On Mon, Jun 29, 2020 at 10:08 PM Junio C Hamano <gitster@xxxxxxxxx> wrote: > > "Han-Wen Nienhuys via GitGitGadget" <gitgitgadget@xxxxxxxxx> writes: > > > From: Han-Wen Nienhuys <hanwen@xxxxxxxxxx> > > > > Reftable precisely reproduces the given message. This leads to differences, > > because the files backend implicitly adds a trailing '\n' to all messages. > > What does this mean? With the files backend we'll now see a > redundant two LFs in a row? I think you are careful enough not to > introduce unnecessary compatibility breakage like that, so perhaps > "implicitly adds" is a wrong way to characterize what happens in the > files backend, and it only adds LF when the message does not end > with one, but does not add an extra one if not necessary? > > If so, then the change in the patch does not break compatibility, > but the above description does not give readers confidence that it > is indeed the case. IOW it is unclear how this change manages to > avoid breaking existing code. > > Sorry, but I am left puzzled. Most places that write a reflog message use a message that ends with '\n'. Some places (the one mentioned here) do not append a '\n'. When it is read back, the message does have a '\n', leading to discrepancies with reftable (which faithfully reproduced the message without '\n') I initially thought we could or should fix this across git-core, but I think it will be a lot of work to find all occurrences, so I implemented https://github.com/google/reftable/commit/785f745daf567aeabe47cb01024ea879b9e15c2f which does extra validation on reflog messages, and normalizes the '\n' at the end. Maybe this is also worth discussing in the reftable spec: in reftable, you can use multi-line reflog messages, but that seems fundamentally impossible in the traditional file storage. I can drop this commit from the series, but I think it would be a useful cleanup anyways. -- Han-Wen Nienhuys - Google Munich I work 80%. Don't expect answers from me on Fridays. -- Google Germany GmbH, Erika-Mann-Strasse 33, 80636 Munich Registergericht und -nummer: Hamburg, HRB 86891 Sitz der Gesellschaft: Hamburg Geschäftsführer: Paul Manicle, Halimah DeLaine Prado -- Google Germany GmbH, Erika-Mann-Strasse 33, 80636 Munich Registergericht und -nummer: Hamburg, HRB 86891 Sitz der Gesellschaft: Hamburg Geschäftsführer: Paul Manicle, Halimah DeLaine Prado
