Re: [PATCH 1/2] mailinfo: extract is_from_line from mailsplit

From: Junio C Hamano <gitster@pobox.com>
Date: Jul 25, 2016, 18:03 UTC
Message-ID: <xmqqmvl561ez.fsf@gitster.mtv.corp.google.com>
In-Reply-To: <m2poq3zdu3.fsf@linux-m68k.org>

Andreas Schwab <schwab@linux-m68k.org> writes:

Show 26 quoted lines

>> +	colon = line + len - 2;
>> +	line += 5;
>> +	for (;;) {
>> +		if (colon < line)
>> +			return 0;
>> +		if (*--colon == ':')
>> +			break;
>> +	}
>> +
>> +	if (!isdigit(colon[-4]) ||
>> +	    !isdigit(colon[-2]) ||
>> +	    !isdigit(colon[-1]) ||
>> +	    !isdigit(colon[ 1]) ||
>> +	    !isdigit(colon[ 2]))
>> +		return 0;
>> +
>> +	/* year */
>> +	if (strtol(colon+3, NULL, 10) <= 90)
>> +		return 0;
>> +
>> +	/* Ok, close enough */
>> +	return 1;
>> +}
>
> Should this be made more strict, like by checking for a space before the
> year?

The function seems to judge the line to be "close enough" by checking these places (please view with fixed-width font ;-):

    From me Mon Jul 25 01:23:45 2016
    xxxxx               x xxxxx ....

We only see if the year part is more than 90 but we do not even ensure that it is at the end of the line without any further garbage, which I think is probably OK for the purpose of "close enough".

We also do not bother rejecting a single-digit hour, or there is a colon between the hour and minute part.

I would say requiring SP between the year and the second, and requiring colon between hour and minute, would probably be a good change, i.e. something like this:

	if (!isdigit(colon[-4]) ||
	    colon[-3] != ':' ||
	    !isdigit(colon[-2]) ||
	    !isdigit(colon[-1]) ||
	    !isdigit(colon[ 1]) ||
	    !isdigit(colon[ 2]) ||
	    colon[3] != ' ')

would be safe enough without increasing the false negatives too much.