On 2023 May 05 (Fri) at 16:13:01 +1000 (+1000), Mark Jamsek wrote:
:On 23-05-04 05:40PM, Todd C. Miller wrote:
:> On Thu, 04 May 2023 21:41:26 -0000, Klemens Nanni wrote:
:>
:> > On Thu, May 04, 2023 at 03:30:30PM -0600, Todd C. Miller wrote:
:> > > This fixes two issues with the parsing of random values:
:> > >
:> > > 1) A random value with a step is now rejected. For example:
:> > >
:> > > ~/10 * * * * echo invalid
:> >
:> > I've ben using ~/10 to randomly distribute four similar tasks so that
:> > they don't start at the same time.
:> >
:> > Is that wrong?
:>
:> I'm fairly certain that doesn't do what you think it does. When I
:> tested it "~/10" behaved the same as "~". The step value is not
:> even parsed.
:
I really dislike "previously accepted (even if behaved differently)"
configs being rejected ...
:todd is correct in that the step value is not parsed with "~/10". We
:recently discovered this when setting up Got mirrors to sync every 15
:minutes. IIRC, Lucas (or op?) asked about syncing each mirror at
:a different 15 minute interval by using the same syntax kn is using.
:
:I found kn's attempted syntax intuitive though; it feels like a natural
:extension of the existing random and step syntax. I also assumed ~/15
:would run every 15 minutes starting with a random minute, and since
:discovering it didn't work like that, I've been carrying a simple patch
:that allows kn's syntax:
:
: ~/15 random 15 minute intervals in [0, 59]
: 1~9/10 random 10 minute intervals in [1,59]
:
... but I really like this syntax and behaviour.
I haven't had a chance to review the code, but I think this would be a
better direction for us to go.
-peter
:----8<--------
:diff refs/remotes/origin/master refs/heads/master
:commit - e253a7cc21de530da6fcf49c1279258fecade8f4
:commit + 761b09ae46431344766330cc14c958ffca5a3a0a
:blob - ab683b8476a8c862aabc53101b4080959820835a
:blob + 030ab599dcf07eb3e94efe90c118e4e9bea8f6c4
:--- usr.sbin/cron/entry.c
:+++ usr.sbin/cron/entry.c
:@@ -456,10 +456,11 @@ get_range(bitstr_t *bits, int low, int high, const cha
: /* range = number | number* "~" number* | number "-" number ["/" number]
: */
:
:- int i, num1, num2, num3;
:+ int i, num1, num2, num3, rndstep;
:
: num1 = low;
: num2 = high;
:+ rndstep = 0;
:
: if (ch == '*') {
: /* '*' means [low, high] but can still be modified by /step
:@@ -497,7 +498,7 @@ get_range(bitstr_t *bits, int low, int high, const cha
:
: /* get the (optional) number following the tilde
: */
:- ch = get_number(&num2, low, names, ch, file, ", \t\n");
:+ ch = get_number(&num2, low, names, ch, file, "/, \t\n");
: if (ch == EOF)
: ch = get_char(file);
: if (ch == EOF || num1 > num2) {
:@@ -509,6 +510,10 @@ get_range(bitstr_t *bits, int low, int high, const cha
: */
: num3 = num1;
: num1 = arc4random_uniform(num2 - num3 + 1) + num3;
:+ if (ch == '/') {
:+ rndstep = 1;
:+ break;
:+ }
: /* FALLTHROUGH */
: default:
: /* not a range, it's a single number.
:@@ -538,6 +543,10 @@ get_range(bitstr_t *bits, int low, int high, const cha
: ch = get_number(&num3, 0, NULL, ch, file, ", \t\n");
: if (ch == EOF || num3 == 0)
: return (EOF);
:+ if (rndstep) {
:+ num1 %= num3;
:+ num2 = high;
:+ }
: } else {
: /* no step. default==1.
: */
:-------->8----
:
:> It sounds like what you want is the proposed syntax "*/~10"
:> to use a random offset.
:
:But this would be nice too! Anything that enables regular intervals from
:a random offset would satisfy a common enough use case.
:
:--
:Mark Jamsek <fnc.bsdbox.org|got.bsdbox.org>
:GPG: F2FF 13DE 6A06 C471 CA80 E6E2 2930 DC66 86EE CF68
--
Time flies like an arrow, but fruit flies like a banana.
