util.signal: Fix signalfd closure on non-Linux systems The loop was incorrect for 0-indexed arrays. It started at signalfd_num, which is the total number of signalfds, and decremented to 1 (condition was >0). So if 1 signalfd was registered, it would check only signalfds[1]. At capacity (32 signalfds) it would read past the end of the array. In every case, it would always skip the entry at position [0], leading to a leak. The swap-with-tail removal of the matched item used the post-decrement operator, leading to accessing the array slot just beyond the tail. Finally, it didn't break after finding a match. Probably harmless, but there isn't expected to be more than a single entry per fd, as far as I can tell.

-- XEP-0307: Unique Room Names for Multi-User Chat
local st = require "prosody.util.stanza";
local unique_name = require "prosody.util.id".medium;
module:add_feature "http://jabber.org/protocol/muc#unique"
module:hook("iq-get/host/http://jabber.org/protocol/muc#unique:unique", function(event)
	local origin, stanza = event.origin, event.stanza;
	origin.send(st.reply(stanza)
		:tag("unique", {xmlns = "http://jabber.org/protocol/muc#unique"})
		:text(unique_name():lower())
	);
	return true;
end,-1);