Re: [PATCH v1 3/4] builtin/repack.c: change xwrite to write_in_full to allow large sizes.

From: Junio C Hamano <gitster@pobox.com>
Date: Feb 26, 2024, 23:54 UTC
Message-ID: <xmqqwmqqixx9.fsf@gitster.g>
In-Reply-To: <20240226220539.3494-4-randall.becker@nexbridge.ca>

"Randall S. Becker" <the.n.e.key@gmail.com> writes:

Show 6 quoted lines

> From: "Randall S. Becker" <rsbecker@nexbridge.com>
>
> This change is required because some platforms do not support file writes of
> arbitrary sizes (e.g, NonStop). xwrite ends up truncating the output to the
> maximum single I/O size possible for the destination device. The result of
> write_in_full() is also passed to the caller, which was previously ignored.

This one smells more like a theoretical issue than realistic, in that these writes are done only with .hexsz (either 40 or 64) bytes oid string, or a single byte "\n", for either of which it is hard to imagine that it is even remotely close to platform "maximum single I/O size".

But we'd need to look for the error return anyway, so switching to write_in_full() while we are doing so is also good.

Show 31 quoted lines

> Signed-off-by: Randall S. Becker <rsbecker@nexbridge.com>
> ---
>  builtin/repack.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/builtin/repack.c b/builtin/repack.c
> index ede36328a3..932d24c60b 100644
> --- a/builtin/repack.c
> +++ b/builtin/repack.c
> @@ -307,6 +307,7 @@ static int write_oid(const struct object_id *oid,
>  		     struct packed_git *pack UNUSED,
>  		     uint32_t pos UNUSED, void *data)
>  {
> +	int err;
>  	struct child_process *cmd = data;
>  
>  	if (cmd->in == -1) {
> @@ -314,8 +315,12 @@ static int write_oid(const struct object_id *oid,
>  			die(_("could not start pack-objects to repack promisor objects"));
>  	}
>  
> -	xwrite(cmd->in, oid_to_hex(oid), the_hash_algo->hexsz);
> -	xwrite(cmd->in, "\n", 1);
> +	err = write_in_full(cmd->in, oid_to_hex(oid), the_hash_algo->hexsz);
> +	if (err <= 0)
> +		return err;
> +	err = write_in_full(cmd->in, "\n", 1);
> +	if (err <= 0)
> +		return err;
>  	return 0;
>  }