From a1d42a6ce0398da3833bedf374ef2571af7fea50 Mon Sep 17 00:00:00 2001 From: Damien Miller Date: Fri, 14 Jan 2022 13:49:32 +1100 Subject: [PATCH] fix edge case in poll(2) wrapper Correct handling of select(2) exceptfds. These should only be consulted for POLLPRI flagged pfds and not unconditionally converted to POLLERR. with and ok dtucker@ --- openbsd-compat/bsd-poll.c | 23 +++++++++-------------- 1 file changed, 9 insertions(+), 14 deletions(-) diff --git a/openbsd-compat/bsd-poll.c b/openbsd-compat/bsd-poll.c index 8084776ce..f8b427fc7 100644 --- a/openbsd-compat/bsd-poll.c +++ b/openbsd-compat/bsd-poll.c @@ -33,8 +33,8 @@ /* * A minimal implementation of ppoll(2), built on top of pselect(2). * - * Only supports POLLIN and POLLOUT flags in pfd.events, and POLLIN, POLLOUT - * and POLLERR flags in revents. + * Only supports POLLIN, POLLOUT and POLLPRI flags in pfd.events and + * revents. Notably POLLERR, POLLHUP and POLLNVAL are not supported. * * Supports pfd.fd = -1 meaning "unused" although it's not standard. */ @@ -71,14 +71,12 @@ ppoll(struct pollfd *fds, nfds_t nfds, const struct timespec *tmoutp, fd = fds[i].fd; if (fd == -1) continue; - if (fds[i].events & POLLIN) { + if (fds[i].events & POLLIN) FD_SET(fd, readfds); - FD_SET(fd, exceptfds); - } - if (fds[i].events & POLLOUT) { + if (fds[i].events & POLLOUT) FD_SET(fd, writefds); + if (fds[i].events & POLLPRI) FD_SET(fd, exceptfds); - } } ret = pselect(maxfd + 1, readfds, writefds, exceptfds, tmoutp, sigmask); @@ -90,15 +88,12 @@ 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 (FD_ISSET(fd, readfds)) fds[i].revents |= POLLIN; - } - if (FD_ISSET(fd, writefds)) { + if (FD_ISSET(fd, writefds)) fds[i].revents |= POLLOUT; - } - if (FD_ISSET(fd, exceptfds)) { - fds[i].revents |= POLLERR; - } + if (FD_ISSET(fd, exceptfds)) + fds[i].revents |= POLLPRI; } out: