test: deflake test-cluster-shared-handle-bind-privileged-port

PR-URL: #55378
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Gireesh Punathil <[email protected]>
Reviewed-By: Luigi Pinca <[email protected]>
Reviewed-By: Antoine du Hamel <[email protected]>

test/parallel/test-cluster-shared-handle-bind-privileged-port.js

@@ -35,6 +35,22 @@ if (common.isWindows)
 if (process.getuid() === 0)
   common.skip('as this test should not be run as `root`');
 
+// Some systems won't have port 42 set as a privileged port, in that
+// case, skip the test.
+if (common.isLinux) {
+  const { readFileSync } = require('fs');
+
+  try {
+    const unprivilegedPortStart = parseInt(readFileSync('/proc/sys/net/ipv4/ip_unprivileged_port_start'));
+    if (unprivilegedPortStart <= 42) {
+      common.skip('Port 42 is unprivileged');
+    }
+  } catch {
+    // Do nothing, feature doesn't exist, minimum is 1024 so 42 is usable.
+    // Continue...
+  }
+}
+
 const assert = require('assert');
 const cluster = require('cluster');
 const net = require('net');