Re: [Elftoolchain-developers] strange behaviour of elf_update()

[Kai W. <kai...@gm...>]

Hi Luca,

On Tue, Mar 02, 2010 at 02:12:31PM +0100, Luca Pizzamiglio wrote:
> Hi to all.
> I'm Luca and I'm using libelf on FreeBSD 7.3 to develop a tool that
> manipulate ELF binaries. I hope that mailing list is right to post
> this problem.
> 
> My tool changes some information in the dynamic symbol table (using
> gelf_update_sym()), save the elf and quit.
> 
> elf_update(e, ELF_C_WRITE) fails with a DATA class error (Invalid data
> buffer descriptor).
> 
> Investigations revealed that _libelf_xlate() fails because src->d_buf is NULL.
> Further investigations revealed that the caller function
> _libelf_write_elf() when wants to write the program header table, use
> the e_phdr32 field of the _Elf struct. Seems that this field is not
> correctly initialized.
> As workaround I call gelf_getphdr() and the problem goes away.

Thanks for reporting this problem.

It should be already fixed by elftoolchain svn repository revsion 305.
However it's not yet been merged back to FreeBSD.

You can fetch the diff (try svn diff -c305 in trunk/libelf) and apply
it to the libelf in FreeBSD 7.3.

Cheers,
Kai