Re: [PATCH v3] http.c: use CURLOPT_RANGE for range requests

[David Turner <dturner@twopensource.com>]

On Mon, 2015-11-02 at 17:10 -0500, Jeff King wrote:
> On Mon, Nov 02, 2015 at 10:50:10PM +0100, Andreas Schwab wrote:
> 
> > Jeff King <peff@peff.net> writes:
> > 
> > >   4. Fix all of the callers. I suspect this would involve calling
> > >      fstat(fileno(fh)) to get a real off_t.
> > 
> > You can also use ftello which returns off_t.
> 
> Thanks, I forgot about that function. That would probably be the sanest
> path forward.
> 
> I think it is as simple as this (on top of David's patch):
> 
> -- >8 --
> Subject: [PATCH] http: use off_t to store partial file size
> 
> When we try to resume transfer of a partially-downloaded
> object or pack, we fopen() the existing file for append,
> then use ftell() to get the current position. We use a
> "long", which can hold only 2GB on a 32-bit system, even
> though packfiles may be larger than that.
> 
> Let's switch to using off_t, which should hold any file size
> our system is capable of storing. We need to use ftello() to
> get the off_t. This is in POSIX and hopefully available
> everywhere; if not, we should be able to wrap it by falling
> back to ftell(), which would presumably return "-1" on such
> a large file (and we would simply skip resuming in that case).

It would skip resuming, but would still maybe write to the end of the
existing file, right?  So I think we would need to seek to the beginning
of the file in that case.

(other than that, lgtm)