selftest: af_unix: Add zero-buffer test for msg_oob.c

The previous patches fixed two issues related to zero-length
buffer with MSG_PEEK for MSG_OOB skb.

Let's add corresponding tests in msg_oob.c.

Without this series:

  # FAILED: 50 / 60 tests passed.
  # Totals: pass:50 fail:10 xfail:0 xpass:0 skip:0 error:0

With this series:

  # PASSED: 60 / 60 tests passed.
  # Totals: pass:60 fail:0 xfail:0 xpass:0 skip:0 error:0

Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260902202202.892676-4-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 67 insertions, 0 deletions

diff --git a/tools/testing/selftests/net/af_unix/msg_oob.c b/tools/testing/selftests/net/af_unix/msg_oob.c
index 1b499d56656c..f051d79f7a8e 100644
--- a/tools/testing/selftests/net/af_unix/msg_oob.c
+++ b/tools/testing/selftests/net/af_unix/msg_oob.c
@@ -290,6 +290,25 @@ static void __setinlinepair(struct __test_metadata *_metadata,
 	}
 }
 
+static void __setblockingpair(struct __test_metadata *_metadata,
+			      FIXTURE_DATA(msg_oob) *self)
+{
+	int i;
+
+	for (i = 0; i < 2; i++) {
+		int ret, old_flags, flags;
+
+		old_flags = fcntl(self->fd[i * 2 + 1], F_GETFL, 0);
+		ASSERT_NE(-1, old_flags);
+
+		ret = fcntl(self->fd[i * 2 + 1], F_SETFL, old_flags & ~O_NONBLOCK);
+		ASSERT_EQ(0, ret);
+
+		flags = fcntl(self->fd[i * 2 + 1], F_GETFL, 0);
+		ASSERT_EQ(old_flags & ~O_NONBLOCK, flags);
+	}
+}
+
 static void __siocatmarkpair(struct __test_metadata *_metadata,
 			     FIXTURE_DATA(msg_oob) *self,
 			     bool oob_head)
@@ -347,6 +366,9 @@ static void __resetpair(struct __test_metadata *_metadata,
 #define setinlinepair()							\
 	__setinlinepair(_metadata, self)
 
+#define setblockingpair()						\
+	__setblockingpair(_metadata, self)
+
 #define resetpair(reset)						\
 	__resetpair(_metadata, self, variant, reset)
 
@@ -888,4 +910,49 @@ TEST_F(msg_oob, inline_ex_oob_siocatmark)
 	resetpair(true);
 }
 
+TEST_F(msg_oob, zero_buf_oob)
+{
+	sendpair("a", 1, MSG_OOB);
+	recvpair("", 0, 0, 0);
+}
+
+TEST_F(msg_oob, zero_buf_oob_blocking)
+{
+	sendpair("a", 1, MSG_OOB);
+	setblockingpair();
+	recvpair("", 0, 0, 0);
+}
+
+TEST_F(msg_oob, zero_buf_non_oob_oob)
+{
+	sendpair("ab", 2, MSG_OOB);
+	recvpair("", 0, 0, 0);
+}
+
+TEST_F(msg_oob, zero_buf_non_oob_oob_blocking)
+{
+	sendpair("ab", 2, MSG_OOB);
+	setblockingpair();
+	recvpair("", 0, 0, 0);
+}
+
+TEST_F(msg_oob, zero_buf_ex_oob_oob)
+{
+	sendpair("a", 1, MSG_OOB);
+	recvpair("a", 1, 1, MSG_OOB);
+
+	sendpair("b", 1, MSG_OOB);
+	recvpair("", 0, 0, 0);
+}
+
+TEST_F(msg_oob, zero_buf_ex_oob_oob_blocking)
+{
+	sendpair("a", 1, MSG_OOB);
+	recvpair("a", 1, 1, MSG_OOB);
+
+	sendpair("b", 1, MSG_OOB);
+	setblockingpair();
+	recvpair("", 0, 0, 0);
+}
+
 TEST_HARNESS_MAIN