Subject: Re: [PATCH v1 1/3] pkt-line: add packet_write_list_gently()

From: Junio C Hamano <[email-masked]>
Date: Wed, 22 Mar 2017 13:21:20 -0700

Ben Peart <[email-masked]> writes:

> Add packet_write_list_gently() which writes multiple lines in a single
> call and then calls packet_flush_gently(). This is used later in this
> patch series.

I can see how it would be convenient to have a function like this.
I'd name it without _gently(), though.  We call something _gently()
when we initially only have a function that dies hard on error and
later want to have a variant that returns an error for the caller to
handle.  You are starting without a dying variant (which is probably
a preferable way to structure the API).

Also I am hesitant to take a function that does not take any "list"
type argument and yet calls itself "write_list".  IOW, I'd expect
something like these

	write_list(int fd, const char **lines);
	write_list(int fd, struct string_list *lines);

given that name, and not "varargs, each of which is a line".  I am
tempted to suggest

	packet_writel(int fd, const char *line, ...);

noticing similarity with execl(), but perhaps others may be able to
come up with better names.

> Signed-off-by: Ben Peart <[email-masked]>
> ---
>  pkt-line.c | 19 +++++++++++++++++++
>  pkt-line.h |  1 +
>  2 files changed, 20 insertions(+)
>
> diff --git a/pkt-line.c b/pkt-line.c
> index d4b6bfe076..fccdac1352 100644
> --- a/pkt-line.c
> +++ b/pkt-line.c
> @@ -171,6 +171,25 @@ int packet_write_fmt_gently(int fd, const char *fmt, ...)
>  	return status;
>  }
>  
> +int packet_write_list_gently(int fd, const char *line, ...)
> +{
> +	va_list args;
> +	int err;
> +	va_start(args, line);
> +	for (;;) {
> +		if (!line)
> +			break;
> +		if (strlen(line) > LARGE_PACKET_DATA_MAX)
> +			return -1;
> +		err = packet_write_fmt_gently(fd, "%s\n", line);
> +		if (err)
> +			return err;
> +		line = va_arg(args, const char*);
> +	}
> +	va_end(args);
> +	return packet_flush_gently(fd);
> +}
> +
>  static int packet_write_gently(const int fd_out, const char *buf, size_t size)
>  {
>  	static char packet_write_buffer[LARGE_PACKET_MAX];
> diff --git a/pkt-line.h b/pkt-line.h
> index 18eac64830..3674d04509 100644
> --- a/pkt-line.h
> +++ b/pkt-line.h
> @@ -25,6 +25,7 @@ void packet_buf_flush(struct strbuf *buf);
>  void packet_buf_write(struct strbuf *buf, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
>  int packet_flush_gently(int fd);
>  int packet_write_fmt_gently(int fd, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
> +int packet_write_list_gently(int fd, const char *line, ...);
>  int write_packetized_from_fd(int fd_in, int fd_out);
>  int write_packetized_from_buf(const char *src_in, size_t len, int fd_out);