[lxc-devel] [PATCH] Invoke lxc_map_ids only when id_map is not empty

[Serge Hallyn]

Quoting Alexander Vladimirov (alexander.idkfa.vladimirov at gmail.com):
> 
> Signed-off-by: Alexander Vladimirov <alexander.idkfa.vladimirov at gmail.com>

Nothing wrong with this, but why do you want this?  It will save you
a 4096k allocation (which we could optimize away so it only happens
if needed), and one function call, but that is all...  Is there more
that I'm missing?

(In general I do prefer to keep the caller shorter and easier to read
if we can)

> ---
>  src/lxc/start.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/src/lxc/start.c b/src/lxc/start.c
> index 3fdfa04..05646c2 100644
> --- a/src/lxc/start.c
> +++ b/src/lxc/start.c
> @@ -823,9 +823,11 @@ int lxc_spawn(struct lxc_handler *handler)
>  	 * call doesn't change anything immediately, but allows the
>  	 * container to setuid(0) (0 being mapped to something else on
>  	 * the host) later to become a valid uid again */
> -	if (lxc_map_ids(&handler->conf->id_map, handler->pid)) {
> -		ERROR("failed to set up id mapping");
> -		goto out_delete_net;
> +	if (!lxc_list_empty(&handler->conf->id_map)) {
> +		if (lxc_map_ids(&handler->conf->id_map, handler->pid)) {
> +			ERROR("failed to set up id mapping");
> +			goto out_delete_net;
> +		}
>  	}
>  
>  	/* Tell the child to continue its initialization.  we'll get
> -- 
> 1.8.1.5
> 
> 
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