#!/usr/bin/env python

"""

hg-ssh - limit access to hg repositories reached via ssh.  Part of

mercurial-server.

It is called by ssh due to an entry in the authorized_keys file,

with the name for the key passed on the command line.

It uses SSH_ORIGINAL_COMMAND to determine what the user was trying to

do and to what repository, and then checks each rule in the rule file

in turn for a matching rule which decides what to do, defaulting to

disallowing the action.

"""

# enable importing on demand to reduce startup time

from mercurial import demandimport; demandimport.enable()

from mercurial import dispatch

import sys, os, os.path

import base64

from mercurialserver import config, ruleset

def fail(message):

    sys.stderr.write("mercurial-server: %s\n" % message)

    sys.exit(-1)

def checkDots(path):

    head, tail = os.path.split(path)

    if tail.startswith("."):

        fail("paths cannot contain dot file components")

    if head:

        checkDots(head)

def checkParents(path):

    path = os.path.dirname(path)

    if path == "":

        return

    if os.path.exists(path + "/.hg"):

        fail("Cannot create repo under existing repo")

    checkParents(path)

def getrepo(op, repo):

    # First canonicalise, then check the string, then the rules

    # and finally the filesystem.

    repo = repo.rstrip("/")

    if len(repo) == 0:

        fail("path to repository seems to be empty")

    if repo.startswith("/"):

        fail("absolute paths are not supported")

    checkDots(repo)

    ruleset.rules.set(repo=repo)

    if not ruleset.rules.allow(op, branch=None, file=None):

        fail("access denied")

    checkParents(repo)

    return repo

config.initExe()

if len(sys.argv) == 3 and sys.argv[1] == "--base64":

    ruleset.rules.set(user = base64.b64decode(sys.argv[2]))

elif len(sys.argv) == 2:

    ruleset.rules.set(user = sys.argv[1])

else:

    fail("hg-ssh wrongly called, is authorized_keys corrupt? (%s)" 

        % sys.argv)

for k,v in config.getEnv():

    os.environ[k.upper()] = v

os.chdir(config.getReposPath())

for f in config.getAccessPaths():

    if os.path.isfile(f):

        ruleset.rules.readfile(f)

cmd = os.environ.get('SSH_ORIGINAL_COMMAND', None)

if cmd is None:

    fail("direct logins on the hg account prohibited")

elif cmd.startswith('hg -R ') and cmd.endswith(' serve --stdio'):

    repo = getrepo("read", cmd[6:-14])

    if not os.path.isdir(repo + "/.hg"):

        fail("no such repository %s" % repo)

    dispatch.dispatch(['-R', repo, 'serve', '--stdio'])

elif cmd.startswith('hg init '):

    repo = getrepo("init", cmd[8:])

    if os.path.exists(repo):

        fail("%s exists" % repo)

    d = os.path.dirname(repo)

    if d != "" and not os.path.isdir(d):

        os.makedirs(d)

    dispatch.dispatch(['init', repo])

else:

    fail("illegal command %r" % cmd)