RFE: download patch between arbitrary revisions

[john at keeping.me.uk (John Keeping)]

On Sun, Jun 16, 2013 at 09:56:55AM +0200, Lukas Fleischer wrote:
> On Thu, Jun 13, 2013 at 11:21:26PM +0100, John Keeping wrote:
> > On Thu, Jun 13, 2013 at 11:58:10PM +0200, Lukas Fleischer wrote:
> > > On Mon, Jun 03, 2013 at 07:49:53PM +0100, John Keeping wrote:
> > > > On Sun, Jun 02, 2013 at 09:19:11PM -0400, Konstantin Ryabitsev wrote:
> > > > > There is currently a way to render a diff between two arbitrary objects,
> > > > > e.g.:
> > > > > 
> > > > > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/diff/?id=v3.10-rc4&id2=v3.10-rc3
> > > > > 
> > > > > However, there doesn't appear to be a way to download a patch in the
> > > > > same way -- it will only make patch against id's parent. E.g.:
> > > > > 
> > > > > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/patch/?id=v3.10-rc4&id2=v3.10-rc3
> > > > > 
> > > > > Any way we can make the behaviour of patch match that of diff?
> > > > 
> > [...]
> > 
> > So:
> > 
> >     /patch/?id=v1.8.3.1&id2=v1.8.3
> > 
> > generates something like "git format-patch v1.8.3..v1.8.3.1".  And
> > 
> >     /rawdiff/?id=v1.8.3.1&id2=v1.8.3
> > 
> > generates the diff with no HTML around it.
> > 
> > The latter could be a query parameter instead ("raw=1"?).  Having not
> > investigated the impact on the code, I have no preference for one over
> > the other.
> 
> Sounds good to me either way. Jason?
> 
> Also, I just wondered whether this could be used to DoS servers when
> requesting a series of patches for a huge range of revisions... Maybe
> there should be some kind of limit?

The "diff" version costs about the same regardless of how many revisions
are between the endpoints - it's purely a function of the size of the
tree (and the number of changed files which probably is affected by how
far apart the commits are, but it's still bounded by the size of the
tree).

I can see it potentially being a problem in the "format-patch" case, so
perhaps we want to add a "max-patches-per-request" variable if we do
implement that.