+/* Avoid recursion with rpl_futimens. */
+#undef futimens
+
+#if HAVE_UTIMENSAT || HAVE_FUTIMENS
+/* Cache variable for whether syscall works; used to avoid calling the
+ syscall if we know it will just fail with ENOSYS. 0 = unknown, 1 =
+ yes, -1 = no. */
+static int utimensat_works_really;
+#endif /* HAVE_UTIMENSAT || HAVE_UTIMENSAT */
+
+/* Validate the requested timestamps. Return 0 if the resulting
+ timespec can be used for utimensat (after possibly modifying it to
+ work around bugs in utimensat). Return 1 if the timespec needs
+ further adjustment based on stat results for utimes or other less
+ powerful interfaces. Return -1, with errno set to EINVAL, if
+ timespec is out of range. */
+static int
+validate_timespec (struct timespec timespec[2])
+{
+ int result = 0;
+ assert (timespec);
+ if ((timespec[0].tv_nsec != UTIME_NOW
+ && timespec[0].tv_nsec != UTIME_OMIT
+ && (timespec[0].tv_nsec < 0 || 1000000000 <= timespec[0].tv_nsec))
+ || (timespec[1].tv_nsec != UTIME_NOW
+ && timespec[1].tv_nsec != UTIME_OMIT
+ && (timespec[1].tv_nsec < 0 || 1000000000 <= timespec[1].tv_nsec)))
+ {
+ errno = EINVAL;
+ return -1;
+ }
+ /* Work around Linux kernel 2.6.25 bug, where utimensat fails with
+ EINVAL if tv_sec is not 0 when using the flag values of
+ tv_nsec. */
+ if (timespec[0].tv_nsec == UTIME_NOW
+ || timespec[0].tv_nsec == UTIME_OMIT)
+ {
+ timespec[0].tv_sec = 0;
+ result = 1;
+ }
+ if (timespec[1].tv_nsec == UTIME_NOW
+ || timespec[1].tv_nsec == UTIME_OMIT)
+ {
+ timespec[1].tv_sec = 0;
+ result = 1;
+ }
+ return result;
+}
+
+/* Normalize any UTIME_NOW or UTIME_OMIT values in *TS, using stat
+ buffer STATBUF to obtain the current timestamps of the file. If
+ both times are UTIME_NOW, set *TS to NULL (as this can avoid some
+ permissions issues). If both times are UTIME_OMIT, return true
+ (nothing further beyond the prior collection of STATBUF is
+ necessary); otherwise return false. */
+static bool
+update_timespec (struct stat const *statbuf, struct timespec *ts[2])
+{
+ struct timespec *timespec = *ts;
+ if (timespec[0].tv_nsec == UTIME_OMIT
+ && timespec[1].tv_nsec == UTIME_OMIT)
+ return true;
+ if (timespec[0].tv_nsec == UTIME_NOW
+ && timespec[1].tv_nsec == UTIME_NOW)
+ {
+ *ts = NULL;
+ return false;
+ }
+
+ if (timespec[0].tv_nsec == UTIME_OMIT)
+ timespec[0] = get_stat_atime (statbuf);
+ else if (timespec[0].tv_nsec == UTIME_NOW)
+ gettime (×pec[0]);
+
+ if (timespec[1].tv_nsec == UTIME_OMIT)
+ timespec[1] = get_stat_mtime (statbuf);
+ else if (timespec[1].tv_nsec == UTIME_NOW)
+ gettime (×pec[1]);
+
+ return false;
+}
+