On Tue, Dec 2, 2014 at 3:28 PM, Bryan Turner <bturner@xxxxxxxxxxxxx> wrote: > On Tue, Dec 2, 2014 at 2:34 PM, Jonathan Nieder <jrnieder@xxxxxxxxx> wrote: >> Hi Bryan, >> >> Bryan Turner wrote: >> >>> Is there actually logic somewhere in Git that does that "MAY walk >>> backwards" step? >> >> Yes. See upload-pack.c::check_non_tip and >> http://thread.gmane.org/gmane.comp.version-control.git/178814. > > Jonathan, > > Thanks for the reply! I realize now I didn't really cite the part of > that documentation that I'm most interested in, which is: "through > history _or through the reflog_". It's the reflog bit I'm looking for. > Sorry for not being more clear. check_non_tip appears to look at > ancestry, walking back up (or down, depending on your view) the DAG to > see if the requested SHA-1 is reachable from a current ref, so it > looks like that's covering the "through history" part of that blurb. > > The reason I ask is that there is a race condition that exists where > the ref advertisement lists refs/heads/foo at abc1234, and then foo is > deleted before the actual upload-pack request comes in. In that > situation, walking backwards through _history_ will only allow the > upload-pack to complete unless the deleted ref was merged into another s/unless/if, sorry. "In that situation, walking backwards through history will only allow the upload-pack to complete if the deleted ref was merged into another ref." > ref prior to being deleted (if I understand the code correctly). It > seems like looking at the reflogs, and seeing that refs/heads/foo did > in fact exist and did in fact refer to abc1234, is the only approach > that could allow the upload-pack to complete. The documentation hints > that such a thing is possible, but I don't see any code in Git that > seems to do that. > > Does that make more sense? Does that functionality exist and I've just > overlooked it? > > Thanks again, > Bryan Turner > >> >> Hope that helps, >> Jonathan -- To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html