[SVN-842] broken copyID inheritance in fs

• Type: Bug
• Status: Closed
• Priority: Blocker
• Resolution: Fixed
• Affects Version/s: all
• Fix Version/s: 0.14.2
• Component/s: libsvn_fs_base

Environment

other

• Assignee: Unassigned
• Reporter: Ben Collins-Sussman
• Created: 01/Aug/02 16:32
• Updated: 27/Oct/18 16:38
• Resolved: 15/Sep/04 08:43

Description

We have a theoretical hole in the way our filesystem causes children
to inherit copyids from parents.  Here's the explanation:

* Say we have a directory D, with a child alpha. alpha has an id of
(1, 0, 5). 1 is the node-id, 0 is the copy-id, 5 is the txn-id.

* svn cp alpha beta and commit.  Now beta is (1, 1, 6), created in rev
6, has a copy id of 1, and the same node-id as alpha.

* svn cp D to D2 and commit.  Now D2 is (?, 2, 7). D2/alpha starts as
(1, 0, 5).  D2/beta starts as (1, 1, 6).

* But if you now edit both children and commit:  they "inherit"
copy-id 2 from D2
and also all get txn-id 8 so they end up with 3 identical components.
 There's no way to tell alpha and beta apart anymore!

Bill Tutt thinks that the copyID inheritnance rule needs to get
smarter:  in the example above, beta should receive copyID 3, as a
"nested branch modification".

Whatever the case:  when this schema bug is fixed, we'll need another
repository dump/load to happen.  :-(

Note that this issue is related to issue #830.