# This file is part of cloud-init. See LICENSE file for license information.

"""Common utility functions for interacting with subprocess."""

# TODO move subp shellify and runparts related functions out of util.py

import logging

LOG = logging.getLogger(__name__)

def prepend_base_command(base_command, commands):

    """Ensure user-provided commands start with base_command; warn otherwise.

    Each command is either a list or string. Perform the following:

       - If the command is a list, pop the first element if it is None

       - If the command is a list, insert base_command as the first element if

         not present.

       - When the command is a string not starting with 'base-command', warn.

    Allow flexibility to provide non-base-command environment/config setup if

    needed.

    @commands: List of commands. Each command element is a list or string.

    @return: List of 'fixed up' commands.

    @raise: TypeError on invalid config item type.

    """

    warnings = []

    errors = []

    fixed_commands = []

    for command in commands:

        if isinstance(command, list):

            if command[0] is None:  # Avoid warnings by specifying None

                command = command[1:]

            elif command[0] != base_command:  # Automatically prepend

                command.insert(0, base_command)

        elif isinstance(command, str):

            if not command.startswith('%s ' % base_command):

                warnings.append(command)

        else:

            errors.append(str(command))

            continue

        fixed_commands.append(command)

    if warnings:

        LOG.warning(

            'Non-%s commands in %s config:\n%s',

            base_command, base_command, '\n'.join(warnings))

    if errors:

        raise TypeError(

            'Invalid {name} config.'

            ' These commands are not a string or list:\n{errors}'.format(

                name=base_command, errors='\n'.join(errors)))

    return fixed_commands

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