Re: [PATCH 1/2] packet: Avoid shadowing index(3)

[Stefano Brivio <sbrivio@redhat.com>]

On Fri, 15 Sep 2023 16:43:36 +1000
David Gibson <david@gibson.dropbear.id.au> wrote:

> A classic gotcha of the standard C library is that its unwise to call any
> variable 'index' because it will shadow the standard string library
> function index(3).  This can cause warnings from cppcheck amongst others,
> and it also means that if the variable is removed you tend to get confusing
> type errors (or sometimes nothing at all) instead of a nice simple "name is
> not defined" error.
> 
> Strictly speaking this only occurs if <string.h> is included, but that is
> so common that as a rule it's best to just avoid it always.  We have a few
> places in packet.[ch] which hit this trap so rename the variables to avoid
> it.
> 
> Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> ---
>  packet.c | 28 ++++++++++++++--------------
>  packet.h | 10 +++++-----
>  2 files changed, 19 insertions(+), 19 deletions(-)
> 
> diff --git a/packet.c b/packet.c
> index ce807e2..8e3a87c 100644
> --- a/packet.c
> +++ b/packet.c
> @@ -33,11 +33,11 @@
>  void packet_add_do(struct pool *p, size_t len, const char *start,
>  		   const char *func, int line)
>  {
> -	size_t index = p->count;
> +	size_t idx = p->count;
>  
> -	if (index >= p->size) {
> +	if (idx >= p->size) {
>  		trace("add packet index %lu to pool with size %lu, %s:%i",
> -		      index, p->size, func, line);
> +		      idx, p->size, func, line);
>  		return;
>  	}
>  
> @@ -66,8 +66,8 @@ void packet_add_do(struct pool *p, size_t len, const char *start,
>  	}
>  #endif
>  
> -	p->pkt[index].offset = start - p->buf;
> -	p->pkt[index].len = len;
> +	p->pkt[idx].offset = start - p->buf;
> +	p->pkt[idx].len = len;
>  
>  	p->count++;
>  }
> @@ -84,13 +84,13 @@ void packet_add_do(struct pool *p, size_t len, const char *start,
>   *
>   * Return: pointer to start of data range, NULL on invalid range or descriptor
>   */
> -void *packet_get_do(const struct pool *p, size_t index, size_t offset,
> +void *packet_get_do(const struct pool *p, size_t idx, size_t offset,

Really minor, but... the comment about @index should be updated as well.

-- 
Stefano