Re: [PATCH] sideband: color lines with keyword only

[Stefan Beller <sbeller@google.com>]

On Mon, Dec 3, 2018 at 3:23 PM Jonathan Nieder <jrnieder@gmail.com> wrote:

> I was curious about what versions of Gerrit this is designed to
> support (or in other words whether it's a bug fix or a feature).
> Looking at examples like [1], it seems that Gerrit historically always
> used "ERROR:" so the 59a255aef0 logic would work for it.  More
> recently, [2] (ReceiveCommits: add a "SUCCESS" marker for successful
> change updates, 2018-08-21) put SUCCESS on a line of its own.  That
> puts this squarely in the new-feature category.

Ooops. From the internal bug, I assumed this to be long standing Gerrit
behavior, which is why I sent it out in -rc to begin with.

> > --- a/sideband.c
> > +++ b/sideband.c
> > @@ -87,7 +87,7 @@ static void maybe_colorize_sideband(struct strbuf *dest, const char *src, int n)
> >               struct keyword_entry *p = keywords + i;
> >               int len = strlen(p->keyword);
> >
> > -             if (n <= len)
> > +             if (n < len)
> >                       continue;
>
> In the old code, we would escape early if 'n == len', but we didn't
> need to.  If 'n == len', then
>
>         src[len] == '\0'

src[len] could also be one of "\n\r", see the caller
recv_sideband for sidebase case 2.

>         src .. &src[len-1] is a valid buffer to read from
>
> so the strncasecmp and strbuf_add operations used in this function are
> valid.  Good.

Yes, they are all valid...

> > -             if (!strncasecmp(p->keyword, src, len) && !isalnum(src[len])) {
> > +             if (!strncasecmp(p->keyword, src, len) &&
> > +                 (len == n || !isalnum(src[len]))) {
>
> Our custom isalnum treats '\0' as not alphanumeric (sane_ctype[0] ==
> GIT_CNTRL) so this part of the patch is unnecessary.  That said, it's
> good for clarity and defensive programming.

... but here we need to check for src[len] for validity.

I made no assumptions about isalnum, but rather needed to shortcut
the condition, as accessing src[len] would be out of bounds, no?

>
> >                       strbuf_addstr(dest, p->color);
> >                       strbuf_add(dest, src, len);

unlike here (or the rest of the block), where len is used correctly.