mapserv segfaults

[Sean Gillies]

Type "where" at the gdb prompt after the segfault and post the result
for us.  Sorry, I should have mentioned this before.

As you are not specifying height/width and bbox in your query string,
the default values specified in your map config file will be very
important.  Can you attach your map file as well?

cheers,
Sean

On Feb 10, 2005, at 9:47 AM, John C Cartwright wrote:

> Hi Sean,
>
> thanks for the suggestion. here's the output:
>
> (gdb) run
> Starting program: /extra/contrib/apache/cgi-bin/mapserv-debug
> [Thread debugging using libthread_db enabled]
> [New Thread -1218604192 (LWP 19250)]
> [Thu Feb 10 09:40:19 2005].204455 msWMSLoadGetMapParams(): enabling
> non-square pixels.[Thu Feb 10 09:40:19 2005].208427 msDrawMap():
> kicking
> into non-square pixel preserving mode.
> Program received signal SIGSEGV, Segmentation fault.
> [Switching to Thread -1218604192 (LWP 19250)]
> 0x0095b0d1 in realloc () from /lib/tls/libc.so.6
>
> Here's the query string:
>
> map=/extra/contrib/apache/htdocs/mapserver/wms_wfs/
> wms.map&SERVICE=WMS&VERSION=1.1.1&REQUEST=GetMap&LAYERS=relief,cities_p
> oly,counties,states,roads
>
> and this is a RedHat ES 3 system (kernel 2.4.21-27.0.1.ELsmp)
>
> Where should I go from here?
>
> Thanks again!
>
> -- john
>
>
> Sean Gillies wrote:
>> John, add a
>>
>>   DEBUG ON
>>
>> to the Map-level block in your map config file.  This will write
>> messages to stderr, including names of layers being accessed.  This
>> should let you know which layer (if any) is associated with the
>> segfault.
>>
>> Now that you've recompiled, run mapserv under gdb exactly as Steve
>> Woodbridge described.  This time gdb should give a more detailed
>> description of the location of the memory error including all the
>> MapServer functions that have been called.  Give us a look at that and
>> we can try to figure out what's going on.
>>
>> cheers,
>> Sean
>>
>> On Feb 9, 2005, at 5:28 PM, John C Cartwright wrote:
>>
>>> Thanks, Sean. I recompiled with debugging, can you provide me a
>>> little
>>> guidance on what would be helpful to get out of gdb?
>>>
>>> ...
>>> Thanks again for your patience and help!
>>>
>>> -- john
>>>
>>
>>> Sean Gillies wrote:
>>>
>>>> John,
>>>> Looks to me like you need to re-config mapserver with
>>>> --enable-debug so
>>>> that gdb can tell us more about the calling stack.
>>>> cheers,
>>>> Sean
>>>> On Feb 9, 2005, at 5:08 PM, John C Cartwright wrote:
>>>>
>>>>> Hi Steve,
>>>>>
>>>>> thanks for the prompt response and the suggestion.
>>>>>
>>>>> gdb is just telling me the error occurred in memory allocation, but
>>>>> this
>>>>> is not helping me much:
>>>>>
>>>>> (gdb) run
>>>>> Starting program: /extra/contrib/apache/cgi-bin/mapserver-4.4.1
>>>>> [Thread debugging using libthread_db enabled]
>>>>> [New Thread -1218617216 (LWP 8708)]
>>>>>
>>>>> Program received signal SIGSEGV, Segmentation fault.
>>>>> [Switching to Thread -1218617216 (LWP 8708)]
>>>>> 0x039ba0d1 in realloc () from /lib/tls/libc.so.6
>>>>>
>>>>> I was hoping to tell what request parameter or map configuration
>>>>> element
>>>>> might be causing trouble. Can you think of any way for me to pursue
>>>>> this
>>>>> at a higher level?
>>>>>
>>>>> Thanks!
>>>>>
>>>>> -- john
>>>>>
>>>>>
>>>>>
>>>>> Stephen Woodbridge wrote:
>>>>>
>>>>>> John,
>>>>>>
>>>>>> You can run mapserver cgi at the command line, but you need to
>>>>>> set up
>>>>>> the environment variables first, like
>>>>>>
>>>>>> export REQUEST_METHOD=GET
>>>>>> export QUERY_STRING="...."
>>>>>> gdb mapserv
>>>>>> run
>>>>>>
>>>>>> set your QUERY_STRING appropriately
>>>>>>
>>>>>> -Steve W.
>>>>>
>>>>>
>>>>>
>>>
>>
>
>
--
Sean Gillies
sgillies at frii dot com
http://users.frii.com/sgillies