[PATCH weston 2/3] xwm: Make hash_table_lookup use an output parameter

[Pekka Paalanen]

On Tue,  7 Apr 2015 12:12:14 -0500
Derek Foreman <derekf at osg.samsung.com> wrote:

> Previously hash_table_lookup returned a pointer which must always be tested
> for NULL - but rarely was.
> 
> Now hash_table_lookup returns the found data as an out parameter and returns
> an integer indicating whether the lookup succeeded or not.  This lets us
> flag the return value as warn_unused_result so the compiler can stop us from
> missing the test.
> 
> Signed-off-by: Derek Foreman <derekf at osg.samsung.com>
> ---
>  xwayland/hash.c           | 15 +++++++++------
>  xwayland/hash.h           |  6 +++++-
>  xwayland/window-manager.c | 29 ++++++++++++++---------------
>  3 files changed, 28 insertions(+), 22 deletions(-)
> 
> diff --git a/xwayland/hash.c b/xwayland/hash.c
> index 54f3de9..2e5ecfc 100644
> --- a/xwayland/hash.c
> +++ b/xwayland/hash.c
> @@ -201,16 +201,19 @@ hash_table_for_each(struct hash_table *ht,
>  	}
>  }
>  
> -void *
> -hash_table_lookup(struct hash_table *ht, uint32_t hash)
> +int
> +hash_table_lookup(struct hash_table *ht, uint32_t hash,
> +		  struct weston_wm_window **ret)

int for a boolean? ;-)

Apart from that,
Reviewed-by: Pekka Paalanen <pekka.paalanen at collabora.co.uk>

>  {
>  	struct hash_entry *entry;
>  
>  	entry = hash_table_search(ht, hash);
> -	if (entry != NULL)
> -		return entry->data;
> -
> -	return NULL;
> +	if (entry != NULL) {
> +		*ret = entry->data;
> +		return 1;
> +	}
> +	*ret = NULL;
> +	return 0;
>  }
>  
>  static void
> diff --git a/xwayland/hash.h b/xwayland/hash.h
> index 6e1674e..b181f19 100644
> --- a/xwayland/hash.h
> +++ b/xwayland/hash.h
> @@ -36,11 +36,15 @@
>  #define HASH_H
>  
>  struct hash_table;
> +struct weston_wm_window;
>  struct hash_table *hash_table_create(void);
>  typedef void (*hash_table_iterator_func_t)(void *element, void *data);
>  
>  void hash_table_destroy(struct hash_table *ht);
> -void *hash_table_lookup(struct hash_table *ht, uint32_t hash);
> +int hash_table_lookup(struct hash_table *ht, uint32_t hash,
> +		      struct weston_wm_window **ret)
> +					__attribute__ ((warn_unused_result));

I suppose this really isn't used for anything else than
weston_wm_window, so ok for now.


Thanks,
pq