Re: [PATCH 4/8] strbuf: add strbuf_read_once to read without blocking

> The new call will read from a file descriptor into a strbuf once. The
> underlying call xread_nonblock is meant to execute without blocking if
> the file descriptor is set to O_NONBLOCK. It is a bug to call
> strbuf_read_once on a file descriptor which would block.
>
> Signed-off-by: Stefan Beller <sbeller@google.com>
> Signed-off-by: Junio C Hamano <gitster@pobox.com>
> ---
> diff --git a/strbuf.h b/strbuf.h
> @@ -367,6 +367,14 @@ extern size_t strbuf_fread(struct strbuf *, size_t, FILE *);
>  extern ssize_t strbuf_read(struct strbuf *, int fd, size_t hint);
>
>  /**
> + * Returns the number of new bytes appended to the sb.
> + * Negative return value signals there was an error returned from
> + * underlying read(2), in which case the caller should check errno.
> + * e.g. errno == EAGAIN when the read may have blocked.
> + */
> +extern ssize_t strbuf_read_once(struct strbuf *, int fd, size_t hint);