Re: [PATCH 1/2] tools: use memcpy instead of strncpy in getBridge

[Jürgen Groß <jgross@xxxxxxxx>]

On 05.10.20 18:02, Bertrand Marquis wrote:
> Use memcpy in getBridge to prevent gcc warnings about truncated
> strings. We know that we might truncate it, so the gcc warning
> here is wrong.
> Revert previous change changing buffer sizes as bigger buffers
> are not needed.
>
> Signed-off-by: Bertrand Marquis <bertrand.marquis@xxxxxxx>
> ---
>   tools/libs/stat/xenstat_linux.c | 9 +++++++--
>   1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/tools/libs/stat/xenstat_linux.c b/tools/libs/stat/xenstat_linux.c
> index d2ee6fda64..1db35c604c 100644
> --- a/tools/libs/stat/xenstat_linux.c
> +++ b/tools/libs/stat/xenstat_linux.c
> @@ -78,7 +78,12 @@ static void getBridge(char *excludeName, char *result, 
> size_t resultLen)
>                                 sprintf(tmp, "/sys/class/net/%s/bridge", 
> de->d_name);
>   
>   				if (access(tmp, F_OK) == 0) {
> -                                       strncpy(result, de->d_name, resultLen);
> +                                       /*
> +                                        * Do not use strncpy to prevent 
> compiler warning with
> +                                        * gcc >= 10.0
> +                                        * If de->d_name is longer then 
> resultLen we truncate it
> +                                        */
> +                                       memcpy(result, de->d_name, resultLen - 
> 1);
I think you want min(NAME_MAX, resultLen - 1) for the length.


Juergen