[Crash-utility] fix gdb_get_datatype cannot handle integer type

[Dave Anderson]

----- 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.

Dave