slacktopic.pl: avoid race condition with multiple instances.

1 files changed, 15 insertions, 6 deletions

diff --git a/slacktopic.pl b/slacktopic.pl
index 78a7b5c..5091e3e 100644
--- a/slacktopic.pl
+++ b/slacktopic.pl
@@ -80,7 +80,7 @@ our %IRSSI = (
 
 # TODO: make some or all of these config variables into irssi
 # settings? Probably overkill, this script is niche-market (probably
-# nobody but the author will ever run it...)
+# nobody but the author and one other person will ever run it...)
 
 # Print verbose debugging messages in local irssi window?
 our $DEBUG = 0;
@@ -94,11 +94,11 @@ our $FAKE = 0;
 # the plain http URL, not https (which doesn't even exist). Actually,
 # ftp would also work, but then you got the whole passive vs. active
 # firewall mess.
-# 20190920 bkw: old URL quit working:
-#our $changelog_url =
-	#"http://ftp.slackware.com/pub/slackware/slackware64-14.2/ChangeLog.txt";
+# Note: ftp.osuosl.org really is the primary Slackware site, but it
+# resolves to 3 different IPs (currently), which seem not to always
+# be in sync with each other.
 our $changelog_url =
-	"ftp://ftp.osuosl.org/pub/slackware/slackware-15.0/ChangeLog.txt";
+	"http://ftp.osuosl.org/pub/slackware/slackware-15.0/ChangeLog.txt";
 
 # Max time curl will spend trying to do its thing. It'll give up after
 # this many seconds, if it can't download the ChangeLog.
@@ -314,11 +314,20 @@ sub set_topic_date {
 	# Get old topic, replace the date with the new one.
 	debugmsg("set_topic_date() called, \$new_date is: $new_date");
 	my $t = $chan->{topic};
-	unless($t =~ s,\[\d\d\d\d-\d\d-\d\d\],[$new_date],) {
+	unless($t =~ s,\[(\d\d\d\d-\d\d-\d\d)\],[$new_date],) {
 		errmsg("topic doesn't contain [yyyy-mm-dd] date, fix it manually");
 		return;
 	}
 
+	# 20230804 bkw: to avoid 2 instances of this script fighting each other when
+	# they're using different mirrors (where one mirror hasn't yet updated but
+	# the other one has), make sure $new_date actually is new.
+	my $topic_date = $1;
+	if($new_date lt $topic_date) {
+		debugmsg("new_date $new_date is older than topic_date $topic_date, ignoring");
+		return;
+	}
+
 	# Don't do anything if the topic's already correct.
 	if($t eq $chan->{topic}) {
 		debugmsg("topic already correct, not doing anything");