VCS comparison table

[Jelmer Vernooij]

On Mon, 2006-10-23 at 11:45 -0700, Linus Torvalds wrote:
> On Mon, 23 Oct 2006, Jakub Narebski wrote:
> > The place for timestamp and commiter info is in the revision metadata
> > (in commit object in git). Not in revision id. Unless you think that
> > "accidentally the same" doesn't happen...
> Well, git and bzr really do share the same "stable" revision naming, 
> although in git it's more indirect, and thus "covers" more.
> 
> In git, the revision name indirectly includes the commit comments too (and 
> git obviously also distinguishes between "committer" and "author", and 
> those end up being indirectly credited in the name of the commit too). But 
> in a very real sense, the bzr stable ("real") revision name does 
> effectively contain the same things as a git ID: it's just that it's a 
> small subset (only committer+date+random number) of what git includes in 
> its names.
There are no requirements on what a revid is in bzr. It's a unique
identifier, nothing more. It can be whatever you like, as long as it's
unique for that specific commit. The committer+date+random\ number is
just what bzr uses at the moment to create those unique identifiers.

> So you could more easily _fake_ a commit name in bzr, and depending on how 
> things are done it might be more open to malicious attacks for that reason 
> (or unintentionally - if two people apply the exact same patch from an 
> email, and take the author/date info from the email like hit does, you 
> might have clashes. But with a 64-bit random number, that's probably 
> unlikely, unless you also hit some other bad luck like having the 
> pseudo-random sequence seeded by "time()", and people just _happen_ to 
> apply the email at the exact same second).
Bzr stores a checksum of the commit separately from the revision id in
the metadata of a revision. The revision is not used by itself to check
the integrity of a revision.

Cheers,

Jelmer

-- 
Jelmer Vernooij <jelmer at samba.org> - http://samba.org/~jelmer/
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