Re: [PATCH v4 02/35] pkt-line: allow peeking a packet line without consuming it

From: Junio C Hamano <gitster@pobox.com>
Date: Mar 1, 2018, 20:48 UTC
Message-ID: <xmqqk1uvfro3.fsf@gitster-ct.c.googlers.com>
In-Reply-To: <20180228232252.102167-3-bmwill@google.com>

Brandon Williams <bmwill@google.com> writes:

Show 31 quoted lines

> +enum packet_read_status packet_reader_read(struct packet_reader *reader)
> +{
> +	if (reader->line_peeked) {
> +		reader->line_peeked = 0;
> +		return reader->status;
> +	}
> +
> +	reader->status = packet_read_with_status(reader->fd,
> +						 &reader->src_buffer,
> +						 &reader->src_len,
> +						 reader->buffer,
> +						 reader->buffer_size,
> +						 &reader->pktlen,
> +						 reader->options);
> +
> +	switch (reader->status) {
> +	case PACKET_READ_EOF:
> +		reader->pktlen = -1;
> +		reader->line = NULL;
> +		break;
> +	case PACKET_READ_NORMAL:
> +		reader->line = reader->buffer;
> +		break;
> +	case PACKET_READ_FLUSH:
> +		reader->pktlen = 0;
> +		reader->line = NULL;
> +		break;
> +	}
> +
> +	return reader->status;
> +}

With the way _peek() interface interacts with the reader instance (which by the way I find is well designed), it is understandable that we want almost everything available in reader's fields, but having to manually clear pktlen field upon non NORMAL status feels a bit strange.

Perhaps that is because the underlying packet_read_with_status() does not set *pktlen in these cases? Shouldn't it be doing that so the caller does not have to?

A similar comment applies for reader's line field. In priniciple, as the status field is part of a reader, it does not have to exist as a separate field, i.e.

	#define line_of(reader) \
		((reader).status == PACKET_READ_NORMAL ? \
		(reader).buffer : NULL)

can be used to as substitute for it. I guess it depends on how the actual callers wants to use this interface.