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fix edge case in poll(2) wrapper

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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@
This commit is contained in:
Damien Miller 2022-01-14 13:49:32 +11:00
parent 976b9588b4
commit a1d42a6ce0
1 changed files with 9 additions and 14 deletions
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23
openbsd-compat/bsd-poll.c
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@ -33,8 +33,8 @@
/* /*
* A minimal implementation of ppoll(2), built on top of pselect(2). * A minimal implementation of ppoll(2), built on top of pselect(2).
* *
* Only supports POLLIN and POLLOUT flags in pfd.events, and POLLIN, POLLOUT * Only supports POLLIN, POLLOUT and POLLPRI flags in pfd.events and
* and POLLERR flags in revents. * revents. Notably POLLERR, POLLHUP and POLLNVAL are not supported.
* *
* Supports pfd.fd = -1 meaning "unused" although it's not standard. * 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; fd = fds[i].fd;
if (fd == -1) if (fd == -1)
continue; continue;
if (fds[i].events & POLLIN) { if (fds[i].events & POLLIN)
FD_SET(fd, readfds); FD_SET(fd, readfds);
FD_SET(fd, exceptfds); if (fds[i].events & POLLOUT)
}
if (fds[i].events & POLLOUT) {
FD_SET(fd, writefds); FD_SET(fd, writefds);
if (fds[i].events & POLLPRI)
FD_SET(fd, exceptfds); FD_SET(fd, exceptfds);
}
} }
ret = pselect(maxfd + 1, readfds, writefds, exceptfds, tmoutp, sigmask); 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; fds[i].revents = 0;
if (fd == -1) if (fd == -1)
continue; continue;
if (FD_ISSET(fd, readfds)) { if (FD_ISSET(fd, readfds))
fds[i].revents |= POLLIN; fds[i].revents |= POLLIN;
} if (FD_ISSET(fd, writefds))
if (FD_ISSET(fd, writefds)) {
fds[i].revents |= POLLOUT; fds[i].revents |= POLLOUT;
} if (FD_ISSET(fd, exceptfds))
if (FD_ISSET(fd, exceptfds)) { fds[i].revents |= POLLPRI;
fds[i].revents |= POLLERR;
}
} }
out: out: