[PATCH 10/22] selftests/pidfd: add first supported_mask test

[Christian Brauner <brauner@kernel.org>]

Verify that when PIDFD_INFO_SUPPORTED_MASK is requested, the kernel
returns the supported_mask field indicating which flags the kernel
supports.

Signed-off-by: Christian Brauner <brauner@kernel.org>
---
 tools/testing/selftests/pidfd/pidfd_info_test.c | 41 +++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/tools/testing/selftests/pidfd/pidfd_info_test.c b/tools/testing/selftests/pidfd/pidfd_info_test.c
index a0eb6e81eaa2..b31a0597fbae 100644
--- a/tools/testing/selftests/pidfd/pidfd_info_test.c
+++ b/tools/testing/selftests/pidfd/pidfd_info_test.c
@@ -690,4 +690,45 @@ TEST_F(pidfd_info, thread_group_exec_thread)
 	EXPECT_EQ(close(pidfd_thread), 0);
 }
 
+/*
+ * Test: PIDFD_INFO_SUPPORTED_MASK field
+ *
+ * Verify that when PIDFD_INFO_SUPPORTED_MASK is requested, the kernel
+ * returns the supported_mask field indicating which flags the kernel supports.
+ */
+TEST(supported_mask_field)
+{
+	struct pidfd_info info = {
+		.mask = PIDFD_INFO_SUPPORTED_MASK,
+	};
+	int pidfd;
+	pid_t pid;
+
+	pid = create_child(&pidfd, 0);
+	ASSERT_GE(pid, 0);
+
+	if (pid == 0)
+		pause();
+
+	/* Request supported_mask field */
+	ASSERT_EQ(ioctl(pidfd, PIDFD_GET_INFO, &info), 0);
+
+	/* Verify PIDFD_INFO_SUPPORTED_MASK is set in the reply */
+	ASSERT_TRUE(!!(info.mask & PIDFD_INFO_SUPPORTED_MASK));
+
+	/* Verify supported_mask contains expected flags */
+	ASSERT_TRUE(!!(info.supported_mask & PIDFD_INFO_PID));
+	ASSERT_TRUE(!!(info.supported_mask & PIDFD_INFO_CREDS));
+	ASSERT_TRUE(!!(info.supported_mask & PIDFD_INFO_CGROUPID));
+	ASSERT_TRUE(!!(info.supported_mask & PIDFD_INFO_EXIT));
+	ASSERT_TRUE(!!(info.supported_mask & PIDFD_INFO_COREDUMP));
+	ASSERT_TRUE(!!(info.supported_mask & PIDFD_INFO_SUPPORTED_MASK));
+	ASSERT_TRUE(!!(info.supported_mask & PIDFD_INFO_COREDUMP_SIGNAL));
+
+	/* Clean up */
+	sys_pidfd_send_signal(pidfd, SIGKILL, NULL, 0);
+	sys_waitid(P_PIDFD, pidfd, NULL, WEXITED);
+	close(pidfd);
+}
+
 TEST_HARNESS_MAIN

-- 
2.47.3