From: Jeff King <peff@peff.net>
Date: Thu, 15 May 2025 20:25:02 GMT
Subject: Re: [PATCH 10/11] bundle-uri: avoid using undefined output of `sscanf()`
Message-ID: <20250515202502.GK3320240@coredump.intra.peff.net>
In-Reply-To: <4dc3e2335afb42e5006ead7b9b18d33bdae7238f.1747314709.git.gitgitgadget@gmail.com>

On Thu, May 15, 2025 at 01:11:48PM +0000, Johannes Schindelin via GitGitGadget wrote:

> In c429bed102 (bundle-uri: store fetch.bundleCreationToken, 2023-01-31)
> code was introduced that assumes that an `sscanf()` call leaves its
> output variables unchanged unless the return value indicates success.
> 
> However, the POSIX documentation makes no such guarantee:
> https://pubs.opengroup.org/onlinepubs/9699919799/functions/sscanf.html
> 
> So let's make sure that the output variable `maxCreationToken` is
> always well-defined.

Definitely an issue, but...why are we using sscanf() at all?

Wouldn't strtoul() be the usual thing in our code base? Or even just
repo_config_get_ulong()? The behavior of the latter would differ in that
we'd complain about a garbage value in fetch.bundlecreationtoken, but
wouldn't that be a good thing?

-Peff