Re: [Nasm-devel] Override extern with global for header files

[Lars M. <lar...@te...>]

Hi,
today and yesterday I worked a bit at the feature we previously talked 
about.
This is not as easy as it might seems to be.

It took very long for me to understand the programm mechanics. Now I'm 
at the following point:
I can record extern definitions and prevent nasm from passing them to 
the ofmt. Although a redefinition as global is possible and they were 
treated as "unseen" labels. So the old function of a global label still 
works. There is just one problem: when passing the recorded extern 
labels, exept those wich are globals now, after the assembling is done, 
then the reloc adresses are broken in the output file. I guess this is 
because while assembling nasm is unable to resolve the label references. 
I would fix this, but I have no idea where and when this resolving takes 
places?


Just to make the problem clearer:

nasm -f elf test\externdef.asm

[extern externFunc]
[extern externFunc2]
[extern myFunc]

[global myFunc]

[section .text use32 class=code]

   ; just some senseless code to create references and relocs
   myFunc:
     push ebp
     mov ebp, esp
   .local:
     mov eax, 0x01
     jmp .local
     leave
     ret 4
   abc:
     call [externFunc]
     call [externFunc2]
     call [myFunc]
     ret 4




objdump -x test\externdef.o
nasm-2.11.05\test\externdef.o:     file format elf32-i386
nasm-2.11.05\test\externdef.o
architecture: i386, flags 0x00000011:
HAS_RELOC, HAS_SYMS
start address 0x00000000

Sections:
Idx Name          Size      VMA       LMA       File off  Algn
   0 .text         00000023  00000000  00000000  00000130  2**4
                   CONTENTS, ALLOC, LOAD, RELOC, READONLY, CODE
SYMBOL TABLE:
00000000 l    df *ABS*  00000000 test\externdef.asm
00000000 l    d  .text  00000000 .text
00000003 l       .text  00000000 myFunc.local
0000000e l       .text  00000000 abc
00000000         *UND*  00000000 externFunc
00000000         *UND*  00000000 externFunc2
00000000 g       .text  00000000 myFunc


RELOCATION RECORDS FOR [.text]:
OFFSET   TYPE              VALUE
00000010 R_386_32          myFunc
00000016 R_386_32          myFunc
0000001c R_386_32          myFunc