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- Committer: Canonical.com Patch Queue Manager
- Date: 2008-01-04 02:49:07 UTC
- mfrom: (3112.1.5 contrib_bzr_access)
- Revision ID: pqm@pqm.ubuntu.com-20080104024907-k4ld11wri0m0tvxq
(Balint Aradi) Add contrib/bzr_access to allow some access control
via a single user based on ssh-keys.
via a single user based on ssh-keys.
- files added:
- contrib/bzr_access
added
removed
contrib/bzr_access
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#!/usr/bin/env python
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###############################################################################
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#
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# bzr_access:
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# Simple access control for shared bazaar repository accessed over ssh.
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#
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# Copyright (C) 2007 Balint Aradi
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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#
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###############################################################################
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"""
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Invocation: bzr_access <bzr_executable> <repo_collection> <user>
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The script extracts from the SSH_ORIGINAL_COMMAND environment variable the
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repository, which bazaar tries to access through the bzr+ssh protocol. The
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repository is assumed to be relative to <repo_collection>. Based
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on the configuration file <repo_collection>/bzr_access.conf it determines
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the access rights (denied, read-only, read-write) for the specified user.
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If the user has read-only or read-write access a bazaar smart server is
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started for it in read-only or in read-write mode, rsp., using the specified
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bzr executable.
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Config file: INI format, pretty much similar to the authfile of subversion.
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Groups can be defined in the [groups] section. The options in this block are
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the names of the groups to be defined, the corresponding values the lists of
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the users belonging to the given groups. (User names must be separated by
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commas.)
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All other sections names should be path names (starting with '/'), defining
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the permissions for the given path. The options in those sections are user
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names or group references (group name with a leading '@'), the corresponding
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values are the permissions: 'rw', 'r' and '' (without the quotes) for
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read-write, read-only and no access, respectively.
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Only the options in the section with the longest matching name are evaluated.
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The last relevant option for the user is used.
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Sample bzr_access.conf::
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[groups]
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admins = alpha
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devels = beta, gamma, delta
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[/test/trunk]
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@admins = rw
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@devels = r
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[/test/branches]
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@admins = rw
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@devels = rw
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This allows you to set up a single SSH user, and customize the access based on
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ssh key. Your ``.ssh/authorized_key`` file should look something like this::
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command="/path/to/bzr_access /path/to/bzr /path/to/repository <username>",no-port-forwarding,no-X11-forwarding,no-agent-forwarding ssh-<type> <key>
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"""
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import ConfigParser
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import os
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import re
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import subprocess
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import sys
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CONFIG_FILE = "bzr_access.conf"
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SCRIPT_NAME = os.path.basename(sys.argv[0])
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# Permission constants
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PERM_DENIED = 0
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PERM_READ = 1
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PERM_READWRITE = 2
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PERM_DICT = { "r": PERM_READ, "rw": PERM_READWRITE }
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# Exit codes
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EXIT_BAD_NR_ARG = 1
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EXIT_BZR_NOEXEC = 2
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EXIT_REPO_NOREAD = 3
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EXIT_BADENV = 4
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EXIT_BADDIR = 5
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EXIT_NOCONF = 6
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EXIT_NOACCESS = 7
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EXIT_BADUSERNAME = 8
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# pattern for the bzr command passed to ssh
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PAT_SSH_COMMAND = re.compile(r"""^bzr\s+
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serve\s+
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--inet\s+
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--directory=(?P<dir>\S+)\s+
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--allow-writes\s*$""", re.VERBOSE)
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# Command line for starting bzr
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BZR_OPTIONS = ['serve', '--inet', '--directory']
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BZR_READWRITE_FLAGS = ['--allow-writes']
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def error(msg, exit_code):
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"""Prints error message to stdout and exits with given error code."""
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print >>sys.stderr, "%s::error: %s" % (SCRIPT_NAME, msg)
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sys.exit(exit_code)
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class AccessManager(object):
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"""Manages the permissions, can be queried for a specific user and path."""
