On Thu, Jul 19, 2018 at 05:11:15PM -0400, Eric Sunshine wrote:

On Thu, Jul 19, 2018 at 4:39 PM Jeff King [off-list ref] wrote:

quoted

[...]
Let's start by banning strcpy() and sprintf(). It's not
impossible to use these correctly, but it's easy to do so
incorrectly, and there's always a better option.
[...]
Signed-off-by: Jeff King <redacted>
---

diff --git a/banned.h b/banned.h

@@ -0,0 +1,19 @@
+/*
+ * This header lists functions that have been banned from our code base,
+ * because they're too easy to misuse (and even if used correctly,
+ * complicate audits). Including this header turns them into compile-time
+ * errors.
+ */

When the above talks about "including this header", the implication is
that it must be included _after_ the system header(s) which declare
the banned functions. I wonder if that requirement should be stated
here explicitly.

Hmm, does it need to be? I had originally intended it to be included
before, actually, though in the end I put it later.

I guess it would yield declarations like strcpy_is_banned(), which would
cause _different_ errors (probably link-time ones).

(Probably not worth a re-roll.)

Yeah, I doubt it matters much either way, since the inclusion is done
automatically in git-compat-util.h.

I had also originally imagined this to be triggered via DEVELOPER=1,
with something like "-include banned.h" in CFLAGS. But I think it
probably is appropriate for everybody to run it, since it shouldn't
cause any false positives or other compilation issues.

The one I brainstormed (but forgot to mention) is that it might be
possible for a platform to have strcpy as a macro already? In which case
we'd need to #undef it or risk a compilation error (even if the macro
isn't actually used).

-Peff