Re: [PATCH] Catch exception in value_rtti_indirect_type

[Pedro Alves <palves at redhat dot com>]

On 09/20/2014 02:02 AM, Simon Marchi wrote:
> In the situation described in bug 17416 [1], 

Could you paste that in the commit log please?

> an exception thrown in
> value_ind can propagate too far and leave an half-built variable object,
> leading to a wrong state. This patch adds a TRY_CATCH to catch it and
> makes value_rtti_indirect_type return NULL in that case, meaning
> that the type of the pointed object could not be found.
> 
> If you want, I can also integrate the test case provided in the bug

Yes please.

> description. I just don't know how to name it without giving it a
> ridiculously long name such as
> mi-var-list-children-with-print-object-on-and-a-null-pointer-to-a-structure-that-contains-a-pointer-to-a-structure.exp.

Perhaps mi-var-list-children-invalid-grandchild.exp.

> 
> I tested the change on my machine, Ubuntu 14.10 x86-64.
> 
> gdb/Changelog:
> 
> 	* valops.c (value_rtti_indirect_type): Catch exception thrown by
> 	value_ind.
> 
> [1] https://sourceware.org/bugzilla/show_bug.cgi?id=17416
> ---
>  gdb/valops.c | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/gdb/valops.c b/gdb/valops.c
> index e1decf0..c1a0c86 100644
> --- a/gdb/valops.c
> +++ b/gdb/valops.c
> @@ -3609,7 +3609,18 @@ value_rtti_indirect_type (struct value *v, int *full,
>    if (TYPE_CODE (type) == TYPE_CODE_REF)
>      target = coerce_ref (v);
>    else if (TYPE_CODE (type) == TYPE_CODE_PTR)
> -    target = value_ind (v);
> +    {
> +      volatile struct gdb_exception except;
> +
> +      TRY_CATCH (except, RETURN_MASK_ERROR)
> +        {
> +	  target = value_ind (v);
> +        }
> +      if (except.error == MEMORY_ERROR)
> +	  return NULL;
> +      else if (except.error != GDB_NO_ERROR)
> +	throw_exception (except);

Indentation looks odd.  But, could you write it like this instead ?

      volatile struct gdb_exception except;

      TRY_CATCH (except, RETURN_MASK_ERROR)
        {
	  target = value_ind (v);
        }
      if (except.reason < 0)
        {
          if (except.error == MEMORY_ERROR)
            {
              /* Add comment here.  */
	      return NULL;
            }
  	  throw_exception (except);
        }

Thanks,
Pedro Alves