From: Ben Peart <peartben@gmail.com>
Date: Tue, 25 Apr 2017 15:09:11 GMT
Subject: Re: [PATCH v6 1/8] pkt-line: add packet_read_line_gently()
Message-ID: <4cadf613-7923-e8bb-c889-34e1bf5eb47c@gmail.com>
In-Reply-To: <xmqqbmrlxm8m.fsf@gitster.mtv.corp.google.com>

Sorry if you get this twice, somehow Thunderbird converted my response 
to HTML


On 4/24/2017 10:19 PM, Junio C Hamano wrote:
> Ben Peart <peartben@gmail.com> writes:
>
>> On 4/24/2017 12:21 AM, Junio C Hamano wrote:
>>> Ben Peart <peartben@gmail.com> writes:
>>>
>>> +{ 
>>>> +	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.
>> packet_read() returns -1 when PACKET_READ_GENTLE_ON_EOF is passed and
>> it hits truncated output from the remote process.
> I know, but that is irrelevant to my question, which is about
> CHOMP_NEWLINE.  I didn't even ask "why a negative len treated
> specially?"  My question is about the case where len == 0.  Your
> patch treats len==0 just like len==-1, i.e. an error, but I do not
> know if that is correct, hence my question.  We both know len < 0
> is an error and you do not need to waste time elaborating on it.
>
>

The packet_read_line() function returns NULL when len == 0 and 
PACKET_READ_CHOMP_NEWLINE is passed so I wrote the similar 
packet_read_line_gently() function to behave the same.

How about I update the comment in the function header to make this more 
clear:

diff --git a/pkt-line.h b/pkt-line.h
index 7c278a158b..b2965869ad 100644
--- a/pkt-line.h
+++ b/pkt-line.h
@@ -78,9 +78,10 @@ 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.
+ * is not NULL it will return NULL for a flush packet or when the number of
+ * bytes copied is zero 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);