# HG changeset patch
# User Matthew Wild <mwild1@gmail.com>
# Date 1779721359 -3600
# Node ID 6fb6e383123fd4fe4db238c862b460ebde030068
# Parent  573ac422ca1d3f6e290aeaecea7bec92b520cf94
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.

diff -r 573ac422ca1d -r 6fb6e383123f util-src/signal.c
--- a/util-src/signal.c	Mon May 25 15:23:48 2026 +0100
+++ b/util-src/signal.c	Mon May 25 16:02:39 2026 +0100
@@ -498,9 +498,10 @@
 		return 1;
 	}
 
-	for(int i = signalfd_num; i > 0; i--) {
+	for(int i = signalfd_num - 1; i >= 0; i--) {
 		if(signalfds[i].fd == sfd->fd) {
-			signalfds[i] = signalfds[signalfd_num--];
+			signalfds[i] = signalfds[--signalfd_num];
+			break;
 		}
 	}