Index of /project/darcs-fast-export

1. Purpose and Features

darcs-fast-export is a tool to dump a darcs repository in a format understood by "fast-importers" such as git fast-import. It exhibits the following features:

Fast

darcs-fast-export provides a fast darcs backend for fast-import. See here for exact details.

Correct

darcs-fast-export produces correct results in any extreme cases. It has been tested with a collection of large darcs repos (called big-zoo). And several testcases under the t/ directory.

Independent

Ideally it should work with any fast importer, but actually it has been tested with git fast-import, bzr fast-import and hg fastimport. (These are the three fast-import implementations available ATM.)
hg fastimport needs three patches. While they are not in the upstream, you can get it from my repository using

$ hg clone static-http://frugalware.org/~vmiklos/hg/hg-fastimport

Formats

It supports the darcs-2, hashed, and old-fashioned-inventory darcs repository formats.

Incremental conversions

It supports the usual --export-marks / --import-marks switches to allow incremental conversion.

Wrapper scripts

A wrapper script called d2x is available if you find typing --export-marks / --import-marks all the time boring. A similar one is also provided for the other direction, called x2d. Finally, if you want to work on darcs repos with git, you can use the git-darcs wrapper.

Author mappings

Supports --authors-file option like Git’s SVN adaptor, for DARCS repositories that originated in CVS or SVN.

Import script

The pair of darcs-fast-export, darcs-fast-import is also included in this repo. It has been tested with the fast-expoters of Git, Hg, Bzr and - of course - Darcs itself.

Two-way sync

Using darcs-fast-export / darcs-fast-import, it is possible to convert a darcs repo to an other VCS, work there, then convert your work back to Darcs (or vica versa). This has been tested with "darcs → git; hack hack; git → darcs".

2. Usage

See the manpages:

2.1. Example

Assuming that test/ is a darcs repo, you could do this:

$ mkdir test.git
$ cd test.git
$ git --bare init
$ cd ..
$ darcs-fast-export test |(cd test.git; git fast-import)

For more examples (especially for bzr and hg), see the t/ directory.

4. Status

In general, darcs-fast-export should work fine. darcs-fast-import has known problems with tags - other than that it should be okay. git-darcs should work properly as long as you are not paying too much attention to the imported tags (newly created tags won’t be pushed back).

darcs-fast-export has been tested with the following versions:

Darcs version (see this bug on why do you need such a new version):

$ darcs --version
2.2.0 (release)

Git version:

$ git --version
git version 1.6.0.2

Bzr versions:

$ bzr version
Bazaar (bzr) 1.12
$ (cd ~/bzr/fastimport; bzr log --limit 1|grep revno)
revno: 181

Yes, you need the fastiport plugin from BZR, the last hg release series supported by fastimport-0.6 is hg-1.0.x.

Mercurial (Hg) version:

$ hg version
Mercurial Distributed SCM (version 1.2.1)

Strictly speaking this document is a wrong place to talk about enabling hg plugins. However…

$ cat ~/.hgrc
[extensions]
hgext.fastimport=

and once you installed the plugin correctly, you should have something like:

$ ls /usr/lib/python*/site-packages/hgext/fastimport/__init__.py
/usr/lib/python2.5/site-packages/hgext/fastimport/__init__.py

6. Alternatives

darcs2git tries to find conflict resolutions (to map them to merge commits), but it’s rather slow because of this. It does not support the darcs2 format and/or incremental conversions, either. darcs-fast-export may support mapping to merge commits later, but not before this issue is addressed.
tailor is an any2any VCS converter, but it produces corrupted results when converting the big-zoo - see this ticket.
darcs-to-git is similar to darcs2git, but it fails for the testcases found in the testsuite of darcs-fast-export.
undarcs claims to be fast, but its own README says it produces incorrect results. When I tried, it did not handle the darcs2 format, binary files and incremental support.

7. Thanks

Jason Dagit for helping me with darcs2 issues
Shawn O. Pearce and Johannes Schindelin for writing git-fast-import / git-fast-export
Ian Clatworthy for writing bzr fast-import
Paul Crowley for writing hg fast-import
Matthias Andree for assorted improvements, among them the --help, --encoding and --authors-file features (using Python’s optparse), support for hashed repositories, _darcs/format interpretation, and mangling whitespace in tags to cope with repos imported into DARCS from CVS.
Pieter de Bie for writing git-bzr, which was the base of git-darcs