Tcl Source Code

Inspecting code, I have doubts about potential crashes from accessing freed encodings in multithreaded environments. Several functions have code similar to below:

if (encoding == NULL) // encoding is passed by caller
   encoding = systemEncoding; // systemEncoding is GLOBAL shared by threads

Do some operations involving the encoding. 

The issue I am wondering about is that the reference count on systemEncoding is not incremented in such cases. What happens if some other thread calls encoding system and changes the systemEncoding causing the original one in use above to be freed?

Need to build a test case to verify above race condition but perhaps someone could corroborate or refute my analysis. And save me the trouble of creating the test case :-)