Fix crash libpd_openfile due to lock

[pierreguillot]

It seems that libpd_openfile() needs to lock the global pd's mutex for writing otherwise because glob_evalfile() uses static variable and if several instances call this function it crashes.

[danomatika]

Thanks for checking this. Do we need both sys_lock and the globallock? I don't know, just checking.

[pierreguillot]

Yes because sys_lock() lock the instance and enables pd_this->pd_islocked = 1; then globallock() checks this value if (!pd_this->pd_islocked) bug("pd_globallock");

[pierreguillot]

I can also add my test (samples/c/pdtest_thread) from this branch but it's a bit dirty for the moment

[danomatika]

Adding a test is a good idea. I recently cleaned up the makefiles so they they should be easy to adapt. The plan in the future is to update libpd to use auto tools.

[danomatika]

Looks good. Let me know when you feel the PR is ready. I'm thinking we will also provide a libpd wrapper for pd_instance such as libpd_set_instance or something similar soon.

[pierreguillot]

I think it's ready for this PR. Sorry for the slowness :)

[danomatika]

If you use the current master branch, you could update the test to use the "libpd_*_instance" functions. Also, the main Makefile now has a "MULTI" build option so you no longer need to set PDINSTANCE and PDTHREADS in the test Makefile. Build libpd with multiple instance support via: make MULTI=true.

[pierreguillot]

Done ! Thanks