Re: [PATCH 2/2] blame: simplify prepare_lines()

From: René Scharfe <l.s.r@web.de>
Date: Jun 13, 2014, 21:33 UTC
Message-ID: <539B6E31.1080901@web.de>
In-Reply-To: <20140613211339.GL8557@google.com>

Am 13.06.2014 23:13, schrieb Jonathan Nieder:

Show 12 quoted lines

> René Scharfe wrote:
>
>> -	if (incomplete)
>> -		*lineno++ = len;
>> +	*lineno = len;
>>
>> -	sb->num_lines = num + incomplete;
>> +	sb->num_lines = num;
>
> This will always treat whatever comes after the last newline as an
> incomplete line, even if it has zero length.  Is that safe?  (Not a
> rhetorical question --- I haven't looked carefully at the caller.)

There is no need to look at the caller -- the contents of the lineno array is not (intended to be) changed by the patch.

The original code is:

	p = memchr(p, '\n', end - p);
	if (p) {
		p++;
		*lineno++ = p - buf;
		continue;
	}

Suppose there is no incomplete line. For the last EOL of a buffer, p points to buf[len - 1] after the memchr call. Then it is incremented. Then buf + len - buf is written into the last lineno member -- same as after the patch.

Makes sense?

René