From: Derrick Stolee <stolee@gmail.com>
Date: Wed, 29 Apr 2026 13:28:45 GMT
Subject: Re: [PATCH 4/6] delta, packfile: use size_t for delta header sizes
Message-ID: <1b2ce8fe-7c99-4dde-ae07-1443d03cf523@gmail.com>
In-Reply-To: <3274cba862ae42a6813710410274a692ec0f5d29.1777393580.git.gitgitgadget@gmail.com>

On 4/28/26 12:26 PM, Johannes Schindelin via GitGitGadget wrote:
> From: Johannes Schindelin <johannes.schindelin@gmx.de>
> 
> The delta header decoding functions return unsigned long, which
> truncates on Windows for objects larger than 4GB. Introduce size_t
> variants get_delta_hdr_size_sz() and get_size_from_delta_sz() that
> preserve the full 64-bit size, and use them in packed_object_info()
> where the size is needed for streaming decisions.

> + * Size_t variant that doesn't truncate - use for >4GB objects on Windows.
> + */
> +static inline size_t get_delta_hdr_size_sz(const unsigned char **datap,
> +					   const unsigned char *top)
...
> +static inline unsigned long get_delta_hdr_size(const unsigned char **datap,
> +					       const unsigned char *top)
> +{
> +	size_t size = get_delta_hdr_size_sz(datap, top);
>   	return cast_size_t_to_ulong(size);
>   }

I like this trick to use the 64-bit implementation and only to
down-cast for API compatibility. This allows a more gradual
transition than if we replaced ulongs with size_ts everywhere
at once.

Thanks,
-Stolee