[LTP] [PATCH v2] syscalls/unshare: New test: CLONE_NEWNS unshares fs info

[Cyril Hrubis]

Hi!
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (c) 2025 lufei <lufei@uniontech.com>
> + */
> +
> +/*\
> + * This test case is to verify unshare(CLONE_NEWNS) also unshares filesystem
> + * information.
> + *
> + */
> +
> +#define _GNU_SOURCE
> +
> +#include "tst_test.h"
> +#include "lapi/sched.h"
> +
> +#define TMP "/tmp1"
> +
> +static char *cwd;
> +static char *tmpdir;
> +static char *c_cwd;
> +static char *p_cwd;
> +static size_t size = 1024;
> +
> +static void setup(void)
> +{
> +	cwd = SAFE_MALLOC(size);
> +	SAFE_GETCWD(cwd, size);
> +
> +	tmpdir = tst_tmpdir_genpath(TMP);
> +	SAFE_MKDIR(tmpdir, 0700);

There no need for absolute paths, the test starts with CWD pointing to
the newly created temporary directory. So all that we need to do is to
use relative paths with:

#define TESTDIR "test_dir"

	SAFE_MKDIR(TESTDIR, 0700);

And then later do SAFE_CHDIR(TESTDIR) in the child.

> +	c_cwd = SAFE_MALLOC(size);
> +	p_cwd = SAFE_MALLOC(size);

We do not need two of these, we can use the same buffer both in child
and parent.

> +}
> +
> +static void cleanup(void)
> +{
> +	free(c_cwd);
> +	free(p_cwd);
> +	free(cwd);
> +}
> +
> +
> +static void run(void)
> +{
> +	struct tst_clone_args args = {
> +		.flags = CLONE_FS,
> +		.exit_signal = SIGCHLD,
> +	};
> +
> +	if (!SAFE_CLONE(&args)) {
> +
> +		TST_EXP_PASS(unshare(CLONE_NEWNS));
> +
> +		SAFE_CHDIR(tmpdir);
> +		SAFE_GETCWD(c_cwd, size);
> +
> +		if (strcmp(cwd, c_cwd) == 0)
> +			tst_res(TFAIL, "current dir not changed");
> +		else
> +			tst_res(TPASS, "current dir changed to %s", c_cwd);
> +	} else {
> +		SAFE_WAIT(NULL);
> +
> +		SAFE_GETCWD(p_cwd, size);
> +
> +		if (strcmp(cwd, p_cwd) == 0)
> +			tst_res(TPASS, "cwd unshared");
> +		else
> +			tst_res(TFAIL, "cwd not unshare as expected");
                                                  ^
						unshared
> +	}
> +}
> +
> +static struct tst_test test = {
> +	.forks_child = 1,
> +	.needs_root = 1,
> +	.needs_tmpdir = 1,
> +	.test_all = run,
> +	.setup = setup,
> +	.cleanup = cleanup,
> +};
> -- 
> 2.39.3
> 

-- 
Cyril Hrubis
chrubis@suse.cz