1. Why do I get a conflicting types error for function xyz(), when compiling the POSIX model?

The error that you get happens because there is a mismatch between the header declaration of the POSIX call in your OS, and the definition in the Cloud9 POSIX model.

Unfortunately, the POSIX model is not fully independent of the host OS, as it references several system headers. In case you get such errors, you have to manually tweak the POSIX model such that the declarations match the header definitions. The good news is that the headers usually differ only in minor ways (e.g., a parameter type is "int" instead of "long"), so the fix should be straightforward.