Re: [PATCH 02/10] builtin/index-pack.c: convert trivial snprintf calls to xsnprintf

From: Ramsay Jones <ramsay@ramsayjones.plus.com>
Date: Jun 3, 2016, 15:32 UTC
Message-ID: <5751A319.1030806@ramsayjones.plus.com>
In-Reply-To: <20160603085320.GC28401@sigill.intra.peff.net>

On 03/06/16 09:53, Jeff King wrote:

Show 19 quoted lines

> On Fri, Jun 03, 2016 at 07:47:16AM +0000, Elia Pinto wrote:
> 
>> diff --git a/builtin/index-pack.c b/builtin/index-pack.c
>> index e8c71fc..c032fe7 100644
>> --- a/builtin/index-pack.c
>> +++ b/builtin/index-pack.c
>> @@ -1443,7 +1443,7 @@ static void final(const char *final_pack_name, const char *curr_pack_name,
>>  		printf("%s\n", sha1_to_hex(sha1));
>>  	} else {
>>  		char buf[48];
>> -		int len = snprintf(buf, sizeof(buf), "%s\t%s\n",
>> +		int len = xsnprintf(buf, sizeof(buf), "%s\t%s\n",
>>  				   report, sha1_to_hex(sha1));
>>  		write_or_die(1, buf, len);
> 
> So it's pretty unclear here whether that 48 is big enough (it is, if you
> read the whole function, because "report" is always a 4-char string).
> Yuck. At least there should be a comment explaining why 48 is big
> enough.

Agreed, again I would use something like:

		char buf[GIT_SHA1_HEXSZ + 7]; /* 40 (sha1) + 4 (report) + 3 (\t\n\0) */

(and yes yuck - is report ever likely to increase? "bitmap" perhaps?)

ATB, Ramsay Jones