[osg-users] Call to readNodeFile works in osg 1.2, segfaults in osg 2.0

[Robert Osfield]

Hi Ian,

The plugins should produce e FILE_NOT_HANDLED in the case of trying to
load a file format that is not directly handled by the plugin, if it
isn't doing this then this is a bug.  The question then turns to which
plugin is not correctly returning a FILE_NOT_HANDLED.

What plugins are loaded in memory when this error occurs?  Use the env
 OSG_NOTFIY_LEVEL=DEBUG to find out what plugins are being loaded.
This should also give you an idea which plugin is the culprit.

Robert.

On 8/15/07, zeilstra at gdls.com <zeilstra at gdls.com> wrote:
> I have been working on moving some code from osg 1.2 to 2.0.  It has largely
> gone smoothly but there is an issue with a call to readNodeFile.  In this
> particular case, the filename being passed to readNodeFile is the name of an
> image file, and so I expect the read to fail and return a null pointer.  (I
> then test for this and conditionally try to read the same file as an image
> file.  It's a hack but it lets me handle map images and topographic data
> with the same function.)  However, when I compile this code against the osg
> 2.0 libraries, the result is a segmentation fault.  I ran the program in gdb
> and was able to examine the stack, the relevant portion of which I have
> reproduced below.
>
> #0  in __dynamic_cast () from /usr/lib/libstdc++.so.6
> #1  in osgDB::ReaderWriter::ReadResult::getNode (this)
>     at OpenSceneGraph/src/osgDB/ReaderWriter.cpp:22
> #2  in osgDB::ReaderWriter::ReadResult::validNode (this)
>     at OpenSceneGraph/include/osgDB/ReaderWriter:158
> #3  in osgDB::Registry::ReadNodeFunctor::isValid (this,
>     readResult)
>     at OpenSceneGraph/src/osgDB/Registry.cpp:1280
> #4  in osgDB::Registry::read (this,
>     readFunctor)
>     at OpenSceneGraph/src/osgDB/Registry.cpp:1440
> #5  in osgDB::Registry::readImplementation (this,
>     readFunctor, useObjectCache)
>     at OpenSceneGraph/src/osgDB/Registry.cpp:1508
> #6  in osgDB::Registry::readNodeImplementation (this,
>     fileName, options)
>     at OpenSceneGraph/src/osgDB/Registry.cpp:1725
> #7  in osgDB::Registry::readNode (this,
>     fileName, options)
>     at OpenSceneGraph/include/osgDB/Registry:207
> #8  in osgDB::readNodeFile (filename, options)
>     at OpenSceneGraph/src/osgDB/ReadFile.cpp:60
> #9  in osgDB::readNodeFile (filename)
>     at OpenSceneGraph/include/osgDB/ReadFile:107
>
> In frame 1, I checked the fields of the ReadResult object, and noted that
> they were mostly uninitialized, except for _status:
>
> _status = osgDB::ReaderWriter::ReadResult::FILE_NOT_HANDLED
>
> I guess that the segfault comes from trying to dynamic_cast an invalid
> address.  Is this an error in the osg code, or should I not be invoking
> readNodeFile on a non-model file?
>
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