On Fri, Jan 04, 2019 at 11:26:56AM -0800, Junio C Hamano wrote:
> "brian m. carlson" <sandals@crustytoothpaste.net> writes:
> 
> >>  - --dereference to control whether to follow symlinks
> >
> > This is actually surprisingly difficult. The reason I implemented this
> > only for no-index mode is because there are actually several places we
> > can stat a file in the diff code, and implementing a --dereference
> > option that catches all of those cases and getting the option passed
> > down to them is non-trivial.
> 
> Another thing to worry about is symlinks that point outside the
> working tree.  When a tracked content "dir/link" is a symlink to
> "/etc/motd", it probably makes sense to open("/etc/motd") and read()
> it on the working tree side of the diff, and probably even on the
> index side of the diff, but what about obtaining contents for
> "dir/link" in a year-old commit under --deference mode?  I am not
> sure if it makes sense to read from the filesystem in such a case.
> 
> I personally am perfectly fine if this "do not compare readlink(2),
> but read contents literally" is limited to the --no-index mode.

That's a good point. I think I'll stick with the current design, then,
since that seems like the least surprising way forward. It also means
that we don't read outside of the working tree unless --no-index is in
use, which may be beneficial for security purposes.

Thanks for a helpful perspective.
-- 
brian m. carlson: Houston, Texas, US
OpenPGP: https://keybase.io/bk2204