On 12 jan. 2012, at 17:48, Matthew Story wrote:
> On Thu, Jan 12, 2012 at 3:15 AM, Dirk-Willem van Gulik <di...@webweaving.org>
> wrote:
> [...snip]
> # If ${hostid_file} already exists, we take UUID from there.
> - if [ -r ${hostid_file} ]; then
> + # If ${hostid_file} already exists, we take UUID from there. We use
> + # a -f rather than a -r check as the histid_file may in fact be
> + # a symbolic link.
>
> per the test man-page, `-r' tests for readability, regardless of type, and
> `-f' tests for the existence of a regular file. `-r' does include an
> implicit test for existence, so `-r' will in fact work for symlinks, and fail
> reliably if the symlink source_file does not exist (relevant bits from the
> test man-page at the bottom of this message):
….
> with this patch, if ${hostid_file} exists, and is non-readable, cat
> ${hostid_file} will fail, and yield no $1 to hostid_set (effectively
> identical to a hostid_file that is empty). this is not the desired behavior:
Totally understood - but wanted to stay close to the behavior of
dhclient-script as I understand it. And this happens to also make the behavior
of /etc/rc.d/sshd on first run the same. Keep in mind that one can always set
the rc variable.
...
> This line is actually why you are seeing a hostid_file on restart. The
> hostid_file does not exist on your system, and per the comment, and
> implementation, if a hostid_file does not exist, one is generated and set via
> sysctl (via the hostid_set function).
Agreed - as _set is better.
> There is a small race condition in this file (unless rc.d is doing some
> locking on hostid_file in the caller)
….
Right - which in this case is one we should not worry about - this is during
boot - as the rc.d files are ran one by one; and generally not twice. However -
the lock issue does affect /sbin/dhclient-script - and I've seen this
behaviour there in the wild.
Dw_______________________________________________
freebsd-bugs@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-bugs
To unsubscribe, send any mail to "freebsd-bugs-unsubscr...@freebsd.org"
