This is the fix for bug https://github.com/php/php-src/issues/24695 as
integrated into PHP 8.4, 8.5, and 8.6 branches, found in pull request
https://github.com/php/php-src/pull/24698

Without this patch, if a test case in sapi/fpm/tests fails to start
php-fpm, it can run 'kill -USR2 0' which sends that signal to all
processes in the current process group including the test-runner,
prematurely aborting the test run.

We hit this bug on illumos because the regression test
bug80024-socket-reduced-inherit.phpt depends on the "ondemand"
process manager which needs edge-triggered event handling, which is
only implemented for the kqueue and epoll modules but not from the
event-port module sapi/fpm/fpm/events/port.c which is (for good
reasons) preferred over epoll when available.

From 810ce5e5f6e4bc64a01f998e30fd4c9418289e2c Mon Sep 17 00:00:00 2001
From: Lazizbek Ergashev <lazerg2@gmail.com>
Date: Tue, 27 Oct 2026 14:12:06 +0500
Subject: [PATCH] Fix GH-24695: FPM tester sends signal to process group when
 PID is missing (#24698)

When FPM fails to start, getPid() reports the missing PID file and
returns 0, and signal() then runs kill -USR2 0. That signals the whole
process group and takes down run-tests.php along with the test. Now
signal() returns early in that case, so the test just fails and the run
keeps going.

Co-authored-by: Bill Sommerfeld <sommerfeld@hamachi.org>
---
 sapi/fpm/tests/tester.inc | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/sapi/fpm/tests/tester.inc b/sapi/fpm/tests/tester.inc
index 8e67d17430a6..c98252292489 100644
--- a/sapi/fpm/tests/tester.inc
+++ b/sapi/fpm/tests/tester.inc
@@ -1119,6 +1119,9 @@ class Tester
     {
         if (is_null($pid)) {
             $pid = $this->getPid();
+            if ($pid === 0) {
+                return '';
+            }
         }
         $cmd = "kill -$signal $pid";
         $this->trace('Sending signal using command', $cmd, true);