[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [RFC PATCH 2/6] libxl: stop using libxl__xs_mkdir() for ~/control/shutdown
> -----Original Message----- > From: Ian Jackson [mailto:Ian.Jackson@xxxxxxxxxxxxx] > Sent: 24 November 2015 17:24 > To: Paul Durrant > Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx; Stefano Stabellini; Ian Campbell; Wei Liu > Subject: RE: [RFC PATCH 2/6] libxl: stop using libxl__xs_mkdir() for > ~/control/shutdown > > Paul Durrant writes ("RE: [RFC PATCH 2/6] libxl: stop using libxl__xs_mkdir() > for ~/control/shutdown"): > > [Ian Jackson:] > > > I'm not sure I follow this argument. What did you think of my idea > > > of renaming libxl__xs_mkdir to libxl__xs_mknode ? > > > > The issue, as I said, is the initial state of the node. If you use > > XS_MKDIR then it is not guaranteed to be empty. > > It is guaranteed to be empty if nothing ever wrote anything non-empty > to it. I think participants in xenstore protocols, and users of > xenstore to store things, are entitled to assume that no-one writes > nonempty values to nodes that aren't supposed to have nonempty values. > > And even if the node did somehow end up with a nonempty value, nothing > would break because no-one would read it. Maybe. Personally I would have thought a toolstack would want to put things into a known state and XS_MKDIR just doesn't do that. > > > If you use XS_WRITE then it is and I think that is the correct > > semantic here (even though we happen to get away with it at the > > moment). I'm happy with the function rename, but would you be happy > > with the change in semantic? > > XS_MKDIR creates missing parents, which XS_WRITE doesn't. > According to the documentation it does: (from xenstore.txt) READ <path>| <value|> WRITE <path>|<value|> Store and read the octet string <value> at <path>. WRITE creates any missing parent paths, with empty values. Paul > Ian. _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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