subiquity/subiquitycore/utils.py

# Copyright 2015 Canonical, Ltd.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as
# published by the Free Software Foundation, either version 3 of the
# License, or (at your option) any later version.
#
# This program 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 Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

import crypt
import errno
import logging
import os
import random
import sys
import yaml
from subprocess import Popen, PIPE, call
from subiquitycore.async import Async

log = logging.getLogger("subiquitycore.utils")
SYS_CLASS_NET = "/sys/class/net/"
ENVIRONMENT_CHECK = '''
checks:
    read:
        file:
            - /var/log/syslog
    write:
        directory:
            - /tmp
    mount:
        directory:
            - /proc
            - /sys
    exec:
        file:
            - /sbin/hdparm
            - /usr/bin/curtin
'''


def environment_check(check=ENVIRONMENT_CHECK):
    ''' Check the environment to ensure subiquity can run without issues.
    '''
    log.info('Checking environment for installer requirements...')

    def is_file(x):
        return os.path.isfile(x)

    def is_directory(x):
        return os.path.isdir(x)

    def is_mount(x):
        return os.path.ismount(x)

    def is_writable(x):
        return os.access(x, os.W_OK)

    def is_readable(x):
        return os.access(x, os.R_OK)

    def is_executable(x):
        return os.access(x, os.X_OK)

    check_map = {
        'read': is_readable,
        'write': is_writable,
        'exec': is_executable,
        'file': is_file,
        'directory': is_directory,
        'mount': is_mount,
    }

    checks = yaml.safe_load(check).get('checks', None)
    if not checks:
        log.error('Invalid environment check configuration')
        return False

    env_ok = True
    for check_type in [c for c in checks
                       if c in ['read', 'write', 'mount', 'exec']]:
        for ftype, items in checks[check_type].items():
            for i in items:
                if not os.path.exists(i):
                    log.error('FAIL: {} is not found on the'
                              ' filesystem'.format(i))
                    env_ok = False
                    continue
                if check_map[ftype](i) is False:
                    log.error('FAIL: {} is NOT of type: {}'.format(i, ftype))
                    env_ok = False
                    continue
                if check_map[check_type](i) is False:
                    log.error('FAIL: {} does NOT have required attr:'
                              ' {}'.format(i, check_type))
                    env_ok = False

    return env_ok


def run_command_async(cmd, timeout=None):
    log.debug('calling Async command: {}'.format(cmd))
    return Async.pool.submit(run_command, cmd, timeout)


def run_command(command, timeout=None, shell=False):
    """ Execute command through system shell
    :param command: command to run
    :param timeout: (optional) use 'timeout' to limit time. default 300
    :type command: str
    :returns: {status: returncode, output: stdout, err: stderr}
    :rtype: dict
    .. code::
        # Get output of juju status
        cmd_dict = utils.get_command_output('juju status')
    """
    log.debug('run_command called: {}'.format(command))
    cmd_env = os.environ.copy()
    # set consistent locale
    cmd_env['LC_ALL'] = 'C'
    if timeout:
        command = "timeout %ds %s" % (timeout, command)

    try:
        log.debug('trying Popen...')
        # dummy stdin fd as per:
        # http://stackoverflow.com/ +
        # questions/27022810/urwid-watch-file-blocks-keypress
        r, w = os.pipe()
        p = Popen(command, shell=shell,
                  stdin=r, stdout=PIPE, stderr=PIPE,
                  bufsize=-1, env=cmd_env, close_fds=True)
        os.close(w)
    except OSError as e:
        if e.errno == errno.ENOENT:
            log.debug('error!')
            return dict(ret=127, output="", err="")
        else:
            log.debug('error raise!')
            raise e
    log.debug('calling communicate()')
    stdout, stderr = p.communicate()
    if p.returncode == 126 or p.returncode == 127:
        stdout = bytes()
    if not stderr:
        stderr = bytes()
    rv = dict(status=p.returncode,
              output=stdout.decode('utf-8'),
              err=stderr.decode('utf-8'))
    log.debug('run_command returning: {}'.format(rv))
    return rv


def sys_dev_path(devname, path=""):
    return SYS_CLASS_NET + devname + "/" + path


def read_sys_net(devname, path, translate=None, enoent=None, keyerror=None):
    try:
        contents = ""
        with open(sys_dev_path(devname, path), "r") as fp:
            contents = fp.read().strip()
        if translate is None:
            return contents

        try:
            return translate.get(contents)
        except KeyError:
            log.debug("found unexpected value '%s' in '%s/%s'", contents,
                      devname, path)
            if keyerror is not None:
                return keyerror
            raise
    except OSError as e:
        if e.errno == errno.ENOENT and enoent is not None:
            return enoent
        raise


# FIXME: replace with passlib and update package deps
def crypt_password(passwd, algo='SHA-512'):
    # encryption algo - id pairs for crypt()
    algos = {'SHA-512': '$6$', 'SHA-256': '$5$', 'MD5': '$1$', 'DES': ''}
    if algo not in algos:
        raise Exception('Invalid algo({}), must be one of: {}. '.format(
            algo, ','.join(algos.keys())))

    salt_set = ('abcdefghijklmnopqrstuvwxyz'
                'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
                '0123456789./')
    salt = 16 * ' '
    salt = ''.join([random.choice(salt_set) for c in salt])
    return crypt.crypt(passwd, algos[algo] + salt)


def is_root():
    """ Returns root or if sudo user exists
    """
    euid = os.geteuid()

    log.debug('is_root: euid={}'.format(euid))
    if euid != 0:
        return False
    return True


def sudo_user():
    """ Returns the value of env['SUDO_USER']
    """
    sudo_user = os.getenv('SUDO_USER', None)
    return sudo_user


def mark_firstboot_complete():
    """ Touch our firstboot-complete eyecatcher """
    log.info('marking firstboot service complete')
    firstboot = '/var/lib/firstboot/firstboot-complete'
    if not os.path.exists(os.path.dirname(firstboot)):
        os.makedirs(os.path.dirname(firstboot))
    with open(firstboot, 'w') as fp:
        os.utime(fp.name, None)
        fp.close()


def disable_first_boot_service():
    """ Stop firstboot service; which also restores getty service """
    log.info('disabling first boot service')
    tty = os.ttyname(sys.stdout.fileno()).split("/")[-1]
    if not tty.startswith('tty'):
        log.debug('tty is not tty: %s , skipping service shutdown', tty)
        return

    cmd = "systemctl stop firstboot@%s" % tty
    log.info("disabling firstboot service with %s", cmd)
    fid = os.fork()
    if fid == 0:
        try:
            call([cmd])
            os._exit(0)
        except:
            log.warn("%s returned non-zero" % cmd)
            os._exit(1)
    return