[fdo-users] How does FDO handle invalid fgf geometries?

[Dan Stoica]

Can you please add my findings too? They will be helpful for whoever will fix it.

Thanks.

-----Original Message-----
From: fdo-users-bounces at lists.osgeo.org [mailto:fdo-users-bounces at lists.osgeo.org] On Behalf Of Jackie Ng
Sent: Friday, August 22, 2008 10:03 AM
To: fdo-users at lists.osgeo.org
Subject: RE: [fdo-users] How does FDO handle invalid fgf geometries?


For reference:

http://trac.osgeo.org/fdo/ticket/382

- Jackie


Dan Stoica wrote:
>
> This is a bug and needs fixing. It is a bug because GetText() is supposed
> to do a simple dump. What a dump has to do with topological validation?
> None.
>
> Therefore, filing a ticket is the right thing to do.
>
> Dan.
>
> -----Original Message-----
> From: fdo-users-bounces at lists.osgeo.org
> [mailto:fdo-users-bounces at lists.osgeo.org] On Behalf Of Jackie Ng
> Sent: Thursday, August 21, 2008 11:57 PM
> To: fdo-users at lists.osgeo.org
> Subject: RE: [fdo-users] How does FDO handle invalid fgf geometries?
>
>
> I strongly suspected that it was some other error than running out of
> memory.
>
> Good to know my suspicions are confirmed.
>
> - Jackie
>
>
> Dan Stoica wrote:
>>
>> Did some investigations on this matter. Turns out that:
>>
>> a) the polygon in question has a ring which is not closed.
>> b) the geometry factory throws an appropriate exception "Open ring"
>> c) the exception is not caught by GetText()
>> d) for some odd reason the exception is turned into "memory allocation
>> error"
>>
>> Therefore, the quick solution for Jackie is to catch the exception.
>>
>> Going forward, we might want to get rid of the 'is polygon closed?'
>> test...
>>
>>
>> Dan.
>>
>> -----Original Message-----
>> From: fdo-users-bounces at lists.osgeo.org
>> [mailto:fdo-users-bounces at lists.osgeo.org] On Behalf Of Mateusz Loskot
>> Sent: Thursday, August 21, 2008 10:51 AM
>> To: FDO Users Mail List
>> Subject: Re: [fdo-users] How does FDO handle invalid fgf geometries?
>>
>> Jackie Ng wrote:
>>> Hi All,
>>>
>>> How does FDO handle invalid FGF binary data?
>>
>> Jackie,
>>
>>  From my experience, I've observed that FDO does not strictly
>> validate FGF/WKB input on geometry creation.
>> Actually, GeometryFactory checks if WKB stream has minimal length of 9
>> bytes and it does not prevent to create geometry from bytes stream of
>> garbage.
>>
>> Here is a small test of valid and invalid WKB input (see main function):
>>
>> http://mateusz.loskot.net/tmp/fdo/test_geometry_factory.cpp.html
>>
>> This is the result of 3 test cases included in the test:
>>
>> Expected WKT: POINT(15.123 21.456)
>> Output WKT  : POINT (-7.84591113289983e+298 0)
>>
>> Expected WKT: POINT(15.123 21.456)
>> Output WKT  : POINT (15.123 21.456)
>>
>> *** FDO Error:
>>    *** (.\Src\Geometry\Fgf\GeometryFactory.cpp: 568)
>> FDO_1_INVALID_INPUT_ON_CLASS_CREATION
>>
>>
>> Best regards,
>> --
>> Mateusz Loskot, http://mateusz.loskot.net
>> Charter Member of OSGeo, http://osgeo.org
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