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From 8e9756f3cf0d03e5ca43f5212e3d4245ad1d9a00 Mon Sep 17 00:00:00 2001
From: Alexander Scheel <alexander.m.scheel@gmail.com>
Date: Thu, 14 Sep 2017 11:16:42 -0500
Subject: [PATCH] Fix handling of non-EPOLLIN/EPOLLOUT events
Signed-off-by: Alexander Scheel <alexander.m.scheel@gmail.com>
Reviewed-by: Robbie Harwood <rharwood@redhat.com>
Merges: #213
(cherry picked from commit b8f5b2f75612a11753cf742ee0477b98df8e6b02)
---
proxy/src/client/gpm_common.c | 49 ++++++++++++++++++++++++++++++-------------
1 file changed, 35 insertions(+), 14 deletions(-)
diff --git a/proxy/src/client/gpm_common.c b/proxy/src/client/gpm_common.c
index 7d1158e..b14e846 100644
--- a/proxy/src/client/gpm_common.c
+++ b/proxy/src/client/gpm_common.c
@@ -283,26 +283,47 @@ static int gpm_epoll_wait(struct gpm_ctx *gpmctx, uint32_t event_flags) {
gpm_epoll_close(gpmctx);
} else if (epoll_ret == 1 && events[0].data.fd == gpmctx->timerfd) {
/* Got an event which is only our timer */
- ret = read(gpmctx->timerfd, &timer_read, sizeof(uint64_t));
- if (ret == -1 && errno != EAGAIN && errno != EWOULDBLOCK) {
- /* In the case when reading from the timer failed, don't hide the
- * timer error behind ETIMEDOUT such that it isn't retried */
- ret = errno;
+ if ((events[0].events & EPOLLIN) == 0) {
+ /* We got an event which was not EPOLLIN; assume this is an error,
+ * and exit with EBADF: epoll_wait said timerfd had an event,
+ * but that event is not an EPOLIN event. */
+ ret = EBADF;
} else {
- /* If ret == 0, then we definitely timed out. Else, if ret == -1
- * and errno == EAGAIN or errno == EWOULDBLOCK, we're in a weird
- * edge case where epoll thinks the timer can be read, but it
- * is blocking more; treat it like a TIMEOUT and retry, as
- * nothing around us would handle EAGAIN from timer and retry
- * it. */
- ret = ETIMEDOUT;
+ ret = read(gpmctx->timerfd, &timer_read, sizeof(uint64_t));
+ if (ret == -1 && errno != EAGAIN && errno != EWOULDBLOCK) {
+ /* In the case when reading from the timer failed, don't hide the
+ * timer error behind ETIMEDOUT such that it isn't retried */
+ ret = errno;
+ } else {
+ /* If ret == 0, then we definitely timed out. Else, if ret == -1
+ * and errno == EAGAIN or errno == EWOULDBLOCK, we're in a weird
+ * edge case where epoll thinks the timer can be read, but it
+ * is blocking more; treat it like a TIMEOUT and retry, as
+ * nothing around us would handle EAGAIN from timer and retry
+ * it. */
+ ret = ETIMEDOUT;
+ }
}
gpm_epoll_close(gpmctx);
} else {
/* If ret == 2, then we ignore the timerfd; that way if the next
* operation cannot be performed immediately, we timeout and retry.
- * If ret == 1 and data.fd == gpmctx->fd, return 0. */
- ret = 0;
+ * Always check the returned event of the socket fd. */
+ int fd_index = 0;
+ if (epoll_ret == 2 && events[fd_index].data.fd != gpmctx->fd) {
+ fd_index = 1;
+ }
+
+ if ((events[fd_index].events & event_flags) == 0) {
+ /* We cannot call EPOLLIN/EPOLLOUT at this time; assume that this
+ * is a fatal error; return with EBADFD to distinguish from
+ * EBADF in timer_fd case. */
+ ret = EBADFD;
+ gpm_epoll_close(gpmctx);
+ } else {
+ /* We definintely got a EPOLLIN/EPOLLOUT event; return success. */
+ ret = 0;
+ }
}
epoll_ret = epoll_ctl(gpmctx->epollfd, EPOLL_CTL_DEL, gpmctx->fd, NULL);