Add rename15 test

This test has been extracted from symlink01 and it verifies that
rename() is working correctly on symlink() generated files, renaming
symbolic link and checking if stat() information are preserved.

Reviewed-by: Cyril Hrubis <chrubis@suse.cz>
Signed-off-by: Andrea Cervesato <andrea.cervesato@suse.com>

runtest/syscalls

@@ -1196,6 +1196,7 @@ rename11 rename11
 rename12 rename12
 rename13 rename13
 rename14 rename14
+rename15 rename15
 
 #renameat test cases
 renameat01 renameat01

testcases/kernel/syscalls/rename/.gitignore

@@ -11,3 +11,4 @@
 /rename12
 /rename13
 /rename14
+/rename15

testcases/kernel/syscalls/rename/rename15.c

@@ -0,0 +1,131 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2000 Silicon Graphics, Inc.  All Rights Reserved.
+ *    Authors: David Fenner, Jon Hendrickson
+ * Copyright (C) 2024 Andrea Cervesato andrea.cervesato@suse.com
+ */
+
+/*\
+ * [Description]
+ *
+ * This test suite validates the behavior of the `rename()` system call on
+ * symbolic links under three scenarios:
+ *
+ * - rename a symlink pointing to an existing file and verifies that the
+ *   symlink's inode and device number remain unchanged.
+ *
+ * - rename a symlink pointing to a non-existent path, ensuring that the
+ *   original symlink remains unaffected.
+ *
+ * - rename a symlink pointing to a created file, confirming that the new
+ *   symlink points to the correct file.
+ */
+
+#include "tst_test.h"
+#include "tst_tmpdir.h"
+
+#define MNTPOINT "mnt"
+#define OLDNAME MNTPOINT"/msymlink0"
+#define NEWNAME MNTPOINT"/asymlink0"
+#define OBJNAME MNTPOINT"/object"
+
+static char *tmpdir;
+static char *oldname;
+static char *newname;
+static char *objname;
+
+static void test_existing(void)
+{
+	tst_res(TINFO, "Test rename() on symlink pointing to an existent path");
+
+	struct stat buff_stat;
+	struct stat oldsym_stat;
+	struct stat newsym_stat;
+
+	SAFE_SYMLINK(tmpdir, oldname);
+	SAFE_STAT(oldname, &oldsym_stat);
+
+	SAFE_RENAME(oldname, newname);
+
+	TST_EXP_PASS(lstat(newname, &buff_stat));
+	TST_EXP_FAIL(lstat(oldname, &buff_stat), ENOENT);
+
+	SAFE_STAT(newname, &newsym_stat);
+	TST_EXP_EQ_LI(oldsym_stat.st_ino, newsym_stat.st_ino);
+	TST_EXP_EQ_LI(oldsym_stat.st_dev, newsym_stat.st_dev);
+
+	SAFE_UNLINK(newname);
+}
+
+static void test_non_existing(void)
+{
+	tst_res(TINFO, "Test rename() on symlink pointing to a non-existent path");
+
+	struct stat path_stat;
+
+	SAFE_SYMLINK("this_path_doesnt_exist", oldname);
+	TST_EXP_FAIL(stat(oldname, &path_stat), ENOENT);
+	TST_EXP_PASS(lstat(oldname, &path_stat));
+
+	SAFE_RENAME(oldname, newname);
+
+	TST_EXP_FAIL(lstat(oldname, &path_stat), ENOENT);
+	TST_EXP_PASS(lstat(newname, &path_stat));
+	TST_EXP_FAIL(stat(newname, &path_stat), ENOENT);
+
+	SAFE_UNLINK(newname);
+}
+
+static void test_creat(void)
+{
+	tst_res(TINFO, "Test rename() on symlink pointing to a path created lately");
+
+	struct stat path_stat;
+
+	SAFE_SYMLINK(objname, oldname);
+	TST_EXP_FAIL(stat(oldname, &path_stat), ENOENT);
+	TST_EXP_PASS(lstat(oldname, &path_stat));
+
+	tst_res(TINFO, "Create object file");
+
+	int fd;
+
+	fd = SAFE_CREAT(objname, 0700);
+	if (fd >= 0)
+		SAFE_CLOSE(fd);
+
+	SAFE_RENAME(oldname, newname);
+
+	TST_EXP_PASS(lstat(newname, &path_stat));
+	TST_EXP_PASS(stat(newname, &path_stat));
+
+	TST_EXP_FAIL(lstat(oldname, &path_stat), ENOENT);
+	TST_EXP_PASS(stat(objname, &path_stat));
+
+	SAFE_UNLINK(objname);
+	SAFE_UNLINK(newname);
+}
+
+static void run(void)
+{
+	test_existing();
+	test_creat();
+	test_non_existing();
+}
+
+static void setup(void)
+{
+	tmpdir = tst_tmpdir_path();
+	oldname = tst_tmpdir_genpath(OLDNAME);
+	newname = tst_tmpdir_genpath(NEWNAME);
+	objname = tst_tmpdir_genpath(OBJNAME);
+}
+
+static struct tst_test test = {
+	.setup = setup,
+	.test_all = run,
+	.all_filesystems = 1,
+	.mntpoint = MNTPOINT,
+	.format_device = 1,
+	.needs_root = 1,
+};