[opcodes] bfd_flavour

[opcodes] bfd_flavour

[Emmanuel Fleury]

Hi,

I'm trying to use libopcodes for one of my project and I stumbled into
the bfd_flavour parameter.

I tried to code a small disassembler (similar to objdump but way
simpler) with and without setting the bfd_flavour with no significant
difference on my tool.

My question is: What bad can happen if I omit to set the flavour of the
binary that I'm disassembling when using the disassembler_fn of
libopcodes ? (and, subsequently, what is used the bfd_flavour for in
libopcodes ?)

Regards
-- 
Emmanuel Fleury

And then it happened... a door opened to a world... rushing through the
phone line like heroin through an addict's veins, an electronic pulse is
sent out, a refuge from the day-to-day incompetencies is sought...
a board is found.

This is it... this is where I belong...
  -- The Mentor (January 8, 1986, Phrack 7)

Re: [opcodes] bfd_flavour

[Alan Modra]

On Mon, Jun 06, 2011 at 11:23:59PM +0200, Emmanuel Fleury wrote:
> My question is: What bad can happen if I omit to set the flavour of the
> binary that I'm disassembling when using the disassembler_fn of
> libopcodes ?

Is your target one of those that show up below (on the info->flavour
matches, not the bfd_asymbol_flavour matches)?  If not, you don't
need to worry.

> (and, subsequently, what is used the bfd_flavour for in
> libopcodes ?)

$ grep flavour *.[ch]
alpha-dis.c:  if (info->flavour == bfd_target_evax_flavour)
arm-dis.c:      && bfd_asymbol_flavour (*info->symtab) == bfd_target_elf_flavour)
arm-dis.c:      if (bfd_asymbol_flavour (*info->symbols) == bfd_target_coff_flavour)
arm-dis.c:      else if (bfd_asymbol_flavour (*info->symbols) == bfd_target_elf_flavour
arm-dis.c:  if (info->flavour == bfd_target_elf_flavour
dis-init.c:  info->flavour = bfd_target_unknown_flavour;
mips-dis.c:  if (info->flavour == bfd_target_elf_flavour && info->section != NULL)
mips-dis.c:	  if (info->flavour == bfd_target_unknown_flavour
mips-dis.c:		&& info->flavour == bfd_target_unknown_flavour)
mips-dis.c:	if (!jalx && info->flavour == bfd_target_unknown_flavour)
mips-dis.c:	  && bfd_asymbol_flavour (*info->symbols) == bfd_target_elf_flavour
sh64-dis.c:	  && bfd_asymbol_flavour (info->symbols[0]) == bfd_target_elf_flavour
sh64-dis.c:      && bfd_get_flavour (info->section->owner) == bfd_target_elf_flavour)
sh64-dis.c:      && bfd_asymbol_flavour (info->symbols[0]) == bfd_target_elf_flavour
sh64-dis.c:      && bfd_asymbol_flavour (info->symbols[0]) == bfd_target_elf_flavour
sh-dis.c:	  && bfd_asymbol_flavour(*info->symbols) == bfd_target_coff_flavour)


-- 
Alan Modra
Australia Development Lab, IBM

Re: [opcodes] bfd_flavour

[Emmanuel Fleury]

Hi,

On 06/08/2011 04:29 PM, Alan Modra wrote:
> On Mon, Jun 06, 2011 at 11:23:59PM +0200, Emmanuel Fleury wrote:
>> My question is: What bad can happen if I omit to set the flavour of the
>> binary that I'm disassembling when using the disassembler_fn of
>> libopcodes ?
> 
> Is your target one of those that show up below (on the info->flavour
> matches, not the bfd_asymbol_flavour matches)?  

No, the flavour was more about the CPU sub-architecture and not about
the format of the binary. But, I think I got confused with some other
structure... Sorry for that, I need to take a second look at it.

> If not, you don't need to worry.

Excellent. Thanks a lot.

>> (and, subsequently, what is used the bfd_flavour for in
>> libopcodes ?)
> 
> $ grep flavour *.[ch]
> alpha-dis.c:  if (info->flavour == bfd_target_evax_flavour)
> arm-dis.c:      && bfd_asymbol_flavour (*info->symtab) == bfd_target_elf_flavour)
> arm-dis.c:      if (bfd_asymbol_flavour (*info->symbols) == bfd_target_coff_flavour)
> arm-dis.c:      else if (bfd_asymbol_flavour (*info->symbols) == bfd_target_elf_flavour
> arm-dis.c:  if (info->flavour == bfd_target_elf_flavour
> dis-init.c:  info->flavour = bfd_target_unknown_flavour;
> mips-dis.c:  if (info->flavour == bfd_target_elf_flavour && info->section != NULL)
> mips-dis.c:	  if (info->flavour == bfd_target_unknown_flavour
> mips-dis.c:		&& info->flavour == bfd_target_unknown_flavour)
> mips-dis.c:	if (!jalx && info->flavour == bfd_target_unknown_flavour)
> mips-dis.c:	  && bfd_asymbol_flavour (*info->symbols) == bfd_target_elf_flavour
> sh64-dis.c:	  && bfd_asymbol_flavour (info->symbols[0]) == bfd_target_elf_flavour
> sh64-dis.c:      && bfd_get_flavour (info->section->owner) == bfd_target_elf_flavour)
> sh64-dis.c:      && bfd_asymbol_flavour (info->symbols[0]) == bfd_target_elf_flavour
> sh64-dis.c:      && bfd_asymbol_flavour (info->symbols[0]) == bfd_target_elf_flavour
> sh-dis.c:	  && bfd_asymbol_flavour(*info->symbols) == bfd_target_coff_flavour)


Ok.

Regards
-- 
Emmanuel Fleury

Before software should be reusable, it should be usable.
  -- Ralph Johnson