contrib/hg-ssh

discovery: add new set-based discovery

Adds a new discovery method based on repeatedly sampling the still
undecided subset of the local node graph to determine the set of nodes
common to both the client and the server.

For small differences between client and server, it uses about the same
or slightly fewer roundtrips than the old tree-based discovery. For
larger differences, it typically reduces the number of roundtrips
drastically (from 150 to 4, for instance).

The old discovery code now lives in treediscovery.py, the new code is
in setdiscovery.py.

Still missing is a hook for extensions to contribute nodes to the
initial sample. For instance, Augie's remotebranches could contribute
the last known state of the server's heads.

Credits for the actual sampler and computing common heads instead of
bases go to Benoit Boissinot.

#!/usr/bin/env python
#
# Copyright 2005-2007 by Intevation GmbH <[e-mail]>
#
# Author(s):
# Thomas Arendsen Hein <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

"""
hg-ssh - a wrapper for ssh access to a limited set of mercurial repos

To be used in ~/.ssh/authorized_keys with the "command" option, see sshd(8):
command="hg-ssh path/to/repo1 /path/to/repo2 ~/repo3 ~user/repo4" ssh-dss ...
(probably together with these other useful options:
 no-port-forwarding,no-X11-forwarding,no-agent-forwarding)

This allows pull/push over ssh from/to the repositories given as arguments.

If all your repositories are subdirectories of a common directory, you can
allow shorter paths with:
command="cd path/to/my/repositories && hg-ssh repo1 subdir/repo2"

You can use pattern matching of your normal shell, e.g.:
command="cd repos && hg-ssh user/thomas/* projects/{mercurial,foo}"
"""

# enable importing on demand to reduce startup time
from mercurial import demandimport; demandimport.enable()

from mercurial import dispatch

import sys, os

cwd = os.getcwd()
allowed_paths = [os.path.normpath(os.path.join(cwd, os.path.expanduser(path)))
                 for path in sys.argv[1:]]
orig_cmd = os.getenv('SSH_ORIGINAL_COMMAND', '?')

if orig_cmd.startswith('hg -R ') and orig_cmd.endswith(' serve --stdio'):
    path = orig_cmd[6:-14]
    repo = os.path.normpath(os.path.join(cwd, os.path.expanduser(path)))
    if repo in allowed_paths:
        dispatch.dispatch(['-R', repo, 'serve', '--stdio'])
    else:
        sys.stderr.write("Illegal repository %r\n" % repo)
        sys.exit(-1)
else:
    sys.stderr.write("Illegal command %r\n" % orig_cmd)
    sys.exit(-1)