[Crash-utility] Patch to fix Seg Violation in parse_for_member

[Adrien Kunysz]

What about replacing that fprintf() with fprintf(pc->saved_fp, "%s",
buf) or even fputs(buf, pc->saved_fp)?

On Fri, Aug 10, 2012 at 2:55 PM, Dave Anderson <anderson at redhat.com> wrote:
>
>
> ----- Original Message -----
>> On Thu, 2012-08-09 at 16:23 -0600, Bob Montgomery wrote:
>> > If you change the
>> >      fprintf(pc->saved_fp, buf);
>> > lines to
>> >      print_verbatim(pc->saved_fp, buf);
>> >
>> > Then I won't get:
>> >
>> > crash> sk_buff.head ffff88012014dc80
>> > Segmentation fault
>> >
>> > When I need to get:
>> >
>> > crash> sk_buff.head ffff88012014dc80
>> >   head = 0xffff880121267000 "\"%s %s %s\", got type \"%s\""
>> >
>> >
>> > Patch attached (6.0.8).
>> >
>> > I suspect performance will suffer a bit when I try to print
>> > 2 million of these...
>>
>> Wonder if it would be quicker on average to string search for "%" and
>> conditionally call print_verbatim???  I had lots of successful
>> fprintf's and only a small number of seg viol cases.
>>
>> Bob M.
>
> Hi Bob,
>
> Although in practice,
>
>  (1) parse_for_member() is rarely called "in quantity", and
>  (2) when it is called, it would only encounter this with "char *" members, and
>  (3) the string would also have to have a '%' in it.
>
> On the other hand, if you test the two print-types with a million calls,
> there's a significant performance hit.  But if a strstr() is done first
> on the string, there's virtually no hit at all if there's no '%' in it.
>
> So yes, I agree with you that the string-search/conditional call should be done.
> I'll add that to your patch, and queue it for crash-6.0.9.
>
> Thanks,
>   Dave
>
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