Only return events from ppoll that were requested.

If the underlying system's select() returns bits that were not in the
request set, our ppoll() implementation can return revents for events
not requested, which can apparently cause a hang.  Only return revents
for activity in the requested event set.  bz#3416, analysis and fix by
yaroslav.kuzmin at vmssoftware com, ok djm@

diff --git a/openbsd-compat/bsd-poll.c b/openbsd-compat/bsd-poll.c
index 781ee978a651c150ec754ca7d82aa38a6dfbb9ee..9a9794f5863be1509765a9f7c6e1cc9a936444df 100644 (file)
--- a/openbsd-compat/bsd-poll.c
+++ b/openbsd-compat/bsd-poll.c
@@ -91,11 +91,11 @@ ppoll(struct pollfd *fds, nfds_t nfds, const struct timespec *tmoutp,
                fds[i].revents = 0;
                if (fd == -1)
                        continue;
-               if (FD_ISSET(fd, readfds))
+               if ((fds[i].events & POLLIN) && FD_ISSET(fd, readfds))
                        fds[i].revents |= POLLIN;
-               if (FD_ISSET(fd, writefds))
+               if ((fds[i].events & POLLOUT) && FD_ISSET(fd, writefds))
                        fds[i].revents |= POLLOUT;
-               if (FD_ISSET(fd, exceptfds))
+               if ((fds[i].events & POLLPRI) && FD_ISSET(fd, exceptfds))
                        fds[i].revents |= POLLPRI;
        }