Re: [PATCH v6 1/8] pkt-line: add packet_read_line_gently()

[Junio C Hamano <gitster@pobox.com>]

Ben Peart <peartben@gmail.com> writes:

> Add packet_read_line_gently() to enable reading a line without dying on
> EOF.
>
> Signed-off-by: Ben Peart <benpeart@microsoft.com>
> ---
>  pkt-line.c | 14 +++++++++++++-
>  pkt-line.h | 10 ++++++++++
>  2 files changed, 23 insertions(+), 1 deletion(-)
>
> diff --git a/pkt-line.c b/pkt-line.c
> index d4b6bfe076..bfdb177b34 100644
> --- a/pkt-line.c
> +++ b/pkt-line.c
> @@ -315,7 +315,7 @@ static char *packet_read_line_generic(int fd,
>  			      PACKET_READ_CHOMP_NEWLINE);
>  	if (dst_len)
>  		*dst_len = len;
> -	return len ? packet_buffer : NULL;
> +	return (len > 0) ? packet_buffer : NULL;
>  }

The log does not seem to explain what this change is about.  

Is this supposed to be a preliminary bugfix where this helper used
to return a non-NULL buffer when underlying packet_read() signaled
an error by returning a negative len?  If so, this should probably
be a separate patch early in the series.

Should len==0 be considered an error?  Especially given that
PACKET_READ_CHOMP_NEWLINE is in use, I would expect that len==0
should be treated similarly to positive length, i.e. the otherside
gave us an empty line.

>  char *packet_read_line(int fd, int *len_p)
> @@ -323,6 +323,18 @@ char *packet_read_line(int fd, int *len_p)
>  	return packet_read_line_generic(fd, NULL, NULL, len_p);
>  }
>  
> +int packet_read_line_gently(int fd, int *dst_len, char** dst_line)

ERROR: "foo** bar" should be "foo **bar"
#29: FILE: pkt-line.c:326:
+int packet_read_line_gently(int fd, int *dst_len, char** dst_line)

> +{
> +	int len = packet_read(fd, NULL, NULL,
> +			      packet_buffer, sizeof(packet_buffer),
> +			      PACKET_READ_CHOMP_NEWLINE|PACKET_READ_GENTLE_ON_EOF);
> +	if (dst_len)
> +		*dst_len = len;
> +	if (dst_line)
> +		*dst_line = (len > 0) ? packet_buffer : NULL;

I have the same doubt as above for len == 0 case.

> +	return len;
> +}
> +
>  char *packet_read_line_buf(char **src, size_t *src_len, int *dst_len)
>  {
>  	return packet_read_line_generic(-1, src, src_len, dst_len);
> diff --git a/pkt-line.h b/pkt-line.h
> index 18eac64830..ad30db101a 100644
> --- a/pkt-line.h
> +++ b/pkt-line.h
> @@ -74,6 +74,16 @@ int packet_read(int fd, char **src_buffer, size_t *src_len, char
>  char *packet_read_line(int fd, int *size);
>  
>  /*
> + * Convenience wrapper for packet_read that sets the PACKET_READ_GENTLE_ON_EOF
> + * and CHOMP_NEWLINE options. The return value specifies the number of bytes
> + * read into the buffer or -1 on truncated input. If the *dst_line parameter
> + * is not NULL it will return NULL for a flush packet and otherwise points to
> + * a static buffer (that may be overwritten by subsequent calls). If the size
> + * parameter is not NULL, the length of the packet is written to it.
> + */
> +int packet_read_line_gently(int fd, int *size, char** dst_line);
> +
> +/*
>   * Same as packet_read_line, but read from a buf rather than a descriptor;
>   * see packet_read for details on how src_* is used.
>   */