[Spice-devel] [PATCH] Avoid to access data before a NULL check

[Christophe Fergeau]

On Wed, May 25, 2016 at 11:31:13AM +0100, Frediano Ziglio wrote:
> If you are testing for NULL data this means that variable could be
> NULL so avoid to access before the check to make sure the check is hit.
> 
> Signed-off-by: Frediano Ziglio <fziglio at redhat.com>
> ---
>  server/cursor-channel.c  |  5 +++--
>  server/dcc-send.c        |  6 ++++--
>  server/dcc.c             |  2 +-
>  server/display-channel.c |  6 +++---
>  server/sound.c           | 24 +++++++++++++-----------
>  server/stream.c          |  3 ++-
>  6 files changed, 26 insertions(+), 20 deletions(-)
> 
> diff --git a/server/cursor-channel.c b/server/cursor-channel.c
> index ab6864c..e91aac8 100644
> --- a/server/cursor-channel.c
> +++ b/server/cursor-channel.c
> @@ -227,12 +227,13 @@ static void cursor_channel_client_on_disconnect(RedChannelClient *rcc)
>  static void red_marshall_cursor_init(RedChannelClient *rcc, SpiceMarshaller *base_marshaller,
>                                       RedPipeItem *pipe_item)
>  {
> +    spice_assert(rcc);
> +
>      CursorChannel *cursor_channel;
>      CursorChannelClient *ccc = RCC_TO_CCC(rcc);
>      SpiceMsgCursorInit msg;
>      AddBufInfo info;
>  
> -    spice_assert(rcc);

I'd prefer

CursorChannelClient *ccc;

spice_assert(rcc);
ccc = RCC_TO_CCC(rcc);

ie keep the declaration grouped at the beginning of the block.

An additional comment is that some of the changes in here are candidates
for SPICE_UPCAST, which would make sense to be NULL-safe, so the code
could stay as is.

I was also wondering why we have macros with cryptic names rather than
actual accessors when doing non-upcast? Ie why DCC_TO_WORKER/DCC_TO_DC
rather than red_display_channel_client_get_channel()? (or even
red_channel_client_get_channel() if this makes sense inheritance-wise)


Christophe
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