> The behavior is undefined if the calls to functions in this library introduce a file system race, that is, when multiple threads, processes, or computers inte

> The behavior is undefined if the calls to functions in this library introduce a file system race, that is, when multiple threads, processes, or computers interleave access and modification to the same object in a file system. There is a lot to bet that this has been added for portability reasons. The POSIX atomicity guarantees on file operations are not provided on every system. The facts are, when this issue came, it has been treated as it should have been. This is, once again, a sign of mature security processes and behaviour regarding the compiler implementers.