Add fchmodat2_02 test

This test verifies that fchmodat2() syscall properly raises errors with
invalid arguments.

Reviewed-by: Petr Vorel <pvorel@suse.cz>
Signed-off-by: Andrea Cervesato <andrea.cervesato@suse.com>

runtest/syscalls

@@ -271,6 +271,7 @@ fchmodat01 fchmodat01
 fchmodat02 fchmodat02
 
 fchmodat2_01 fchmodat2_01
+fchmodat2_02 fchmodat2_02
 
 fchown01 fchown01
 fchown01_16 fchown01_16

testcases/kernel/syscalls/fchmodat2/.gitignore

@@ -1 +1,2 @@
 fchmodat2_01
+fchmodat2_02

testcases/kernel/syscalls/fchmodat2/fchmodat2_02.c

@@ -0,0 +1,68 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2024 SUSE LLC Andrea Cervesato <andrea.cervesato@suse.com>
+ */
+
+/*\
+ * [Description]
+ *
+ * This test verifies that fchmodat2() syscall properly raises errors with
+ * invalid values.
+ */
+
+#include "tst_test.h"
+#include "lapi/fcntl.h"
+#include "lapi/syscalls.h"
+#include "tst_tmpdir.h"
+
+#define FILENAME "file.bin"
+
+static char *tmpdir;
+static int fd;
+static int fd_invalid = -1;
+
+static struct tcase {
+	int *fd;
+	char *fname;
+	int mode;
+	int flag;
+	int exp_errno;
+	char *msg;
+} tcases[] = {
+	{&fd_invalid, FILENAME, 0777, 0, EBADF, "bad file descriptor"},
+	{&fd, "doesnt_exist.txt", 0777, 0, ENOENT, "unexisting file"},
+	{&fd, FILENAME, 0777, -1, EINVAL, "invalid flags"},
+};
+
+static void run(unsigned int i)
+{
+	struct tcase *tc = &tcases[i];
+
+	TST_EXP_FAIL(tst_syscall(__NR_fchmodat2,
+		*tc->fd, tc->fname, tc->mode, tc->flag),
+		tc->exp_errno,
+		"Test %s", tc->msg);
+}
+
+static void setup(void)
+{
+	tmpdir = tst_tmpdir_path();
+
+	SAFE_TOUCH(FILENAME, 0640, NULL);
+	fd = SAFE_OPEN(tmpdir, O_PATH | O_DIRECTORY, 0640);
+}
+
+static void cleanup(void)
+{
+	if (fd != -1)
+		SAFE_CLOSE(fd);
+}
+
+static struct tst_test test = {
+	.test = run,
+	.tcnt = ARRAY_SIZE(tcases),
+	.setup = setup,
+	.cleanup = cleanup,
+	.needs_tmpdir = 1,
+};
+