selftests/hid: Add initial hidraw tests skeleton

Largely inspired from hid_bpf.c for the fixture setup.

Create a couple of tests for hidraw:
- create a uhid device and check if the fixture is working properly
- inject one uhid event and read it through hidraw

These tests are not that useful for now, but will be once we start adding
the ioctl and BPFs to revoke the hidraw node.

Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Link: https://patch.msgid.link/20240827-hidraw-revoke-v5-3-d004a7451aea@kernel.org
Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>

tools/testing/selftests/hid/.gitignore

@@ -2,4 +2,5 @@ bpftool
 *.skel.h
 /tools
 hid_bpf
+hidraw
 results

tools/testing/selftests/hid/Makefile

@@ -32,7 +32,7 @@ CFLAGS += -Wno-unused-command-line-argument
 endif
 
 # Order correspond to 'make run_tests' order
-TEST_GEN_PROGS = hid_bpf
+TEST_GEN_PROGS = hid_bpf hidraw
 
 # Emit succinct information message describing current building step
 # $1 - generic step name (e.g., CC, LINK, etc);

tools/testing/selftests/hid/hidraw.c

@@ -0,0 +1,90 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2022-2024 Red Hat */
+
+#include "hid_common.h"
+
+FIXTURE(hidraw) {
+	int dev_id;
+	int uhid_fd;
+	int hidraw_fd;
+	int hid_id;
+	pthread_t tid;
+};
+static void close_hidraw(FIXTURE_DATA(hidraw) * self)
+{
+	if (self->hidraw_fd)
+		close(self->hidraw_fd);
+	self->hidraw_fd = 0;
+}
+
+FIXTURE_TEARDOWN(hidraw) {
+	void *uhid_err;
+
+	uhid_destroy(_metadata, self->uhid_fd);
+
+	close_hidraw(self);
+	pthread_join(self->tid, &uhid_err);
+}
+#define TEARDOWN_LOG(fmt, ...) do { \
+	TH_LOG(fmt, ##__VA_ARGS__); \
+	hidraw_teardown(_metadata, self, variant); \
+} while (0)
+
+FIXTURE_SETUP(hidraw)
+{
+	time_t t;
+	int err;
+
+	/* initialize random number generator */
+	srand((unsigned int)time(&t));
+
+	self->dev_id = rand() % 1024;
+
+	self->uhid_fd = setup_uhid(_metadata, self->dev_id);
+
+	/* locate the uev, self, variant);ent file of the created device */
+	self->hid_id = get_hid_id(self->dev_id);
+	ASSERT_GT(self->hid_id, 0)
+		TEARDOWN_LOG("Could not locate uhid device id: %d", self->hid_id);
+
+	err = uhid_start_listener(_metadata, &self->tid, self->uhid_fd);
+	ASSERT_EQ(0, err) TEARDOWN_LOG("could not start udev listener: %d", err);
+
+	self->hidraw_fd = open_hidraw(self->dev_id);
+	ASSERT_GE(self->hidraw_fd, 0) TH_LOG("open_hidraw");
+}
+
+/*
+ * A simple test to see if the fixture is working fine.
+ * If this fails, none of the other tests will pass.
+ */
+TEST_F(hidraw, test_create_uhid)
+{
+}
+
+/*
+ * Inject one event in the uhid device,
+ * check that we get the same data through hidraw
+ */
+TEST_F(hidraw, raw_event)
+{
+	__u8 buf[10] = {0};
+	int err;
+
+	/* inject one event */
+	buf[0] = 1;
+	buf[1] = 42;
+	uhid_send_event(_metadata, self->uhid_fd, buf, 6);
+
+	/* read the data from hidraw */
+	memset(buf, 0, sizeof(buf));
+	err = read(self->hidraw_fd, buf, sizeof(buf));
+	ASSERT_EQ(err, 6) TH_LOG("read_hidraw");
+	ASSERT_EQ(buf[0], 1);
+	ASSERT_EQ(buf[1], 42);
+}
+
+int main(int argc, char **argv)
+{
+	return test_harness_run(argc, argv);
+}