[v3,1/5] fs: unicode: Use strscpy() instead of strncpy()

Following warning was reported by Kernel Test Robot.

In function 'utf8_parse_version',
inlined from 'utf8_load' at fs/unicode/utf8mod.c:195:7:
>> fs/unicode/utf8mod.c:175:2: warning: 'strncpy' specified bound 12 equals
destination size [-Wstringop-truncation]
175 |  strncpy(version_string, version, sizeof(version_string));
    |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The -Wstringop-truncation warning highlights the unintended
uses of the strncpy function that truncate the terminating NULL
character from the source string.
Unlike strncpy(), strscpy() always null-terminates the destination string,
hence use strscpy() instead of strncpy().

Fixes: 9d53690f0d4e5 (unicode: implement higher level API for string handling)
Signed-off-by: Shreeya Patel <shreeya.patel@collabora.com>
Reported-by: kernel test robot <lkp@intel.com>
---

Changes in v3
  - Return error if strscpy() returns value < 0

Changes in v2
  - Resolve warning of -Wstringop-truncation reported by
    kernel test robot.

 fs/unicode/utf8-core.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

Shreeya Patel <shreeya.patel@collabora.com> writes:

> Following warning was reported by Kernel Test Robot.
>
> In function 'utf8_parse_version',
> inlined from 'utf8_load' at fs/unicode/utf8mod.c:195:7:
>>> fs/unicode/utf8mod.c:175:2: warning: 'strncpy' specified bound 12 equals
> destination size [-Wstringop-truncation]
> 175 |  strncpy(version_string, version, sizeof(version_string));
>     |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> The -Wstringop-truncation warning highlights the unintended
> uses of the strncpy function that truncate the terminating NULL
> character from the source string.
> Unlike strncpy(), strscpy() always null-terminates the destination string,
> hence use strscpy() instead of strncpy().
>
> Fixes: 9d53690f0d4e5 (unicode: implement higher level API for string handling)
> Signed-off-by: Shreeya Patel <shreeya.patel@collabora.com>
> Reported-by: kernel test robot <lkp@intel.com>
> ---
>
> Changes in v3
>   - Return error if strscpy() returns value < 0
>
> Changes in v2
>   - Resolve warning of -Wstringop-truncation reported by
>     kernel test robot.
>
>  fs/unicode/utf8-core.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>

Hi Shreeya,

Thanks for fixing this.

> diff --git a/fs/unicode/utf8-core.c b/fs/unicode/utf8-core.c
> index dc25823bf..706f086bb 100644
> --- a/fs/unicode/utf8-core.c
> +++ b/fs/unicode/utf8-core.c
> @@ -180,7 +180,10 @@ static int utf8_parse_version(const char *version, unsigned int *maj,
>  		{0, NULL}
>  	};
>  
> -	strncpy(version_string, version, sizeof(version_string));
> +	int ret = strscpy(version_string, version, sizeof(version_string));

Usually, no spaces between variable declarations

Other than that,

Acked-by: Gabriel Krisman Bertazi <krisman@collabora.com>

> +
> +	if (ret < 0)
> +		return ret;
>  	if (match_token(version_string, token, args) != 1)
>  		return -EINVAL;