tcpip/transport/tcp: read side only shutdown of an endpoint

Support shutdown on only the read side of an endpoint. Reads performed
after a call to Shutdown with only the ShutdownRead flag will return
ErrClosedForReceive without data.

Break out the shutdown(2) with SHUT_RD syscall test into to two tests.
The first tests that no packets are sent when shutting down the read
side of a socket. The second tests that, after shutting down the read
side of a socket, unread data can still be read, or an EOF if there is
no more data to read.

Change-Id: I9d7c0a06937909cbb466b7591544a4bcaebb11ce
PiperOrigin-RevId: 244459430

1 files changed, 27 insertions, 2 deletions

diff --git a/test/syscalls/linux/socket_ip_tcp_generic.cc b/test/syscalls/linux/socket_ip_tcp_generic.cc
index 8a222008e..2f45f01ec 100644
--- a/test/syscalls/linux/socket_ip_tcp_generic.cc
+++ b/test/syscalls/linux/socket_ip_tcp_generic.cc
@@ -190,8 +190,7 @@ TEST_P(TCPSocketPairTest, FINSentOnShutdownWrWithUnreadData) {
 }
 
 // This test will verify that when data is received by a socket, even if it's
-// not read SHUT_RD will not cause any packets to be generated and data will
-// remain in the buffer and can be read later.
+// not read SHUT_RD will not cause any packets to be generated.
 TEST_P(TCPSocketPairTest, ShutdownRdShouldCauseNoPacketsWithUnreadData) {
   auto sockets = ASSERT_NO_ERRNO_AND_VALUE(NewSocketPair());
 
@@ -213,10 +212,36 @@ TEST_P(TCPSocketPairTest, ShutdownRdShouldCauseNoPacketsWithUnreadData) {
   constexpr int kPollNoResponseTimeoutMs = 3000;
   ASSERT_THAT(RetryEINTR(poll)(&poll_fd2, 1, kPollNoResponseTimeoutMs),
               SyscallSucceedsWithValue(0));  // Timeout.
+}
+
+// This test will verify that a socket which has unread data will still allow
+// the data to be read after shutting down the read side, and once there is no
+// unread data left, then read will return an EOF.
+TEST_P(TCPSocketPairTest, ShutdownRdAllowsReadOfReceivedDataBeforeEOF) {
+  auto sockets = ASSERT_NO_ERRNO_AND_VALUE(NewSocketPair());
+
+  char buf[10] = {};
+  ASSERT_THAT(RetryEINTR(write)(sockets->first_fd(), buf, sizeof(buf)),
+              SyscallSucceedsWithValue(sizeof(buf)));
+
+  // Wait until t_ sees the data on its side but don't read it.
+  struct pollfd poll_fd = {sockets->second_fd(), POLLIN | POLLHUP, 0};
+  constexpr int kPollTimeoutMs = 20000;  // Wait up to 20 seconds for the data.
+  ASSERT_THAT(RetryEINTR(poll)(&poll_fd, 1, kPollTimeoutMs),
+              SyscallSucceedsWithValue(1));
+
+  // Now shutdown the read end.
+  ASSERT_THAT(shutdown(sockets->second_fd(), SHUT_RD), SyscallSucceeds());
 
   // Even though we did a SHUT_RD on the read end we can still read the data.
   ASSERT_THAT(RetryEINTR(read)(sockets->second_fd(), buf, sizeof(buf)),
               SyscallSucceedsWithValue(sizeof(buf)));
+
+  // After reading all of the data, reading the closed read end returns EOF.
+  ASSERT_THAT(RetryEINTR(poll)(&poll_fd, 1, kPollTimeoutMs),
+              SyscallSucceedsWithValue(1));
+  ASSERT_THAT(RetryEINTR(read)(sockets->second_fd(), buf, sizeof(buf)),
+              SyscallSucceedsWithValue(0));
 }
 
 TEST_P(TCPSocketPairTest, ClosedReadNonBlockingSocket) {