# acl.py - changeset access control for mercurial
#
# Copyright 2006 Vadim Gelfer <vadim.gelfer@gmail.com>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

'''hooks for controlling repository access

This hook makes it possible to allow or deny write access to given branches and
paths of a repository when receiving incoming changesets via pretxnchangegroup
and pretxncommit.

The authorization is matched based on the local user name on the
system where the hook runs, and not the committer of the original
changeset (since the latter is merely informative).

The acl hook is best used along with a restricted shell like hgsh,
preventing authenticating users from doing anything other than
pushing or pulling. The hook is not safe to use if users have
interactive shell access, as they can then disable the hook.
Nor is it safe if remote users share an account, because then there
is no way to distinguish them.

The order in which access checks are performed is:
1) Deny  list for branches (section [acl.deny.branches])
2) Allow list for branches (section [acl.allow.branches])
3) Deny  list for paths    (section [acl.deny])
4) Allow list for paths    (section [acl.allow])

The allow and deny sections take key-value pairs.

--- Branch-based Access Control ---

Use the [acl.deny.branches] and [acl.allow.branches] sections to have
branch-based access control.

Keys in these sections can be either:
1) a branch name
2) an asterisk, to match any branch;

The corresponding values can be either:
1) a comma-separated list containing users and groups.
2) an asterisk, to match anyone;

--- Path-based Access Control ---

Use the [acl.deny] and [acl.allow] sections to have path-based access control.
Keys in these sections accept a subtree pattern (with a glob syntax by default).
The corresponding values follow the same syntax as the other sections above.

--- Groups ---

Group names must be prefixed with an @ symbol.
Specifying a group name has the same effect as specifying all the users in
that group.
The set of users for a group is taken from "grp.getgrnam"
(see http://docs.python.org/library/grp.html#grp.getgrnam).

--- Example Configuration ---

  [hooks]

  # Use this if you want to check access restrictions at commit time
  pretxncommit.acl = python:hgext.acl.hook
  
  # Use this if you want to check access restrictions for pull, push, bundle
  # and serve.
  pretxnchangegroup.acl = python:hgext.acl.hook

  [acl]
  # Check whether the source of incoming changes is in this list
  # ("serve" == ssh or http, "push", "pull", "bundle")
  sources = serve

  [acl.deny.branches] 
  
  # Everyone is denied to the frozen branch: 
  frozen-branch = * 
  
  # A bad user is denied on all branches: 
  * = bad-user 
  
  [acl.allow.branches] 
  
  # A few users are allowed on branch-a: 
  branch-a = user-1, user-2, user-3 
  
  # Only one user is allowed on branch-b: 
  branch-b = user-1 
  
  # The super user is allowed on any branch: 
  * = super-user 
  
  # Everyone is allowed on branch-for-tests: 
  branch-for-tests = * 

  [acl.deny]
  # If a match is found, "acl.allow" will not be checked.
  # if acl.deny is not present, no users denied by default
  # empty acl.deny = all users allowed
  # Format for both lists: glob pattern = user4, user5, @group1

  # To match everyone, use an asterisk for the user:
  # my/glob/pattern = *

  # user6 will not have write access to any file:
  ** = user6

  # Group "hg-denied" will not have write access to any file:
  ** = @hg-denied

  # Nobody will be able to change "DONT-TOUCH-THIS.txt", despite everyone being
  # able to change all other files. See below.
  src/main/resources/DONT-TOUCH-THIS.txt = *

  [acl.allow]
  # if acl.allow not present, all users allowed by default
  # empty acl.allow = no users allowed

  # User "doc_writer" has write access to any file under the "docs" folder:
  docs/** = doc_writer

  # User "jack" and group "designers" have write access to any file under the
  # "images" folder:
  images/** = jack, @designers

  # Everyone (except for "user6" - see "acl.deny" above) will have write access
  to any file under the "resources" folder (except for 1 file. See "acl.deny"):
  src/main/resources/** = *

  .hgtags = release_engineer

'''

from mercurial.i18n import _
from mercurial import util, match
import getpass, urllib, grp

def _getusers(group):
    return grp.getgrnam(group).gr_mem

def _usermatch(user, usersorgroups):

    if usersorgroups == '*':
        return True

    for ug in usersorgroups.replace(',', ' ').split():
        if user == ug or ug.find('@') == 0 and user in _getusers(ug[1:]):
            return True

    return False

def buildmatch(ui, repo, user, key):
    '''return tuple of (match function, list enabled).'''
    if not ui.has_section(key):
        ui.debug('acl: %s not enabled\n' % key)
        return None

    pats = [pat for pat, users in ui.configitems(key)
            if _usermatch(user, users)]
    ui.debug('acl: %s enabled, %d entries for user %s\n' %
             (key, len(pats), user))

    if not repo:
        if pats:
            return lambda b: '*' in pats or b in pats
        return lambda b: False

    if pats:
        return match.match(repo.root, '', pats)
    return match.exact(repo.root, '', [])


def hook(ui, repo, hooktype, node=None, source=None, **kwargs):
    if hooktype not in ['pretxnchangegroup', 'pretxncommit']:
        raise util.Abort(_('config error - hook type "%s" cannot stop '
                           'incoming changesets nor commits') % hooktype)
    if (hooktype == 'pretxnchangegroup' and
        source not in ui.config('acl', 'sources', 'serve').split()):
        ui.debug('acl: changes have source "%s" - skipping\n' % source)
        return

    user = None
    if source == 'serve' and 'url' in kwargs:
        url = kwargs['url'].split(':')
        if url[0] == 'remote' and url[1].startswith('http'):
            user = urllib.unquote(url[3])

    if user is None:
        user = getpass.getuser()

    cfg = ui.config('acl', 'config')
    if cfg:
        ui.readconfig(cfg, sections = ['acl.allow.branches',
        'acl.deny.branches', 'acl.allow', 'acl.deny'])

    allowbranches = buildmatch(ui, None, user, 'acl.allow.branches')
    denybranches = buildmatch(ui, None, user, 'acl.deny.branches')
    allow = buildmatch(ui, repo, user, 'acl.allow')
    deny = buildmatch(ui, repo, user, 'acl.deny')

    for rev in xrange(repo[node], len(repo)):
        ctx = repo[rev]
        branch = ctx.branch()
        if denybranches and denybranches(branch):
            raise util.Abort(_('acl: user "%s" denied on branch "%s"'
                               ' (changeset "%s")')
                               % (user, branch, ctx))
        if allowbranches and not allowbranches(branch):
            raise util.Abort(_('acl: user "%s" not allowed on branch "%s"'
                               ' (changeset "%s")')
                               % (user, branch, ctx))
        ui.debug('acl: branch access granted: "%s" on branch "%s"\n'
        % (ctx, branch))

        for f in ctx.files():
            if deny and deny(f):
                ui.debug('acl: user %s denied on %s\n' % (user, f))
                raise util.Abort(_('acl: access denied for changeset %s') % ctx)
            if allow and not allow(f):
                ui.debug('acl: user %s not allowed on %s\n' % (user, f))
                raise util.Abort(_('acl: access denied for changeset %s') % ctx)
        ui.debug('acl: allowing changeset %s\n' % ctx)