the @code{tv_sec} argument to be 0, and don't necessarily handle all
file permissions in the manner required by POSIX:
Linux kernel 2.6.25.
+@item
+When using @code{UTIME_OMIT} for the modification time, but specifying
+an access time, some systems fail to update the change time:
+Linux kernel 2.6.32.
@end itemize
Portability problems not fixed by Gnulib: