From: Rong Tao
> Sent: 29 October 2022 04:00
>
> From: Rong Tao <rongtao@xxxxxxxx>
>
> Replace strncpy() with strncat(), strncat() leaves the dst string zero
> terminated. Compile samples/bpf warning:
This only makes a difference because tests for strncat() have not been added.
srtncat() really is never the string function you are looking for.
David
>
> $ cd samples/bpf
> $ make
> ...
> In function ‘__enable_controllers’:
> samples/bpf/../../tools/testing/selftests/bpf/cgroup_helpers.c:80:17: warning: ‘strncpy’ specified
> bound 4097 equals destination size [-Wstringop-truncation]
> 80 | strncpy(enable, controllers, sizeof(enable));
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> Signed-off-by: Rong Tao <rongtao@xxxxxxxx>
> ---
> tools/testing/selftests/bpf/cgroup_helpers.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/bpf/cgroup_helpers.c
> b/tools/testing/selftests/bpf/cgroup_helpers.c
> index a70e873b267e..912e6522c7c5 100644
> --- a/tools/testing/selftests/bpf/cgroup_helpers.c
> +++ b/tools/testing/selftests/bpf/cgroup_helpers.c
> @@ -77,7 +77,8 @@ static int __enable_controllers(const char *cgroup_path, const char *controllers
> enable[len] = 0;
> close(fd);
> } else {
> - strncpy(enable, controllers, sizeof(enable) - 1);
> + enable[0] = '\0';
> + strncat(enable, controllers, sizeof(enable) - 1);
> }
>
> snprintf(path, sizeof(path), "%s/cgroup.subtree_control", cgroup_path);
> --
> 2.31.1
-
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