#============================================================================
# This library is free software; you can redistribute it and/or
# modify it under the terms of version 2.1 of the GNU Lesser General Public
# License as published by the Free Software Foundation.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
#============================================================================
# Copyright (C) 2006 International Business Machines Corp.
# Author: Reiner Sailer <sailer@us.ibm.com>
# Author: Bryan D. Payne <bdpayne@us.ibm.com>
#============================================================================

"""Labeling a domain configuration file or a resource.
"""
import os
import sys

from xen.util import dictio
from xen.util import security
from xen.xm.opts import OptionError

def help():
    return """
    Format: xm addlabel <label> dom <configfile> [<policy>]
            xm addlabel <label> res <resource> [<policy>]
    
    This program adds an acm_label entry into the 'configfile'
    for a domain or to the global resource label file for a
    resource. It derives the policy from the running hypervisor
    if it is not given (optional parameter). If a label already
    exists for the given domain or resource, then addlabel fails."""


def validate_config_file(configfile):
    """Performs a simple sanity check on the configuration file passed on
       the command line.  We basically just want to make sure that it's
       not a domain image file so we check for a few configuration values
       and then we are satisfied.  Returned 1 on success, otherwise 0.
    """
    # read in the config file
    globs = {}
    locs = {}
    try:
        execfile(configfile, globs, locs)
    except:
        print "Invalid configuration file."
        return 0

    # sanity check on the data from the file
    count = 0
    required = ['kernel', 'memory', 'name']
    for (k, v) in locs.items():
        if k in required:
            count += 1
    if count != 3:
        print "Invalid configuration file."
        return 0
    else:
        return 1


def add_resource_label(label, resource, policyref):
    """Adds a resource label to the global resource label file.
    """
    # sanity check: make sure this label can be instantiated later on
    ssidref = security.label2ssidref(label, policyref, 'res')

    #build canonical resource name
    resource = security.unify_resname(resource)

    # see if this resource is already in the file
    access_control = {}
    file = security.res_label_filename
    try:
        access_control = dictio.dict_read("resources", file)
    except:
        print "Resource file not found, creating new file at:"
        print "%s" % (file)

    if access_control.has_key(resource):
        security.err("This resource is already labeled.")

    # write the data to file
    new_entry = { resource : tuple([policyref, label]) }
    access_control.update(new_entry)
    dictio.dict_write(access_control, "resources", file)


def add_domain_label(label, configfile, policyref):
    # sanity checks: make sure this label can be instantiated later on
    ssidref = security.label2ssidref(label, policyref, 'dom')

    new_label = "access_control = ['policy=%s,label=%s']\n" % (policyref, label)
    if not os.path.isfile(configfile):
        security.err("Configuration file \'" + configfile + "\' not found.")
    config_fd = open(configfile, "ra+")
    for line in config_fd:
        if not security.access_control_re.match(line):
            continue
        config_fd.close()
        security.err("Config file \'" + configfile + "\' is already labeled.")
    config_fd.write(new_label)
    config_fd.close()


def main(argv):
    policyref = None
    if len(argv) not in (4, 5):
        raise OptionError('Needs either 2 or 3 arguments')
    
    label = argv[1]
    
    if len(argv) == 5:
        policyref = argv[4]
    elif security.on():
        policyref = security.active_policy
    else:
        raise OptionError("No active policy. Must specify policy on the "
                          "command line.")

    if argv[2].lower() == "dom":
        configfile = argv[3]
        if configfile[0] != '/':
            for prefix in [".", "/etc/xen"]:
                configfile = prefix + "/" + configfile
                if os.path.isfile(configfile):
                    break
        if not validate_config_file(configfile):
            raise OptionError('Invalid config file')
        else:
            add_domain_label(label, configfile, policyref)
    elif argv[2].lower() == "res":
        resource = argv[3]
        add_resource_label(label, resource, policyref)
    else:
        raise OptionError('Need to specify either "dom" or "res" as '
                          'object to add label to.')
            
if __name__ == '__main__':
    try:
        main(sys.argv)
    except Exception, e:
        sys.stderr.write('Error: %s\n' % str(e))
        sys.exit(-1)