Mini Shell

"""
This compat module handles various platform specific calls that do not fall into one
particular category.
"""
from __future__ import absolute_import

import logging
import select
import subprocess
import sys

from certbot import errors
from certbot.compat import os

from acme.magic_typing import Tuple, Optional

try:
    from win32com.shell import shell as shellwin32
    POSIX_MODE = False
except ImportError:  # pragma: no cover
    POSIX_MODE = True


logger = logging.getLogger(__name__)

# For Linux: define OS specific standard binary directories
STANDARD_BINARY_DIRS = ["/usr/sbin", "/usr/local/bin", "/usr/local/sbin"] if POSIX_MODE else []


def raise_for_non_administrative_windows_rights():
    # type: () -> None
    """
    On Windows, raise if current shell does not have the administrative rights.
    Do nothing on Linux.

    :raises .errors.Error: If the current shell does not have administrative rights on Windows.
    """
    if not POSIX_MODE and shellwin32.IsUserAnAdmin() == 0:  # pragma: no cover
        raise errors.Error('Error, certbot must be run on a shell with administrative rights.')


def readline_with_timeout(timeout, prompt):
    # type: (float, str) -> str
    """
    Read user input to return the first line entered, or raise after specified timeout.

    :param float timeout: The timeout in seconds given to the user.
    :param str prompt: The prompt message to display to the user.

    :returns: The first line entered by the user.
    :rtype: str

    """
    try:
        # Linux specific
        #
        # Call to select can only be done like this on UNIX
        rlist, _, _ = select.select([sys.stdin], [], [], timeout)
        if not rlist:
            raise errors.Error(
                "Timed out waiting for answer to prompt '{0}'".format(prompt))
        return rlist[0].readline()
    except OSError:
        # Windows specific
        #
        # No way with select to make a timeout to the user input on Windows,
        # as select only supports socket in this case.
        # So no timeout on Windows for now.
        return sys.stdin.readline()


WINDOWS_DEFAULT_FOLDERS = {
    'config': 'C:\\Certbot',
    'work': 'C:\\Certbot\\lib',
    'logs': 'C:\\Certbot\\log',
}
LINUX_DEFAULT_FOLDERS = {
    'config': '/etc/letsencrypt',
    'work': '/var/lib/letsencrypt',
    'logs': '/var/log/letsencrypt',
}


def get_default_folder(folder_type):
    # type: (str) -> str
    """
    Return the relevant default folder for the current OS

    :param str folder_type: The type of folder to retrieve (config, work or logs)

    :returns: The relevant default folder.
    :rtype: str

    """
    if os.name != 'nt':
        # Linux specific
        return LINUX_DEFAULT_FOLDERS[folder_type]
    # Windows specific
    return WINDOWS_DEFAULT_FOLDERS[folder_type]


def underscores_for_unsupported_characters_in_path(path):
    # type: (str) -> str
    """
    Replace unsupported characters in path for current OS by underscores.
    :param str path: the path to normalize
    :return: the normalized path
    :rtype: str
    """
    if os.name != 'nt':
        # Linux specific
        return path

    # Windows specific
    drive, tail = os.path.splitdrive(path)
    return drive + tail.replace(':', '_')


def execute_command(cmd_name, shell_cmd, env=None):
    # type: (str, str, Optional[dict]) -> Tuple[str, str]
    """
    Run a command:
        - on Linux command will be run by the standard shell selected with Popen(shell=True)
        - on Windows command will be run in a Powershell shell

    :param str cmd_name: the user facing name of the hook being run
    :param str shell_cmd: shell command to execute
    :param dict env: environ to pass into Popen

    :returns: `tuple` (`str` stderr, `str` stdout)
    """
    logger.info("Running %s command: %s", cmd_name, shell_cmd)

    if POSIX_MODE:
        cmd = subprocess.Popen(shell_cmd, shell=True, stdout=subprocess.PIPE,
                               stderr=subprocess.PIPE, universal_newlines=True,
                               env=env)
    else:
        line = ['powershell.exe', '-Command', shell_cmd]
        cmd = subprocess.Popen(line, stdout=subprocess.PIPE, stderr=subprocess.PIPE,
                               universal_newlines=True, env=env)

    # universal_newlines causes Popen.communicate()
    # to return str objects instead of bytes in Python 3
    out, err = cmd.communicate()
    base_cmd = os.path.basename(shell_cmd.split(None, 1)[0])
    if out:
        logger.info('Output from %s command %s:\n%s', cmd_name, base_cmd, out)
    if cmd.returncode != 0:
        logger.error('%s command "%s" returned error code %d',
                     cmd_name, shell_cmd, cmd.returncode)
    if err:
        logger.error('Error output from %s command %s:\n%s', cmd_name, base_cmd, err)
    return err, out