From: Junio C Hamano <gitster@pobox.com>
Date: Mon, 26 Feb 2024 17:49:02 GMT
Subject: Re: [PATCH] upload-pack: don't send null character in abort message to the client
Message-ID: <xmqqttlvnmk1.fsf@gitster.g>
In-Reply-To: <20240225183452.1939334-1-szeder.dev@gmail.com>

SZEDER Gábor <szeder.dev@gmail.com> writes:

> Since 583b7ea31b (upload-pack/fetch-pack: support side-band
> communication, 2006-06-21) the abort message sent by upload-pack in
> case of possible repository corruption ends with a null character.

It is so so old that makes me wonder if it is safe to "fix" it, but
I cannot think of a sensible way to write a third-party client that
may have been working fine and would break when this fix is made.

> This can be seen in several test cases in 't5530-upload-pack-error.sh'
> where 'grep <pattern> output.err' often reports "Binary file
> output.err matches" because of that null character.
>
> The reason for this is that the abort message is defined as a string
> literal, and we pass its size to the send function as
> sizeof(abort_msg), which also counts the terminating null character.
>
> Use strlen() instead to avoid sending that terminating null character.
>
> Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
> ---
>  upload-pack.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/upload-pack.c b/upload-pack.c
> index 2537affa90..6e0d441ef5 100644
> --- a/upload-pack.c
> +++ b/upload-pack.c
> @@ -463,7 +463,7 @@ static void create_pack_file(struct upload_pack_data *pack_data,
>  
>   fail:
>  	free(output_state);
> -	send_client_data(3, abort_msg, sizeof(abort_msg),
> +	send_client_data(3, abort_msg, strlen(abort_msg),
>  			 pack_data->use_sideband);
>  	die("git upload-pack: %s", abort_msg);
>  }