Re: [PATCH 6/9] http: update base URLs when we see redirects

> On Sun, Sep 29, 2013 at 03:26:45PM -0400, Eric Sunshine wrote:
>
>> On Sat, Sep 28, 2013 at 4:34 AM, Jeff King <peff@peff.net> wrote:
>> > diff --git a/http.c b/http.c
>> > index 65a0048..8775b5c 100644
>> > --- a/http.c
>> > +++ b/http.c
>> > @@ -921,11 +921,71 @@ static int http_request_reauth(const char *url,
>> > +static int update_url_from_redirect(struct strbuf *base,
>> > +                                   const char *asked,
>> > +                                   const struct strbuf *got)
>> > +{
>> > +       const char *tail;
>> > +       size_t tail_len;
>> > +
>> > +       if (!strcmp(asked, got->buf))
>> > +               return 0;
>> > +
>> > +       if (strncmp(asked, base->buf, base->len))
>> > +               die("BUG: update_url_from_redirect: %s is not a superset of %s",
>> > +                   asked, base->buf);
>>
>> Is there something non-obvious going on here? die(...,base->buf) takes
>> advantage of the terminating NUL promised by strbuf, but then
>> strncmp(...,base->buf,base->len) is used rather than the simpler
>> strcmp(...,base->buf).
>
> Yes, we are not checking for equality, but rather making sure that
> "asked" begins with "base->buf". It might be more clearly written as:

>
>   if (prefixcmp(asked, base->buf))
>
> I was trying to take advantage of the fact that we know base->len
> already, but this it not a particularly performance-critical code path.
> We can afford the extra strlen that prefixcmp will do.
>
> -Peff