[LTP] [PATCH] gethostname: Add negative test for gethostname

[Avinesh Kumar]

Hi Yang Xu,
Please see comments below

On Tuesday, April 16, 2024 10:04:14 AM GMT+2 Yang Xu via ltp wrote:
> Add negative cases for gethostname(), when errno is ENAMETOOLONG
> 
> Signed-off-by: Yang Xu <xuyang2018.jy@fujitsu.com>
> ---
>  runtest/syscalls                              |  1 +
>  .../kernel/syscalls/gethostname/.gitignore    |  1 +
>  .../syscalls/gethostname/gethostname02.c      | 41 +++++++++++++++++++
>  3 files changed, 43 insertions(+)
>  create mode 100644 testcases/kernel/syscalls/gethostname/gethostname02.c
> 
> diff --git a/runtest/syscalls b/runtest/syscalls
> index de4f5a633..cc1e39c05 100644
> --- a/runtest/syscalls
> +++ b/runtest/syscalls
> @@ -477,6 +477,7 @@ gethostbyname_r01 gethostbyname_r01
>  gethostid01 gethostid01
> 
>  gethostname01 gethostname01
> +gethostname02 gethostname02
> 
>  getitimer01 getitimer01
>  getitimer02 getitimer02
> diff --git a/testcases/kernel/syscalls/gethostname/.gitignore
> b/testcases/kernel/syscalls/gethostname/.gitignore index
> d09d5d288..d6e4cffcb 100644
> --- a/testcases/kernel/syscalls/gethostname/.gitignore
> +++ b/testcases/kernel/syscalls/gethostname/.gitignore
> @@ -1 +1,2 @@
>  /gethostname01
> +/gethostname02
> diff --git a/testcases/kernel/syscalls/gethostname/gethostname02.c
> b/testcases/kernel/syscalls/gethostname/gethostname02.c new file mode
> 100644
> index 000000000..e9d97d05a
> --- /dev/null
> +++ b/testcases/kernel/syscalls/gethostname/gethostname02.c
> @@ -0,0 +1,41 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (c) 2024 FUJITSU LIMITED. All Rights Reserved.
> + * Author: Yang Xu <xuyang2018.jy@fujitsu.com>
> + */
> +
> +/*\
> + * [Description]
> + *
> + * Verify that gethostname(2) fails with
> + *
> + * - ENAMETOOLONG when len is smaller than the actual size
> + */
> +
> +#include "tst_test.h"
> +
> +static char hostname_enametoolong[100];
> +
> +static struct test_case_t {
> +	char *hostname;
> +	int size;
> +	int expected_errno;
> +	char *desc;
> +} tcases[] = {
> +	{hostname_enametoolong, 1, ENAMETOOLONG,
If I found correctly, minimum possible size for hostname can be just 1 char.
So if we want to test ENAMETOOLONG errno by passing a len value which is not
enough to store the hostname value, maybe one approach can be, first fetch the
hostname value by a successful gethostname() call, and then pass the smaller
len value than the received hostname length to verify this errno scenario.

Also, if we are testing just a single case, imho lets not use the
test_case_t struct.

> +		"len is smaller than the actual size"},
> +};
> +
> +static void verify_gethostname(unsigned int i)
> +{
> +	struct test_case_t *tc = &tcases[i];
> +
> +	TST_EXP_FAIL(gethostname(tc->hostname, sizeof(tc->size)),
I am confused why we have sizeof() here.
> +		tc->expected_errno, "%s", tc->desc);
> +}
> +
> +static struct tst_test test = {
> +	.tcnt = ARRAY_SIZE(tcases),
> +	.test = verify_gethostname,
> +	.needs_root = 1,
I guess root is not required.
> +};

Regards,
Avinesh