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Re: libelf RDWR and elf_newscn do not work

On Thu, 2013-10-10 at 17:34 +0200, Jiri Slaby wrote:
> On 10/10/2013 03:16 PM, Mark Wielaard wrote:
> > @@ -764,7 +765,8 @@ __elfw2(LIBELFBITS,updatefile) (Elf *elf, int change_bo, size_t shnum)
> >  	    (*shdr_fctp) (&shdr_data[scn->index],
> >  			  scn->shdr.ELFW(e,LIBELFBITS),
> >  			  sizeof (ElfW2(LIBELFBITS,Shdr)), 1);
> > -	  else if (elf->state.ELFW(elf,LIBELFBITS).shdr == NULL)
> > +	  else if (elf->state.ELFW(elf,LIBELFBITS).shdr == NULL
> > +		   || (elf->flags & ELF_F_DIRTY))
> I seem to miss where is elf->flags |= ELF_F_DIRTY in the newscn path...
> Should it be added too?

No, I don't think it should be set there. But you do raise a good point.
I had assumed that since newscn increases e_shnum it would mark the
whole Elf dirty. But now that I look it doesn't seem to. if e_shnum is
changed then the ehdr->flags do get ELF_F_DIRTY set (see elf_update ->
elf32_updatenull). But I cannot immediately see why the whole Elf file
is marked dirty (although it is in your example).

So either I am missing something that makes it correct anyway, or the
check should be against ehdr->flags. I am digging...



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