Re: [PATCH 16/21] compat/fsmonitor: remove dependency on `the_repository` in Darwin IPC

From: brian m. carlson <sandals@crustytoothpaste.net>
Date: Jun 11, 2024, 23:16 UTC
Message-ID: <Zmjas3s9OPJ9Ff5E@tapette.crustytoothpaste.net>
In-Reply-To: <d4e87f9d6b4813fe359e22f4b5d5ebda28e09a08.1718106285.git.ps@pks.im>

On 2024-06-11 at 11:58:47, Patrick Steinhardt wrote:

Show 15 quoted lines

> The IPC socket used by the fsmonitor on Darwin is usually contained in
> the Git repository itself. When the repository is hosted on a networked
> filesystem though, we instead create the socket path in the user's home
> directory or the socket directory. In that case, we derive the path by
> hashing the repository path.
> 
> The hashing implicitly depends on `the_repository` though via
> `hash_to_hex()`. For one, this is wrong because we really should be
> using the passed-in repository. But arguably, it is not sensible to
> derive the path hash from the repository's object hash in the first
> place -- they don't have anything to do with each other, and a
> repository that is hosted in the same path should always derive the same
> IPC socket path.
> 
> Fix this by unconditionally using SHA1 to derive the path.

Let's instead use SHA-256 to derive the path. I can imagine that there might be a time when some users would like to drop support for SHA-1 altogether (for FIPS compliance reasons, say) and we'll make our lives a lot easier if we avoid more uses of SHA-1.

It is also typically faster when compiled appropriately, although the amount of data we're processing is very small.

-- 
brian m. carlson (they/them or he/him)
Toronto, Ontario, CA