No rule without exception ;-). Some very few C code designed to be callable
from Fortran code - of course (it is why I consequently use pointers for the
arguments and why I supply always two versions: with and without underscore
appended to the function names [the most common ways how Fortran compilers
mangle FUNCTION and SUBROUTINE names though there exist few exceptions ...]).

It is some simple timer call (vtime) returning CPU and wall clock time, a more
complicated timer (timing) returning a whole bunch of resource usage data and a
small function for trapping all kind of signals (customize! ;-) to make system
administrators angry (check out whether a time limit for a batch queue is a real
limit - probably not since rather often no SIGKILL is sent but just SIGXCPU :-).