Security: The realpath() calls malloc() and free() is not called (memory leak).

Security: The realpath() calls malloc() and free() is not called (memory leak).

I change the code and didn't realize that realpath() conditionally calls malloc().
When I change th code to pass a variable initialized to 0, I ended up triggering realpath() to call malloc().
This results in a memory leak.

Instead, pass a statically allocated array.