commandhelper hangs indefinetely in poll() on macOS on commandtest test2 and later because POLLNVAL is returned on revents for input file descriptor opened from /dev/null, i.e this hangs: $ tests/commandhelper < /dev/null BEGIN STDOUT BEGIN STDERR ^C But it works fine with regular stdin: $ tests/commandhelper <<< test BEGIN STDOUT BEGIN STDERR test test END STDOUT END STDERR The issue is mentioned in poll(2): BUGS The poll() system call currently does not support devices. With the change all 28 cases in commandtest pass. Signed-off-by: Roman Bolshakov <r.bolshakov(a)yadro.com&gt; --- tests/commandhelper.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/tests/commandhelper.c b/tests/commandhelper.c index 7c260c4e13..676ef55e9f 100644 --- a/tests/commandhelper.c +++ b/tests/commandhelper.c @@ -190,7 +190,15 @@ int main(int argc, char **argv) { } for (i = 0; i < numpollfds; i++) { - if (fds[i].revents & (POLLIN | POLLHUP | POLLERR)) { + if (fds[i].revents & (POLLIN | POLLHUP | POLLERR | +# ifdef __APPLE__ + /* + * poll() on /dev/null will return POLLNVAL + */ + POLLNVAL)) { +# else + 0)) { +# endif fds[i].revents = 0; got = read(fds[i].fd, buf, sizeof(buf)); -- 2.28.0