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def __init__(self, fp):
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""":param fp: File like object, containing the configuration options.
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"""
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# TODO: jam 20071211 Consider switching to bzrlib.util.configobj
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self.config = ConfigParser.ConfigParser()
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self.config.readfp(fp)
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self.groups = {}
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if self.config.has_section("groups"):
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for group, users in self.config.items("groups"):
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self.groups[group] = set([ s.strip() for s in users.split(",")])
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def permission(self, user, path):
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"""Determines the permission for a given user and a given path
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:param user: user to look for.
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:param path: path to look for.
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:return: permission.
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"""
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if not path.startswith("/"):
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return PERM_DENIED
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perm = PERM_DENIED
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pathFound = False
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while not pathFound and path != "/":
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print >>sys.stderr, "DEBUG:", path
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pathFound = self.config.has_section(path)
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if (pathFound):
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options = reversed(self.config.options(path))
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for option in options:
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value = PERM_DICT.get(self.config.get(path, option),
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PERM_DENIED)
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if self._is_relevant(option, user):
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perm = value
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else:
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path = os.path.dirname(path)
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return perm
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def _is_relevant(self, option, user):
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"""Decides if a certain option is relevant for a given user.
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An option is relevant if it is identical with the user or with a
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reference to a group including the user.
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:param option: Option to check.
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:param user: User
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:return: True if option is relevant for the user, False otherwise.
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"""
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if option.startswith("@"):
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result = (user in self.groups.get(option[1:], set()))
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else:
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result = (option == user)
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return result
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def get_directory(command):
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"""Extracts the directory name from the command pass to ssh.
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:param command: command to parse.
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:return: Directory name or empty string, if directory was not found or if it
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does not start with '/'.
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"""
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match = PAT_SSH_COMMAND.match(command)
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if not match:
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return ""
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directory = match.group("dir")
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return os.path.normpath(directory)
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############################################################################
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# Main program
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############################################################################
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def main():
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# Read arguments
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if len(sys.argv) != 4:
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error("Invalid number or arguments.", EXIT_BAD_NR_ARG)
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(bzrExec, repoRoot, user) = sys.argv[1:4]
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# Sanity checks
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if not os.access(bzrExec, os.X_OK):
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error("bzr is not executable.", EXIT_BZR_NOEXEC)
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if not os.access(repoRoot, os.R_OK):
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error("Path to repository not readable.", EXIT_REPO_NOREAD)
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# Extract the repository path from the command passed to ssh.
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if not os.environ.has_key("SSH_ORIGINAL_COMMAND"):
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error("Environment variable SSH_ORIGINAL_COMMAND missing.", EXIT_BADENV)
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directory = get_directory(os.environ["SSH_ORIGINAL_COMMAND"])
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if len(directory) == 0:
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error("Bad directory name.", EXIT_BADDIR)
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# Control user name
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if not user.isalnum():
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error("Invalid user name", EXIT_BADUSERNAME)
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# Read in config file.
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try:
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fp = open(os.path.join(repoRoot, CONFIG_FILE), "r")
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try:
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accessMan = AccessManager(fp)
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finally:
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fp.close()
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except IOError:
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error("Can't read config file.", EXIT_NOCONF)
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# Determine permission and execute bzr with appropriate options
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perm = accessMan.permission(user, directory)
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absDir = os.path.join(repoRoot, directory)
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command = [bzrExec] + BZR_OPTIONS + [absDir]
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if perm == PERM_READ:
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# Nothing extra needed for readonly operations
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pass
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elif perm == PERM_READWRITE:
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# Add the write flags
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command.extend(BZR_READWRITE_FLAGS)
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else:
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error("Access denied.", EXIT_NOACCESS)
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return subprocess.call(command)
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if __name__ == "__main__":
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main()
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### Local Variables:
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### mode:python
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### End:
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