Re: [PATCH 1/2] introduce "banned function" list

From: Theodore Y. Ts'o <tytso@mit.edu>
Date: Jul 20, 2018, 13:22 UTC
Message-ID: <20180720132241.GN30706@thunk.org>
In-Reply-To: <20180720010808.GC2179@sigill.intra.peff.net>

On Thu, Jul 19, 2018 at 09:08:08PM -0400, Jeff King wrote:

> Ditto for sprintf, where you should _always_ be using at least xsnprintf
> (or some better tool, depending on the situation).  And for strncpy,
> strlcpy (or again, some better tool) is strictly an improvement.

Nitpick: this may be true for git, but it's not strictly true in all
cases.  I actually have a (non-git) case where strncpy *is* the right
tool.  And this is one where I'm copying a NUL-terminated string into
a fixed-length charater array (in the ext4 superblock) which is *not*
NUL-terminated.  In that case, strncpy works(); but strlcpy() does not
do what I want.

So I used strncpy() advisedly, and I ignore people running Coccinelle scripts and blindly sending patches to "fix" ext4.

But perhaps that's also a solution for git? You don't have to necessarily put them on a banned list; you could instead have some handy, pre-set scripts that scan the entire code base looking for "bad" functions with cleanups automatically suggested. This could be run at patch review time, and/or periodically (especially before a release).

						- Ted