Re: Question about core files

[Holger Kiehl <Holger.Kiehl@dwd.de>]

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Hello Manish

First, sorry for the late responce!

On Wed, 7 Oct 2009, Manish Katiyar wrote:

> On Wed, Oct 7, 2009 at 7:51 PM, Holger Kiehl <Holger.Kiehl@dwd.de> wrote:
>> Hello Manish
>>
>> On Wed, 7 Oct 2009, Manish Katiyar wrote:
>>
>>> Hi Holger,
>>>
>>> I don't have the source code, so a bit hard to guess. But you can try
>>> to find out which member of your fsa structure is at offset 236 (0xec)
>>> and look around those lines in the function where you are accessing
>>> that member.
>>>
>>> I am trying to download the AFD source code, which looks like it will
>>> take ages on my slow broadband. Hopefully I can help after that.
>>>
>> If you download, please take afd-1.4.0-0.20.beta.tar.bz2 because that
>> is the one that caused the error. You can get it from:
>>
>>   ftp://ftp.dwd.de/pub/afd/development/afd-1.4.0-0.20.beta.tar.bz2
>>
>> You will find the relevant code in src/fd.c.
>
> Hi Holger,
>
> (gdb) set $offset = (int)(&((struct filetransfer_status *)0)->host_status)
> (gdb) p $offset
> $5 = 236
> (gdb) p/x 236
> $6 = 0xec
>
> host_status is at offset 236. In the function start_process I can see
> that this is used at places by dereferencing below
> "fsa[fsa_pos].host_status ".
>
> At this point my guess would be that you are getting fsa_pos as
> something illegal ie.. probably you are trying to access beyond the
> array. Since this is an input to the function, you can just check its
> value at the start and assert if that is ok and within reasonable
> range.
>
> HTH
>
Many thanks for finding this out! I think I now, with your help, have a
clue where the error could be. Is there a way to find out what value
fsa_pos had at that time? If it was -1 then it is definitely the error
I am thinking of, but if it is something else then I don't know.

Again many thanks for the valuable help!

Regards,
Holger