vfpSafeWrite
if (vfpSafeWrite(a_dstFd, buf, (size_t)n) != n) {
extern ssize_t vfpSafeWrite(int a_fildes, void *a_buf, size_t a_nbyte);
result = vfpSafeWrite(fd, a_vfp->_vfpStart, len);