diff --git a/src/libutil/monitor-fd.hh b/src/libutil/monitor-fd.hh index 5ee0b88ef..9518cf8aa 100644 --- a/src/libutil/monitor-fd.hh +++ b/src/libutil/monitor-fd.hh @@ -22,27 +22,38 @@ public: { thread = std::thread([fd]() { while (true) { - /* Wait indefinitely until a POLLHUP occurs. */ - struct pollfd fds[1]; - fds[0].fd = fd; - /* This shouldn't be necessary, but macOS doesn't seem to - like a zeroed out events field. - See rdar://37537852. - */ - fds[0].events = POLLHUP; - auto count = poll(fds, 1, -1); - if (count == -1) abort(); // can't happen - /* This shouldn't happen, but can on macOS due to a bug. - See rdar://37550628. + /* Wait indefinitely until a POLLHUP occurs. */ + struct pollfd fds[1]; + fds[0].fd = fd; + /* Polling for no specific events (i.e. just waiting + for an error/hangup) doesn't work on macOS + anymore. So wait for read events and ignore + them. */ + fds[0].events = + #ifdef __APPLE__ + POLLRDNORM + #else + 0 + #endif + ; + auto count = poll(fds, 1, -1); + if (count == -1) abort(); // can't happen + /* This shouldn't happen, but can on macOS due to a bug. + See rdar://37550628. - This may eventually need a delay or further - coordination with the main thread if spinning proves - too harmful. - */ - if (count == 0) continue; - assert(fds[0].revents & POLLHUP); - triggerInterrupt(); - break; + This may eventually need a delay or further + coordination with the main thread if spinning proves + too harmful. + */ + if (count == 0) continue; + if (fds[0].revents & POLLHUP) { + triggerInterrupt(); + break; + } + /* This will only happen on macOS. We sleep a bit to + avoid waking up too often if the client is sending + input. */ + sleep(1); } }); };