Re: [PATCH 1/3] Add fbsd_nat_add_target.

[John Baldwin <jhb@freebsd.org>]

On Monday, April 27, 2015 08:10:18 PM Pedro Alves wrote:
> On 04/26/2015 02:24 AM, John Baldwin wrote:
> > Add a wrapper for add_target in fbsd-nat.c to override target operations
> > common to all native FreeBSD targets.
> > 
> > gdb/ChangeLog:
> > 
> > 	* fbsd-nat.c (fbsd_pid_to_exec_file): Mark static.
> > 	(fbsd_find_memory_regions): Mark static.
> > 	(fbsd_nat_add_target): New function.
> > 	* fbsd-nat.h: Export fbsd_nat_add_target and remove prototypes for
> > 	fbsd_pid_to_exec_file and fbsd_find_memory_regions.
> > 	* amd64fbsd-nat.c (_initialize_amd64fbsd_nat): Use fbsd_nat_add_target.
> > 	* i386fbsd-nat.c (_initialize_i386fbsd_nat): Likewise.
> > 	* ppcfbsd-nat.c (_initialize_ppcfbsd_nat): Likewise.
> > 	* sparc64fbsd-nat.c (_initialize_sparc64fbsd_nat): Likewise.
> 
> OOC, any reason you didn't instead do it like:
> 
> struct target_ops *
> fbsd_nat_target (void)
> {
>   struct target_ops *t = inf_ptrace_target ();
> 
>   t->to_pid_to_exec_file = fbsd_pid_to_exec_file;
>   t->to_find_memory_regions = fbsd_find_memory_regions;
>   return t;
> }
> 
> and then use fbsd_nat_target instead of inf_ptrace_target
> directly?
> 
> This maps a little better to a C++ world.
> 
> linux-nat.c does it the way you did as it keeps a separate
> linux_ops target instance around.

I was probably just using linux-nat.c as a reference.  One thing that
confuses me about the linux-nat target is that it keeps linux_ops
around so that it can call the original methods that it overrides,
and yet for a few methods it also uses a local 'super_foo' variable
to call an original method.  I think that those are both doing the
same thing, but perhaps there is some subtlety I'm missing?

I do use a 'super_wait' to call ptrace's wait method in the second
patch in this series, so I could certainly change this to return a
target rather than modifying an existing one if that is preferred.

-- 
John Baldwin