Daniel Shahaf <d...@daniel.shahaf.name> writes: > Philip Martin wrote on Tue, 15 Jun 2010 at 11:16 -0000: > >> Then the repos layer can loop (in practice only if the >> use_pre_revprop_change_hook flag is set): >> >> do >> svn_fs_revision_prop(¤t_value) >> action = ... >> svn_repos__hooks_pre_revprop_change(action) >> error = svn_fs_change_rev_prop2(current_value, new_value) >> while error is current value doesn't match >> >> This doesn't alter the fact that the revprop can change at any time >> during the loop but that doesn't matter. The revprop is unversioned >> so only the current state matters and the above will guarantee that >> the current state when the change is made is equal to the state >> validated by the pre-revprop-change hook. >> > > If we just upgrade the svn_fs_change_rev_prop() call in > svn_repos_fs_change_rev_prop3() to svn_fs_change_rev_prop2() (a > single-line change),
Slightly more than one line if we make libsvn_repos absorb the BAD_PROPERTY and loop. If we don't loop then if neither of use_pre_revprop_change_hook and use_post_revprop_change_hook is set then perhaps we should not pass the old value. That preserves the existing behaviour and the checking is pointless if there are no hook scripts > then we will be guaranteed that the 'action' > parameter (A/D/M) will be accurate. (However, the pre- hook script doesn't > know the old property value.) And getting the old value into the script is tricky. It's binary so it cannot be passed as a parameter directly. It either needs to be encoded, or passed via a file descriptor (and not stdin since that is used for the new value). > This is sufficient for the svnsync use case (issue 3546), where "allow > adds/deletes only" will provide the necessary mutual exclusion. > > But I wonder if, while here, we could go further and obtain the > "expected old property value" from the RA layer (and pass it to the pre- > hook). (This probably means revving svn_ra_change_rev_prop() the same > way svn_fs_change_rev_prop() was revved.) That will allow "svn propset > k v --if-old-value-is=vprime" to work... Perhaps. It would require both client and server upgrades and I don't think there is any way we can provide backward compatibility, so a new client would have to detect old servers and report some not-supported error. -- Philip
