Re: [PATCH v6 9/9] sequencer: fallback to sane label in making rebase todo list

> On Mon, Nov 11, 2019 at 01:03:42PM +0700, Doan Tran Cong Danh wrote:
> 
>> In later stage of rebasing, we will make a ref in
>> refs/rewritten/<label>, this label is extracted from the subject of
>> current merge commit.
>>
>> If that subject has forbidden character for refname, git couldn't create
>> the rewritten ref. One such case is the merge commit subject has
>> a multibyte character encoded in ISO-2022-JP.
>>
>> Provide a sane fallback in order to help git-rebase works in such case
> 
> Good find. Not having worked much with this part of the sequencer code,
> I don't have a strong opinion on the fallback label. But it seems better
> than the current behavior would be.

> I suspect there may be other subtle problems, too, for filesystems that
> can't represent some part of the subject (e.g., I wonder if some of your
> ISO-2022-JP tests might already have trouble on HFS+, which excepts all
> paths to be UTF-8).
> 
>> @@ -4607,9 +4608,15 @@ static int make_script_with_merges(struct pretty_print_context *pp,
>>   			if (isspace(*p1))
>>   				*(char *)p1 = '-';
>>   
>> +		hex_oid = oid_to_hex(&commit->object.oid);
>> +
>> +		if (check_refname_format(label.buf, REFNAME_ALLOW_ONELEVEL) < 0) {
>> +			strbuf_reset(&label);
>> +			strbuf_addf(&label, "label-%s", hex_oid);
>> +		}
>> +
>>   		strbuf_reset(&buf);
>> -		strbuf_addf(&buf, "%s -C %s",
>> -			    cmd_merge, oid_to_hex(&commit->object.oid));
>> +		strbuf_addf(&buf, "%s -C %s", cmd_merge, hex_oid);
> 
> A minor nit, but I think it's better here to just call oid_to_hex()
> twice, rather than assigning to the hex_oid variable. It's returning a
> pointer to a static buffer, so holding onto the pointers for too long is
> dangerous. What you have here is definitely OK, because nothing
> interesting happens in between, but seeing any assignment of the result
> of "oid_to_hex" makes auditing harder.
> 
> And it's not like it's that expensive, or that this is
> performance-critical code (and if it were, we'd do better to use
> oid_to_hex_r() directly into the strbuf anyway).
> 
> -Peff
>