Re: [PATCH] mnl_attr_get_str: document that the result is not NUL-terminated

[Pablo Neira Ayuso <pablo@netfilter.org>]

On Tue, Aug 14, 2012 at 12:19:16PM +0200, Florian Weimer wrote:
> Hi,
>
> while reviewing from libmnl-using code, I discovered that the result
> of mnl_attr_get_str was used as a NUL-terminated string, although in
> reality the string wasn't.  I think this should be mentioned in the
> documentation.

Looking at the kernel:

static inline int nla_put_string(struct sk_buff *skb, int attrtype,
                                 const char *str)
{
        return nla_put(skb, attrtype, strlen(str) + 1, str);
}

It seems it always returns the string plus one byte (that is assumed
to be NULL).

Are you looking at any netlink subsystem in particular? What are you
noticing?

> Florian
> --
> Florian Weimer / Red Hat Product Security Team

> From 1e4b192907eb15f4fbfd581c8c0fa8359aa9439f Mon Sep 17 00:00:00 2001
> From: Florian Weimer <fweimer@redhat.com>
> Date: Tue, 14 Aug 2012 12:16:32 +0200
> Subject: [PATCH] mnl_attr_get_str: document that the result is not
>  NUL-terminated
>
> Signed-off-by: Florian Weimer <fweimer@redhat.com>
> ---
>  src/attr.c |    1 +
>  1 files changed, 1 insertions(+), 0 deletions(-)
>
> diff --git a/src/attr.c b/src/attr.c
> index 1136c50..c890bf2 100644
> --- a/src/attr.c
> +++ b/src/attr.c
> @@ -393,6 +393,7 @@ EXPORT_SYMBOL(mnl_attr_get_u64);
>   * \param attr pointer to netlink attribute
>   *
>   * This function returns the payload of string attribute value.
> + * Note that the string is not necessarily NUL-terminated.
>   */
>  const char *mnl_attr_get_str(const struct nlattr *attr)
>  {
> --
> 1.7.7.6
>