[PATCH v1 net-next 03/13] selftest: sysctl: Add test for flock(LOCK_MAND).

[Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>]

This patch adds test cases for LOCK_MAND:

  - LOCK_MAND with/without LOCK_READ/LOCK_WRITE
  - read/write
    - same fd
    - different fd
      - same PID
      - different PID

Signed-off-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
---
 tools/testing/selftests/sysctl/.gitignore     |   2 +
 tools/testing/selftests/sysctl/Makefile       |   9 +-
 tools/testing/selftests/sysctl/sysctl_flock.c | 157 ++++++++++++++++++
 3 files changed, 163 insertions(+), 5 deletions(-)
 create mode 100644 tools/testing/selftests/sysctl/.gitignore
 create mode 100644 tools/testing/selftests/sysctl/sysctl_flock.c

diff --git a/tools/testing/selftests/sysctl/.gitignore b/tools/testing/selftests/sysctl/.gitignore
new file mode 100644
index 000000000000..a3382ba798a6
--- /dev/null
+++ b/tools/testing/selftests/sysctl/.gitignore
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+/sysctl_flock
diff --git a/tools/testing/selftests/sysctl/Makefile b/tools/testing/selftests/sysctl/Makefile
index 110301f9f5be..eb565b6c8340 100644
--- a/tools/testing/selftests/sysctl/Makefile
+++ b/tools/testing/selftests/sysctl/Makefile
@@ -2,12 +2,11 @@
 # Makefile for sysctl selftests.
 # Expects kernel.sysctl_writes_strict=1.
 
-# No binaries, but make sure arg-less "make" doesn't trigger "run_tests".
-all:
+CFLAGS =  -Wall -Wl,--no-as-needed -O2 -g
+CFLAGS += -D_GNU_SOURCE
 
 TEST_PROGS := sysctl.sh
 
-include ../lib.mk
+TEST_GEN_PROGS += sysctl_flock
 
-# Nothing to clean up.
-clean:
+include ../lib.mk
diff --git a/tools/testing/selftests/sysctl/sysctl_flock.c b/tools/testing/selftests/sysctl/sysctl_flock.c
new file mode 100644
index 000000000000..4c4be10ae0d3
--- /dev/null
+++ b/tools/testing/selftests/sysctl/sysctl_flock.c
@@ -0,0 +1,157 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright Amazon.com Inc. or its affiliates. */
+
+#include <unistd.h>
+#include <sys/file.h>
+#include <sys/types.h>
+
+#include "../kselftest_harness.h"
+
+#define SYSCTL_PATH	"/proc/sys/net/ipv4/tcp_migrate_req"
+#define SYSCTL_BUFLEN	8
+
+FIXTURE(proc_sysctl_flock)
+{
+	int fd;
+	char buf[SYSCTL_BUFLEN];
+	int len;
+};
+
+FIXTURE_VARIANT(proc_sysctl_flock)
+{
+	int cmd;
+};
+
+FIXTURE_VARIANT_ADD(proc_sysctl_flock, lock_mand)
+{
+	.cmd = LOCK_MAND,
+};
+
+FIXTURE_VARIANT_ADD(proc_sysctl_flock, lock_mand_read)
+{
+	.cmd = LOCK_MAND | LOCK_READ,
+};
+
+FIXTURE_VARIANT_ADD(proc_sysctl_flock, lock_mand_write)
+{
+	.cmd = LOCK_MAND | LOCK_WRITE,
+};
+
+FIXTURE_VARIANT_ADD(proc_sysctl_flock, lock_mand_read_write)
+{
+	.cmd = LOCK_MAND | LOCK_READ | LOCK_WRITE,
+};
+
+int proc_sysctl_open(struct __test_metadata *_metadata)
+{
+	int fd;
+
+	fd = open(SYSCTL_PATH, O_RDWR);
+	ASSERT_NE(-1, fd);
+
+	return fd;
+}
+
+FIXTURE_SETUP(proc_sysctl_flock)
+{
+	self->fd = proc_sysctl_open(_metadata);
+	ASSERT_EQ(0, flock(self->fd, variant->cmd));
+
+	self->len = read(self->fd, self->buf, sizeof(self->buf));
+	ASSERT_NE(-1, self->len);
+
+	ASSERT_EQ(self->len, write(self->fd, self->buf, self->len));
+}
+
+FIXTURE_TEARDOWN(proc_sysctl_flock)
+{
+	flock(self->fd, LOCK_UN);
+	close(self->fd);
+}
+
+int is_readable(int cmd)
+{
+	return cmd & LOCK_READ;
+}
+
+int is_writable(int cmd)
+{
+	return cmd & LOCK_WRITE;
+}
+
+void proc_sysctl_newfd_read(struct __test_metadata *_metadata,
+			    FIXTURE_DATA(proc_sysctl_flock) *self,
+			    const FIXTURE_VARIANT(proc_sysctl_flock) *variant)
+{
+	char buf[SYSCTL_BUFLEN];
+	int err, fd;
+
+	fd = proc_sysctl_open(_metadata);
+
+	err = read(fd, buf, SYSCTL_BUFLEN);
+	if (is_readable(variant->cmd)) {
+		ASSERT_EQ(self->len, err);
+	} else {
+		ASSERT_EQ(-1, err);
+	}
+
+	close(fd);
+}
+
+void proc_sysctl_newfd_write(struct __test_metadata *_metadata,
+			     FIXTURE_DATA(proc_sysctl_flock) *self,
+			     const FIXTURE_VARIANT(proc_sysctl_flock) *variant)
+{
+	int err, fd;
+
+	fd = proc_sysctl_open(_metadata);
+
+	err = write(fd, self->buf, self->len);
+	if (is_writable(variant->cmd)) {
+		ASSERT_EQ(self->len, err);
+	} else {
+		ASSERT_EQ(-1, err);
+	}
+
+	close(fd);
+}
+
+void proc_sysctl_fork(struct __test_metadata *_metadata,
+		      FIXTURE_DATA(proc_sysctl_flock) *self,
+		      const FIXTURE_VARIANT(proc_sysctl_flock) *variant,
+		      int read)
+{
+	int pid, status;
+
+	pid = fork();
+	if (pid == 0) {
+		if (read)
+			return proc_sysctl_newfd_read(_metadata, self, variant);
+		else
+			return proc_sysctl_newfd_write(_metadata, self, variant);
+	}
+
+	waitpid(pid, &status, 0);
+}
+
+TEST_F(proc_sysctl_flock, test_newfd_read)
+{
+	proc_sysctl_newfd_read(_metadata, self, variant);
+}
+
+TEST_F(proc_sysctl_flock, test_newfd_write)
+{
+	proc_sysctl_newfd_write(_metadata, self, variant);
+}
+
+TEST_F(proc_sysctl_flock, test_fork_newfd_read)
+{
+	proc_sysctl_fork(_metadata, self, variant, 1);
+}
+
+TEST_F(proc_sysctl_flock, test_fork_newfd_write)
+{
+	proc_sysctl_fork(_metadata, self, variant, 0);
+}
+
+TEST_HARNESS_MAIN
-- 
2.30.2