[lttng-dev] [PATCH babeltrace-1.5 6/6] Fix: lttng-live format: do not error out on empty streams hang up

[Jérémie Galarneau]

All patches of this series were merged in stable-1.5.

Thanks!
Jérémie

On Thu, 5 Dec 2019 at 01:58, Mathieu Desnoyers
<mathieu.desnoyers at efficios.com> wrote:
>
> Attaching to a stream hung up before providing any trace packet
> causes ctf_open_mmap_stream_read() to return an error.
>
> This kind of scenario can happen with the upcoming "lttng clear"
> feature.
>
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
> ---
>  formats/ctf/ctf.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/formats/ctf/ctf.c b/formats/ctf/ctf.c
> index 980ebc9a..1ba9017f 100644
> --- a/formats/ctf/ctf.c
> +++ b/formats/ctf/ctf.c
> @@ -2571,8 +2571,13 @@ int ctf_open_mmap_stream_read(struct ctf_trace *td,
>         }
>
>         ret = prepare_mmap_stream_definition(td, file_stream, packet_seek);
> -       if (ret)
> +       if (ret) {
> +               /* We need to check for EOF here for empty files. */
> +               if (unlikely(file_stream->pos.offset == EOF)) {
> +                       ret = 0;
> +               }
>                 goto error_index;
> +       }
>
>         /*
>          * For now, only a single clock per trace is supported.
> --
> 2.17.1
>


-- 
Jérémie Galarneau
EfficiOS Inc.
http://www.efficios.com