ceph/src/ceph-volume/ceph_volume/decorators.py

   1 import os
   2 import sys
   3 from ceph_volume import terminal, exceptions
   4 from functools import wraps
   5
   6
   7 def needs_root(func):
   8     """
   9     Check for super user privileges on functions/methods. Raise
  10     ``SuperUserError`` with a nice message.
  11     """
  12     @wraps(func)
  13     def is_root(*a, **kw):
  14         if not os.getuid() == 0 and not os.environ.get('CEPH_VOLUME_SKIP_NEEDS_ROOT', False):
  15             raise exceptions.SuperUserError()
  16         return func(*a, **kw)
  17     return is_root
  18
  19
  20 def catches(catch=None, handler=None, exit=True):
  21     """
  22     Very simple decorator that tries any of the exception(s) passed in as
  23     a single exception class or tuple (containing multiple ones) returning the
  24     exception message and optionally handling the problem if it rises with the
  25     handler if it is provided.
  26
  27     So instead of douing something like this::
  28
  29         def bar():
  30             try:
  31                 some_call()
  32                 print("Success!")
  33             except TypeError, exc:
  34                 print("Error while handling some call: %s" % exc)
  35                 sys.exit(1)
  36
  37     You would need to decorate it like this to have the same effect::
  38
  39         @catches(TypeError)
  40         def bar():
  41             some_call()
  42             print("Success!")
  43
  44     If multiple exceptions need to be caught they need to be provided as a
  45     tuple::
  46
  47         @catches((TypeError, AttributeError))
  48         def bar():
  49             some_call()
  50             print("Success!")
  51     """
  52     catch = catch or Exception
  53
  54     def decorate(f):
  55
  56         @wraps(f)
  57         def newfunc(*a, **kw):
  58             try:
  59                 return f(*a, **kw)
  60             except catch as e:
  61                 import logging
  62                 logger = logging.getLogger('ceph_volume')
  63                 logger.exception('exception caught by decorator')
  64                 if os.environ.get('CEPH_VOLUME_DEBUG'):
  65                     raise
  66                 if handler:
  67                     return handler(e)
  68                 else:
  69                     sys.stderr.write(make_exception_message(e))
  70                     if exit:
  71                         sys.exit(1)
  72         return newfunc
  73
  74     return decorate
  75
  76 #
  77 # Decorator helpers
  78 #
  79
  80
  81 def make_exception_message(exc):
  82     """
  83     An exception is passed in and this function
  84     returns the proper string depending on the result
  85     so it is readable enough.
  86     """
  87     if str(exc):
  88         return '%s %s: %s\n' % (terminal.red_arrow, exc.__class__.__name__, exc)
  89     else:
  90         return '%s %s\n' % (terminal.red_arrow, exc.__class__.__name__)