Force registration for EPOLLHUP, not EPOLLRDHUP, in vfs2's epoll.

Compare Linux's fs/eventpoll.c:do_epoll_ctl(). I don't know where EPOLLRDHUP
came from.

PiperOrigin-RevId: 323874419

1 files changed, 22 insertions, 0 deletions

diff --git a/test/syscalls/linux/epoll.cc b/test/syscalls/linux/epoll.cc
index f57d38dc7..2101e5c9f 100644
--- a/test/syscalls/linux/epoll.cc
+++ b/test/syscalls/linux/epoll.cc
@@ -422,6 +422,28 @@ TEST(EpollTest, CloseFile) {
               SyscallSucceedsWithValue(0));
 }
 
+TEST(EpollTest, PipeReaderHupAfterWriterClosed) {
+  auto epollfd = ASSERT_NO_ERRNO_AND_VALUE(NewEpollFD());
+  int pipefds[2];
+  ASSERT_THAT(pipe(pipefds), SyscallSucceeds());
+  FileDescriptor rfd(pipefds[0]);
+  FileDescriptor wfd(pipefds[1]);
+
+  ASSERT_NO_ERRNO(RegisterEpollFD(epollfd.get(), rfd.get(), 0, kMagicConstant));
+  struct epoll_event result[kFDsPerEpoll];
+  // Initially, rfd should not generate any events of interest.
+  ASSERT_THAT(epoll_wait(epollfd.get(), result, kFDsPerEpoll, 0),
+              SyscallSucceedsWithValue(0));
+  // Close the write end of the pipe.
+  wfd.reset();
+  // rfd should now generate EPOLLHUP, which EPOLL_CTL_ADD unconditionally adds
+  // to the set of events of interest.
+  ASSERT_THAT(epoll_wait(epollfd.get(), result, kFDsPerEpoll, 0),
+              SyscallSucceedsWithValue(1));
+  EXPECT_EQ(result[0].events, EPOLLHUP);
+  EXPECT_EQ(result[0].data.u64, kMagicConstant);
+}
+
 }  // namespace
 
 }  // namespace testing