Re: [PATCH 07/17] commit: increase commit message buffer size

[Ben Peart <peartben@gmail.com>]

On 7/9/2018 7:39 PM, brian m. carlson wrote:
> On Mon, Jul 09, 2018 at 10:45:33AM -0700, Junio C Hamano wrote:
>> Derrick Stolee <stolee@gmail.com> writes:
>>
>>> On 7/8/2018 7:36 PM, brian m. carlson wrote:
>>>> diff --git a/refs/files-backend.c b/refs/files-backend.c
>>>> index a9a066dcfb..252f835bae 100644
>>>> --- a/refs/files-backend.c
>>>> +++ b/refs/files-backend.c
>>>> @@ -1587,7 +1587,7 @@ static int log_ref_write_fd(int fd, const struct object_id *old_oid,
>>>>    	char *logrec;
>>>>      	msglen = msg ? strlen(msg) : 0;
>>>> -	maxlen = strlen(committer) + msglen + 100;
>>>> +	maxlen = strlen(committer) + msglen + 200;
>>>>    	logrec = xmalloc(maxlen);
>>>>    	len = xsnprintf(logrec, maxlen, "%s %s %s\n",
>>>>    			oid_to_hex(old_oid),
>>>
>>> nit: 100 is not enough anymore, but wasn't a very descriptive
>>> value. 200 may be enough now, but I'm not sure why.
> 
> 200 is definitely enough.  Suppose we had a message consisting entirely
> of SHA-1 hashes (5, at 20 bytes a piece).  If our new hash is 32 bytes
> long, then it would require at most 160 bytes.
> 
> I only noticed this because the old code segfaulted.  My approach to
> using a 32-byte hash was to set it up, do some basic tests, find out
> what crashed, and fix it.  Most of this series is the basics necessary
> to get the most rudimentary functionality out of a 32-byte Git,
> excluding the index pieces, which are necessarily inelegant.
> 
> I didn't include them because there are other ways to implement the
> changes which are more elegant in some ways and less elegant in other
> ways, and I want to think more about it before I send them in.
> 
>> As Brandon alludes to downthread, we probably should use strbuf for
>> things like this these days, so a preliminary clean-up to do so is
>> probably a welcome change to sneak in and rebase this series on top
>> of.
> 
> Sure, I agree that would be a better change, and I'm happy to reroll
> with that.
> 

I've put together a patch to update log_ref_write_fd() to use strbuf and 
will submit it shortly.