slacktopic.pl: only change topic if the update is a security fix

1 files changed, 51 insertions, 2 deletions

diff --git a/slacktopic.pl b/slacktopic.pl
index e45d094..4471584 100644
--- a/slacktopic.pl
+++ b/slacktopic.pl
@@ -13,8 +13,11 @@
 #   and extract the new date from it.
 # - Extract the old date from the current /topic.
 # - If the /topic has an old date, and if it's different from the new
-#   date, update the /topic (really, get ChanServ to do it). Only the date
-#   (inside []) is changed, all the other stuff is left as-is.
+#   date, retrieve the full ChangeLog entry (up to the first "+----..." line),
+#   check for the string "(* Security fix *)" or similar. If nothing
+#   found, it's not a security update, so don't update the topic.
+# - If it needs updating, update the /topic (really, get ChanServ to do # it).
+#   Only the date (inside []) is changed, all the other stuff is left as-is.
 
 # Assumptions made:
 # - Every new ChangeLog entry is a security fix. This is almost
@@ -286,6 +289,9 @@ sub finish_update {
 		return;
 	}
 
+	# Make sure this is a security fix update.
+	return unless is_security_update();
+
 	# Ask ChanServ to change the topic for us. We don't need +o in
 	# the channel, so long as we're logged in to services and have +t.
 	logmsg("ChangeLog updated [$new_date], asking ChanServ to update topic");
@@ -319,5 +325,48 @@ sub exec_update {
 			0); # last arg is unused
 }
 
+# Return true if the first ChangeLog entry is a security update. Unlike
+# the regular check-for-update that happens periodically, this one blocks
+# for up to $cmd_timeout seconds. The updates only happen every few days,
+# I don't see this as a real problem that needs extra complexity to solve.
+sub is_security_update {
+	debugmsg("is_security_update() called");
+
+	my $result = 0;
+	my $lines = 0;
+
+	# Too bad we couldn't have kept the TCP connection open
+	# from the previous run of curl.
+	open my $pipe,
+		"curl --silent --no-buffer --max-time $cmd_timeout $changelog_url|";
+
+	# Read lines until we hit "(* Security fix *)" or the separator that
+	# ends the entry. Unfortunately, even with --no-buffer, we get a lot
+	# more data than we need (no harm done, just wastes a bit of bandwidth).
+	while(<$pipe>) {
+		$lines++;
+
+		# Allow Pat some typos (case insensitive, variable spacing).
+		if(/\(\*\s*security\s+fix\s*\*\)/i) {
+			$result = 1;
+			last;
+		} elsif(/^\+-+\+/) { # Separator between entries.
+			last;
+		}
+	}
+
+	my $curl_exit = (close $pipe) >> 8;
+
+	# 23 is "error writing output" (from curl man page), this is expected
+	# when we close the read pipe. If we get any other error, it's worth
+	# complaining about.
+	if($curl_exit != 23) {
+		errmsg("curl exited with unexpected status: $curl_exit");
+	}
+
+	debugmsg("read $lines lines from ChangeLog, returning $result");
+	return $result;
+}
+
 ### main()
 init();