Re: [PATCH ulogd2,v2 3/6] ulogd: raise error on unknown config key

[Florian Westphal <fw@strlen.de>]

Corubba Smith <corubba@gmx.de> wrote:
> Until a6fbeb96e889 ("new configuration file syntax (Magnus Boden)")
> this was already caught, and the enum member is still present.
> 
> Check if the for loop worked throught the whole array without hitting a
> matching config option, and return with the unknown key error code.
> Because there is no existing config_entry struct with that unknwon key
> to use with the established config_errce pointer, allocate a new struct.
> This potentially creates a memory leak if that config_entry is never
> freed again, but for me that is acceptable is this rare case.
> 
> Since the memory allocation for the struct can fail, also reuse the old
> out-of-memory error to indicate that.
> 
> Signed-off-by: Corubba Smith <corubba@gmx.de>
> ---
> Changes in v2:
>   - Reduce indentation of case statements (Florian Westphal)
> 
>  src/conffile.c | 11 +++++++++++
>  src/ulogd.c    |  2 ++
>  2 files changed, 13 insertions(+)
> 
> diff --git a/src/conffile.c b/src/conffile.c
> index cc5552c..7b9fb0f 100644
> --- a/src/conffile.c
> +++ b/src/conffile.c
> @@ -236,6 +236,17 @@ int config_parse_file(const char *section, struct config_keyset *kset)
>  			break;
>  		}
>  		pr_debug("parse_file: exiting main loop\n");
> +
> +		if (i == kset->num_ces) {
> +			config_errce = calloc(1, sizeof(struct config_entry));
> +			if (config_errce == NULL) {
> +				err = -ERROOM;
> +				goto cpf_error;
> +			}
> +			strncpy(&config_errce->key[0], wordbuf, CONFIG_KEY_LEN - 1);

This raises a bogus compiler warning for me:
conffile.c:246:25: warning: '__builtin_strncpy' output may be truncated copying 30 bytes from a string of length 254 [-Wstringop-truncation]
  246 |                         strncpy(config_errce->key, wordbuf, sizeof(config_errce->key));

What do you make of this?

-                       strncpy(&config_errce->key[0], wordbuf, CONFIG_KEY_LEN - 1);
+                       snprintf(config_errce->key, sizeof(config_errce->key), "%s", wordbuf);