Re: Possible oversight in setvbuf()

[Rich Felker <dalias@libc.org>]

On Fri, Jul 13, 2018 at 05:46:54PM -0400, Christopher Friedt wrote:
> On Fri, Jul 13, 2018, 5:31 PM Rich Felker, <dalias@libc.org> wrote:
> 
> > One thing this highlights is that we could really use better testing
> > and security review process. I'll write and
> >
> 
> Using some static analysis tool would be good too - not sure if that's in
> use already.

We have in the past, and they caught a small number of real issues
along with a lot of false positives. Stuff like this is hard for
static analysis to test without also having knowledge of the relevant
interface contract(s).

> A good process for adding new features is to add tests with them. Even if
> there is only a test for expected behaviour, at least it will catch one
> possible regression.

Yes, I should really do that more. Sometimes it's not obvious what
should be tested though. In the case of setvbuf, the intended behavior
is in some sense untestable (the previous implementation not using the
caller-provided buffer was valid); in hindsight the obvious important
thing to test is that it doesn't result in writes outside the buffer.

Rich