[Crash-utility] fix gdb_get_datatype cannot handle integer type

[Lei Wen]

Dave,

On Fri, Mar 8, 2013 at 4:12 AM, Dave Anderson <anderson at redhat.com> wrote:
>
>
> ----- Original Message -----
>> Dave,
>>
>> On Thu, Mar 7, 2013 at 12:56 AM, Dave Anderson <anderson at redhat.com>
>> wrote:
>> >
>> >
>> > ----- Original Message -----
>> >> Dave,
>> >>
>> >> On Wed, Mar 6, 2013 at 10:04 PM, Dave Anderson
>> >> <anderson at redhat.com>
>> >> wrote:
>> >> >
>> >> >
>> >> > ----- Original Message -----
>> >> >> Hi Dave,
>> >> >>
>> >> >> Current when pass integer type to gdb_get_datatype in crash, it would return
>> >> >> req->typecode=0 and req->length=0.
>> >> >>
>> >> >> As it only allow TYPE_CODE_ENUM to be passed. here is a patch for fixing it.
>> >> >> Do you think it could be merged?
>> >> >
>> >> > That's the OP_VAR_VALUE section -- what is the command that you're using that
>> >> > ends up passing an integer type to the function?  And what problem does it
>> >> > cause?
>> >>
>> >> I enhance whatis command in my local code base to show the function's original variant name.
>> >> If not with my change, the original result is:
>> >> int schedule_delayed_work_on(int , struct delayed_work * , long unsigned int );
>> >> With my change, the result becomes:
>> >> int schedule_delayed_work_on(int cpu, struct delayed_work * dwork, long unsigned int delay);
>> >>
>> >> So it look nicer, right? :)
>> >
>> > I guess -- but when I add the patch, it doesn't look any different, so presumably
>> > it only applies w/respect to your enhanced whatis command...
>> >
>> >>
>> >> But I meet an issue that whatis is not intent for showing function prototype only, but for
>> >> structure/union/integer type.
>> >>
>> >> So I need to add arg_to_datatype in whatis_variable to tell the passed data's type to whether
>> >> call gdb's function for exacting out the function parameter's name.
>> >>
>> >> Then I face the bug as I reported...
>> >
>> > It's not really a bug because that code path was meant for usage by the
>> > enumerator_value() function.  So it makes me a bit nervous to modify it
>> > for code that only your enhanced whatis command would ever see.
>> >
>> > Would your code work if only the req->typecode and req->length fields where
>> > passed back?  (i.e., without tinkering with the req->value and req->tagname
>> > fields in the non-enum case?)  Like this:
>> >
>> > --- gdb-7.3.1/gdb/symtab.c.orig
>> > +++ gdb-7.3.1/gdb/symtab.c
>> > @@ -5054,8 +5054,9 @@ gdb_get_datatype(struct gnu_request *req
>> >                 if (gdb_CRASHDEBUG(2))
>> >                         console("expr->elts[0].opcode:
>> >                         OP_VAR_VALUE\n");
>> >                 type = expr->elts[2].symbol->type;
>> > +               req->typecode = TYPE_CODE(type);
>> > +               req->length = TYPE_LENGTH(type);
>> >                 if (TYPE_CODE(type) == TYPE_CODE_ENUM) {
>> > -                       req->typecode = TYPE_CODE(type);
>> >                         req->value = SYMBOL_VALUE(expr->elts[2].symbol);
>> >                         req->tagname = TYPE_TAG_NAME(type);
>> >                         if (!req->tagname) {
>> >
>>
>> This seems also works for me.
>
> All right, I'll merge the patch as shown above.  I cannot seem to find
> another pathway to get it other than via enumerator_value(), so it
> should be safe.
>

Thanks for accepting the patch.
Do you have any interest for my whatis changes, that is add parameter name
showing for function symbol?
If yes, I also could make a patch for it.

Thanks,
Lei