On 20/05/2025 18:59, Taylor Blau wrote:
On Tue, May 20, 2025 at 04:04:25PM +0100, Phillip Wood wrote:From: Phillip Wood <phillip.wood@xxxxxxxxxxxxx> On a 64 bit system the calculation p->pack_size * pack_info[i].referenced_objects could overflow. If a pack file contains 2^28 objects with an average compressed size of 1KB then the pack size will be 2^38B. If all of the objects are referenced by the multi-pack index the sum above will overflow. Avoid this by using shifted integer arithmetic and changing the order of the calculation so that the pack size is divided by the total number of objects in the pack before multiplying by the number of objects referenced by the multi-pack index. Using a shift of 14 bits should give reasonable accuracy while avoiding overflow for pack sizes less that 1PB.Ahhh, this renders some of comments on the previous patch moot. I think that this is a not-unreasonable concern to be addressing even on modern 64-bit systems, since I have definitely encountered packs that have on the order of ~2^28 objects in them.
Thanks, that's good to know Phillip
I like this approach quite a bit, thanks! Thanks, Taylor
