Re: [PATCH] Clear fd after closing to avoid double-close error

From: Duy Nguyen <pclouds@gmail.com>
Date: Oct 22, 2013, 12:39 UTC
Message-ID: <CACsJy8DtvaojrrQr4=uYCRse7N+SXb+WdjY+C_0FRSjYsNC6zg@mail.gmail.com>
In-Reply-To: <1382443823-31317-1-git-send-email-jl@opera.com>

On Tue, Oct 22, 2013 at 7:10 PM, Jens Lindström <jl@opera.com> wrote:

Show 9 quoted lines

> From: Jens Lindstrom <jl@opera.com>
>
> In send_pack(), clear the fd passed to pack_objects() by setting
> it to -1, since pack_objects() closes the fd (via a call to
> run_command()).
>
> Not doing so risks having git_transport_push(), caller of
> send_pack(), closing the fd again, possibly incorrectly closing
> some other open file.

Not your itch. But if you have time you may want to fix fetch-pack too. It has the same problem. fetch-pack.c:get_pack() with use_sideband == 0 passes fd[0] to start_command(), then later its caller transport.c:fetch_refs_via_pack() closes the handle again.

Show 12 quoted lines

> Signed-off-by: Jens Lindström <jl@opera.com>
> ---
>  send-pack.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/send-pack.c b/send-pack.c
> index 7d172ef..7def2af 100644
> --- a/send-pack.c
> +++ b/send-pack.c
> @@ -302,6 +302,9 @@ int send_pack(struct send_pack_args *args,
>                                 finish_async(&demux);
>                         return -1;

In this code block, there is "close(out);", we may need to set fd[1] = -1 too.

Show 7 quoted lines

>                 }
> +               if (!args->stateless_rpc)
> +                       /* Closed by pack_objects() via start_command() */
> +                       fd[1] = -1;
>         }
>         if (args->stateless_rpc && cmds_sent)
>                 packet_flush(out);

I was puzzled by this packet_flush(out) for a while because I thought "out" was already closed. Turns out when stateless_rpc is true, a new pipe is created in pack_objects() and "out" is not closed. So everything is still good (and messy).

Life would have been simpler if fd[1] was _always_ closed by send_pack(), like in c20181e (start_command(), if .in/.out > 0, closes file descriptors, not the callers - 2008-02-21).

-- 
Duy