[How?]MS COFF + dll export

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roxaz

Joined: 27 Jul 2008
Posts: 25

roxaz 18 Sep 2009, 19:58

Im in need of exporting making dll export of function written in asm (MS COFF). Microsoft c++ compiler.. Idea was to make simpe function, declare it as public and export it using def file, however i get unresolved external saying that my function does not exist. How do i make dll export from MS COFF file and manually set ordinal for that export?

18 Sep 2009, 19:58

SFeLi

Joined: 03 Nov 2004
Posts: 138

SFeLi 20 Sep 2009, 05:17

Maybe your forgot to mangle a name of your function?

Code:

; foo.asm
        format  ms coff

public DllEntryPoint as '__DllMainCRTStartup@12'
public Foo as '_Foo@8'

DllEntryPoint:
        xor     eax,eax
        inc     eax
        retn    0x0c

Foo:
        mov     eax,[esp+0x04]
        add     eax,[esp+0x08]
        retn    0x08

; foo.def
LIBRARY FOO
EXPORTS
  Foo

; to link it:
link /DLL /DEF:foo.def foo.obj

And here you can read about setting ordinals in def-files.

20 Sep 2009, 05:17

roxaz

Joined: 27 Jul 2008
Posts: 25

roxaz 20 Sep 2009, 07:49

well yah i did not mangle names, thought i got to provide exact name in def file as it is in def..

EDIT:
question tho.. i still have to specify mangled name in def file, so why cant i have unmangled name and specify it in def file? My def is like this:

Code:

EXPORTS
    SysAllocString=___func__SysAllocString@0 @2

20 Sep 2009, 07:49

SFeLi

Joined: 03 Nov 2004
Posts: 138

SFeLi 20 Sep 2009, 18:45

You should have the same public name as you specify in .def file:

Code:

DEF: SysAllocaString @2
ASM: public SysAllocString

DEF: SysAllocaString=SysAllocString @2
ASM: public SysAllocString as 'SysAllocString' (any combinations)

DEF: SysAllocString=___func__SysAllocString@0 @2
ASM: public mySysAllocString as '___func__SysAllocString@0'

20 Sep 2009, 18:45

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