Re: [PATCH] pack-format: correct multi-pack-index description

[Junio C Hamano <gitster@pobox.com>]

Derrick Stolee <stolee@gmail.com> writes:

> On 2/7/2020 5:16 PM, Johannes Berg wrote:
>> The description of the multi-pack-index contains a small bug,
>> if all offsets are < 2^32 then there will be no LOFF chunk,
>> not only if they're all < 2^31 (since the highest bit is only
>> needed as the "LOFF-escape" when that's actually needed.)
>> 
>> Correct this, and clarify that in that case only offsets up
>> to 2^31-1 can be stored in the OOFF chunk.
>> 
>> Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
>> ---
>>  Documentation/technical/pack-format.txt | 5 +++--
>>  1 file changed, 3 insertions(+), 2 deletions(-)
>> 
>> diff --git a/Documentation/technical/pack-format.txt b/Documentation/technical/pack-format.txt
>> index cab5bdd2ff0f..d3a142c65202 100644
>> --- a/Documentation/technical/pack-format.txt
>> +++ b/Documentation/technical/pack-format.txt
>> @@ -315,10 +315,11 @@ CHUNK DATA:
>>  	    Stores two 4-byte values for every object.
>>  	    1: The pack-int-id for the pack storing this object.
>>  	    2: The offset within the pack.
>> -		If all offsets are less than 2^31, then the large offset chunk
>> +		If all offsets are less than 2^32, then the large offset chunk
>>  		will not exist and offsets are stored as in IDX v1.
>>  		If there is at least one offset value larger than 2^32-1, then
>> -		the large offset chunk must exist. If the large offset chunk
>> +		the large offset chunk must exist, and offsets larger than
>> +		2^31-1 must be stored in it instead. If the large offset chunk
>>  		exists and the 31st bit is on, then removing that bit reveals
>>  		the row in the large offsets containing the 8-byte offset of
>>  		this object.
>
> Thank you for finding this doc bug. This is a very subtle point,
> and you have described it very clearly.

Thanks, both; queued.