The types.h header

#include "/package/prog/prjlibs/include/types.h"
{
  type_len    len=str_len("foo");
  type_bool   empty=(len==0);
  type_fd     fd=open("path", O_RDONLY);
  type_status status=fcntl(fd, F_SETFD, FD_CLOEXEC);
  type_error  error=errno;
  type_signal sig=SIGTERM;
}

The types.h C header file defines meaningful aliases for commonly used types.