update ceph source to reef 18.2.0

[ceph.git] / ceph / src / ceph-volume / ceph_volume / decorators.py

import os
import sys
from ceph_volume import terminal, exceptions
from functools import wraps


def needs_root(func):
    """
    Check for super user privileges on functions/methods. Raise
    ``SuperUserError`` with a nice message.
    """
    @wraps(func)
    def is_root(*a, **kw):
        if not os.getuid() == 0 and not os.environ.get('CEPH_VOLUME_SKIP_NEEDS_ROOT', False):
            raise exceptions.SuperUserError()
        return func(*a, **kw)
    return is_root


def catches(catch=None, handler=None, exit=True):
    """
    Very simple decorator that tries any of the exception(s) passed in as
    a single exception class or tuple (containing multiple ones) returning the
    exception message and optionally handling the problem if it rises with the
    handler if it is provided.

    So instead of douing something like this::

        def bar():
            try:
                some_call()
                print("Success!")
            except TypeError, exc:
                print("Error while handling some call: %s" % exc)
                sys.exit(1)

    You would need to decorate it like this to have the same effect::

        @catches(TypeError)
        def bar():
            some_call()
            print("Success!")

    If multiple exceptions need to be caught they need to be provided as a
    tuple::

        @catches((TypeError, AttributeError))
        def bar():
            some_call()
            print("Success!")
    """
    catch = catch or Exception

    def decorate(f):

        @wraps(f)
        def newfunc(*a, **kw):
            try:
                return f(*a, **kw)
            except catch as e:
                import logging
                logger = logging.getLogger('ceph_volume')
                logger.exception('exception caught by decorator')
                if os.environ.get('CEPH_VOLUME_DEBUG'):
                    raise
                if handler:
                    return handler(e)
                else:
                    sys.stderr.write(make_exception_message(e))
                    if exit:
                        sys.exit(1)
        return newfunc

    return decorate

#
# Decorator helpers
#


def make_exception_message(exc):
    """
    An exception is passed in and this function
    returns the proper string depending on the result
    so it is readable enough.
    """
    if str(exc):
        return '%s %s: %s\n' % (terminal.red_arrow, exc.__class__.__name__, exc)
    else:
        return '%s %s\n' % (terminal.red_arrow, exc.__class__.__name__)