Segmentation Fault using VFS + wezu's deferred renderer in loader.load_model

[ellie]

I get a Segmentation Fault in my project where I add additional model loader paths and I also use wezu's deferred renderer ( https://github.com/wezu/p3d_auto_deferred_shader ) which wraps the loader built-in in some unusual way.

This line crashes in wezu's code (which I know from print debugging):

model = loader.load_model("models/cone")

This is what valgrind captures for the loader.load_model() crash:

==17285== Process terminating with default action of signal 11 (SIGSEGV)
==17285== Access not within mapped region at address 0x0
==17285== at 0x1350F35C: std::ostream::sentry::sentry(std::ostream&) (in /usr/lib64/libstdc++.so.6.0.22)
==17285== by 0x1350F75D: std::ostream::write(char const*, long) (in /usr/lib64/libstdc++.so.6.0.22)
==17285== by 0x12D1955A: VirtualFileSimple::copy_file(VirtualFile*) (in /usr/lib64/panda3d/libpandaexpress.so.1.10)
==17285== by 0x12D19B52: VirtualFileSimple::rename_file(VirtualFile*) (in /usr/lib64/panda3d/libpandaexpress.so.1.10)
==17285== by 0x12D25DDC: VirtualFileSystem::rename_file(Filename const&, Filename const&) (in /usr/lib64/panda3d/libpandaexpress.so.1.10)
==17285== by 0x1287681A: BamCache::store(BamCacheRecord*) (in /usr/lib64/panda3d/libpanda.so.1.10)
==17285== by 0x124A1540: Loader::try_load_file(Filename const&, LoaderOptions const&, LoaderFileType*) const (in /usr/lib64/panda3d/libpanda.so.1.10)
==17285== by 0x124A21A4: Loader::load_file(Filename const&, LoaderOptions const&) const (in /usr/lib64/panda3d/libpanda.so.1.10)
==17285== by 0x113B63DD: Dtool_Loader_load_sync_1555(_object*, _object*, _object*) (in /usr/lib64/python3.5/site-packages/panda3d/core.cpython-35m-x86_64-linux-gnu.so)
==17285== by 0x4EE7F08: PyCFunction_Call (in /usr/lib64/libpython3.5m.so.1.0)
==17285== by 0x4F5FE4F: PyEval_EvalFrameEx (in /usr/lib64/libpython3.5m.so.1.0)
==17285== by 0x4F619B2: ??? (in /usr/lib64/libpython3.5m.so.1.0)

[rdb (rdb)]

Please attach a test case.

[ellie (et1234567)]

I managed to make a test case!

WARNING: this test case creates a subfolder with a dummy file and an empty folder in /tmp which it doesn't clean up (that would be kinda hard after a crash, lol) - for more details see comment inside the code file at the top

[rdb (rdb)]

Now no longer gives a crash; just an error. Please refrain from setting up recursive mounts on / or you may risk tearing a hole in the spacetime continuum.