[Libguestfs] [PATCH libnbd 4/4] lib: Add CALL_CALLBACK macro.

[Eric Blake]

On 8/13/19 5:37 PM, Richard W.M. Jones wrote:
> Another simple internal macro, this time encapsulating calling a
> callback.
> ---
>  generator/states-reply-simple.c     |  8 ++++----
>  generator/states-reply-structured.c | 31 ++++++++++++++---------------
>  generator/states-reply.c            |  2 +-
>  generator/states.c                  |  2 +-
>  lib/debug.c                         |  2 +-
>  lib/internal.h                      |  4 ++++
>  6 files changed, 26 insertions(+), 23 deletions(-)
> 
> diff --git a/generator/states-reply-simple.c b/generator/states-reply-simple.c
> index 8905367..8e3d7f1 100644
> --- a/generator/states-reply-simple.c
> +++ b/generator/states-reply-simple.c
> @@ -64,10 +64,10 @@
>        int error = 0;
>  
>        assert (cmd->error == 0);
> -      if (cmd->cb.fn.chunk.callback (cmd->cb.fn.chunk.user_data,
> -                                     cmd->data, cmd->count,
> -                                     cmd->offset, LIBNBD_READ_DATA,
> -                                     &error) == -1)
> +      if (CALL_CALLBACK (cmd->cb.fn.chunk,
> +                         cmd->data, cmd->count,
> +                         cmd->offset, LIBNBD_READ_DATA,
> +                         &error) == -1)

Reduces line length, and we have lots of call sites; this one is
actually more useful than 3 if we're going for ease of typing of a
common pattern.


> +++ b/lib/internal.h
> @@ -273,6 +273,10 @@ struct command {
>    uint32_t error; /* Local errno value */
>  };
>  
> +/* Call a callback. */
> +#define CALL_CALLBACK(cb, ...) \
> +  (cb).callback ((cb).user_data, ##__VA_ARGS__)

And this one doesn't risk any nasty type-punning issues.

ACK

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org

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