trying to learn (or at least understand) assembly on windows. I found this Hello World example somewhere and I want to make an .exe out of it just to be sure I have everything set up correctly. For people that will post other Hello World examples I want to make clear I am looking for one with direct windows api calls.

        global  _start
        extern  _ExitProcess@4
        extern  _GetStdHandle@4
        extern  _WriteConsoleA@20

        section .data
msg:    db      'Hello, World', 10
handle: db      0
written:
        db      0

        section .text
_start:
        ; handle = GetStdHandle(-11)
        push    dword -11
        call    _GetStdHandle@4
        mov     [handle], eax

        ; WriteConsole(handle, &msg[0], 13, &written, 0)
        push    dword 0
        push    written
        push    dword 13
        push    msg
        push    dword [handle]
        call    _WriteConsoleA@20

        ; ExitProcess(0)
        push    dword 0
        call    _ExitProcess@4

I assemble it successfully like so

nasm -fwin32 hello.asm

Then when I try to link it with ld like so

ld hello.obj -lkernel32

It produces an executable but when I try to run it I get this

Program 'a.exe' failed to run: The specified executable is not a valid application for this OS platform.At line:1 char:1
+ .\a.exe
+ ~~~~~~~.
At line:1 char:1
+ .\a.exe
+ ~~~~~~~
    + CategoryInfo          : ResourceUnavailable: (:) [], ApplicationFailedException
    + FullyQualifiedErrorId : NativeCommandFailed

I even downloaded ALINK but whenever I try to link it like so

ALINK hello.obj C:\Windows\System32\kernel32.dll

I get this output

ALINK v1.6 (C) Copyright 1998-9 Anthony A.J. Williams.
All Rights Reserved

Loading file .\programs\hello.obj
Loading file C:\Windows\System32\kernel32.dll
Unsupported CPU type for module

what flags do I have to pass to the linkers, what am I doing wrong?

Upvotes: 1

Views: 920

Answers (1)

vitsoft
vitsoft

Reputation: 5775

You are linking it wrong. Unlike FASM or €ASM, the linker ALINK is not capable to fetch import information from Dynamic Linked Library on the fly, it needs an import library. One such library WIN32.lib is shipped with ALINK or you can generate it yourself. e.g. by dll2lib or similar tool.

Then you should fix errors in your source:

  1. Memory variables handle and written should be DWORD, not BYTE.
  2. Remove decoration from names of imported functions. Use ExitProcess instead of _ExitProcess@4 etc., exactly as they are defined at Microsoft API doc

Make your executable with

nasm -fwin32 barbo24.asm
alink barbo24.obj WIN32.lib -oPE -entry _start -subsys con
barbo24.exe

If it doesn't write Hello, world, check and debug it with

peview.exe barbo24.exe
ollydbg barbo24.exe

Upvotes: 3

Related Questions