[darcs-devel] [issue2318] hashed_inventory is vulnerable to unguided search and replace

[Ben Franksen]

Ben Franksen <ben.franksen at online.de> added the comment:

> I think 'head' is a good idea. Is your intention to keep writing out both
> head and hashed_inventory to maintain backwards compatibility?

I see no other option if we want to maintain compatibility with existing
darcs versions.

> If so one option would be to read both and let hashed_inventory
> override head if they differ.
If we do that then a corrupt hashed_inventory will take precedence, too,
so we wouldn't gain anything regarding the issue at hand.

> It feels messy though and I would worry a bit about atomicity.

The messiness can be handled with suitable engineering (i.e. encapsulation).

I haven't given any thought to atomicity yet, but I don't expect this to
be a serious problem. (I may be wrong about that.)

I think the correct way to handle compatibility is by adding a new
format property as an alternative to "hashed"; let me use "head" as a
stawman. It means a repo with

  hashed|head

can be read but not modified by darcs versions that don't know "head".

A better name for the format property might be "branched" or just "branch".

__________________________________
Darcs bug tracker <bugs at darcs.net>
<http://bugs.darcs.net/issue2318>
__________________________________