meson.build: check for SYS_pidfd_open

config.h.meson

@@ -475,6 +475,7 @@
 #mesondefine HAVE_MEMFD_CREATE
 #mesondefine HAVE_GETRANDOM
 #mesondefine HAVE_SIGABBREV_NP
+#mesondefine HAVE_PIDFD_OPEN
 
 #mesondefine PIPEWIRE_VERSION_MAJOR
 #mesondefine PIPEWIRE_VERSION_MINOR

meson.build

@@ -282,6 +282,10 @@ if cc.has_function('sigabbrev_np', prefix : '#include <string.h>', args : [ '-D_
   cdata.set('HAVE_SIGABBREV_NP', 1)
 endif
 
+if cc.get_define('SYS_pidfd_open', prefix : '#include <syscall.h>') != ''
+  cdata.set('HAVE_PIDFD_OPEN', 1)
+endif
+
 systemd = dependency('systemd', required: get_option('systemd'))
 systemd_dep = dependency('libsystemd',required: get_option('systemd'))
 if systemd.found() and systemd_dep.found()

test/pwtest.c

@@ -812,7 +812,11 @@ static int monitor_test_forked(struct pwtest_test *t, pid_t pid, int read_fds[_F
 	size_t nevents = 0;
 	int r;
 
+#if HAVE_PIDFD_OPEN
 	pidfd = syscall(SYS_pidfd_open, pid, 0);
+#else
+	errno = ENOSYS;
+#endif
 	/* If we don't have pidfd, we use a timerfd to ping us every 20ms */
 	if (pidfd < 0 && errno == ENOSYS) {
 		pidfd = timerfd_create(CLOCK_MONOTONIC, TFD_NONBLOCK);