[LTP] [PATCH 2/2] syscalls: Add test for splicing to /dev/zero and /dev/null

[Cyril Hrubis]

Both of these devices discard written data.

Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
---
 runtest/syscalls                            |  1 +
 testcases/kernel/syscalls/splice/.gitignore |  1 +
 testcases/kernel/syscalls/splice/splice09.c | 55 +++++++++++++++++++++
 3 files changed, 57 insertions(+)
 create mode 100644 testcases/kernel/syscalls/splice/splice09.c

diff --git a/runtest/syscalls b/runtest/syscalls
index 0889f58a1..50bc350f0 100644
--- a/runtest/syscalls
+++ b/runtest/syscalls
@@ -1518,6 +1518,7 @@ splice05 splice05
 splice06 splice06
 splice07 splice07
 splice08 splice08
+splice09 splice09
 
 tee01 tee01
 tee02 tee02
diff --git a/testcases/kernel/syscalls/splice/.gitignore b/testcases/kernel/syscalls/splice/.gitignore
index 9453cf93a..96b1727a1 100644
--- a/testcases/kernel/syscalls/splice/.gitignore
+++ b/testcases/kernel/syscalls/splice/.gitignore
@@ -6,3 +6,4 @@
 /splice06
 /splice07
 /splice08
+/splice09
diff --git a/testcases/kernel/syscalls/splice/splice09.c b/testcases/kernel/syscalls/splice/splice09.c
new file mode 100644
index 000000000..46f755b01
--- /dev/null
+++ b/testcases/kernel/syscalls/splice/splice09.c
@@ -0,0 +1,55 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2024 Cyril Hrubis <chrubis@suse.cz>
+ */
+
+/*\
+ * [Description]
+ *
+ * Test for splicing to /dev/zero and /dev/null these two devices discard all
+ * data written to them.
+ *
+ * The support for splicing to /dev/zero was added in:
+ * 1b057bd800c3 ("drivers/char/mem: implement splice() for /dev/zero, /dev/full")
+ */
+
+#define _GNU_SOURCE
+#include "tst_test.h"
+
+static const char *test_devices[] = {
+	"/dev/null",
+	"/dev/zero",
+};
+
+static void verify_splice(unsigned int n)
+{
+	char buf[1024];
+	char dev_fd;
+	int pipefd[2];
+
+	memset(buf, 0xff, sizeof(buf));
+
+	tst_res(TINFO, "Testing %s", test_devices[n]);
+
+	dev_fd = SAFE_OPEN(test_devices[n], O_WRONLY);
+
+	SAFE_PIPE(pipefd);
+	SAFE_WRITE(1, pipefd[1], buf, sizeof(buf));
+
+	TST_EXP_POSITIVE(splice(pipefd[0], NULL, dev_fd, NULL, sizeof(buf), 0));
+
+	if (TST_PASS && TST_RET != sizeof(buf))
+		tst_res(TFAIL, "Wrote only part of the pipe buffer");
+	else
+		tst_res(TPASS, "Wrote whole pipe buffer");
+
+	SAFE_CLOSE(pipefd[0]);
+	SAFE_CLOSE(pipefd[1]);
+	SAFE_CLOSE(dev_fd);
+}
+
+static struct tst_test test = {
+	.test = verify_splice,
+	.tcnt = ARRAY_SIZE(test_devices),
+	.min_kver = "6.7",
+};
-- 
2.43.2