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__all__ = [
'BaseConstructor',
'SafeConstructor',
'FullConstructor',
'UnsafeConstructor',
'Constructor',
'ConstructorError'
]
from .error import *
from .nodes import *
import collections.abc, datetime, base64, binascii, re, sys, types
class ConstructorError(MarkedYAMLError):
pass
class BaseConstructor:
yaml_constructors = {}
yaml_multi_constructors = {}
def __init__(self):
self.constructed_objects = {}
self.recursive_objects = {}
self.state_generators = []
self.deep_construct = False
def check_data(self):
# If there are more documents available?
return self.check_node()
def check_state_key(self, key):
"""Block special attributes/methods from being set in a newly created
object, to prevent user-controlled methods from being called during
deserialization"""
if self.get_state_keys_blacklist_regexp().match(key):
raise ConstructorError(None, None,
"blacklisted key '%s' in instance state found" % (key,), None)
def get_data(self):
# Construct and return the next document.
if self.check_node():
return self.construct_document(self.get_node())
def get_single_data(self):
# Ensure that the stream contains a single document and construct it.
node = self.get_single_node()
if node is not None:
return self.construct_document(node)
return None
def construct_document(self, node):
data = self.construct_object(node)
while self.state_generators:
state_generators = self.state_generators
self.state_generators = []
for generator in state_generators:
for dummy in generator:
pass
self.constructed_objects = {}
self.recursive_objects = {}
self.deep_construct = False
return data
def construct_object(self, node, deep=False):
if node in self.constructed_objects:
return self.constructed_objects[node]
if deep:
old_deep = self.deep_construct
self.deep_construct = True
if node in self.recursive_objects:
raise ConstructorError(None, None,
"found unconstructable recursive node", node.start_mark)
self.recursive_objects[node] = None
constructor = None
tag_suffix = None
if node.tag in self.yaml_constructors:
constructor = self.yaml_constructors[node.tag]
else:
for tag_prefix in self.yaml_multi_constructors:
if tag_prefix is not None and node.tag.startswith(tag_prefix):
tag_suffix = node.tag[len(tag_prefix):]
constructor = self.yaml_multi_constructors[tag_prefix]
break
else:
if None in self.yaml_multi_constructors:
tag_suffix = node.tag
constructor = self.yaml_multi_constructors[None]
elif None in self.yaml_constructors:
constructor = self.yaml_constructors[None]
elif isinstance(node, ScalarNode):
constructor = self.__class__.construct_scalar
elif isinstance(node, SequenceNode):
constructor = self.__class__.construct_sequence
elif isinstance(node, MappingNode):
constructor = self.__class__.construct_mapping
if tag_suffix is None:
data = constructor(self, node)
else:
data = constructor(self, tag_suffix, node)
if isinstance(data, types.GeneratorType):
generator = data
data = next(generator)
if self.deep_construct:
for dummy in generator:
pass
else:
self.state_generators.append(generator)
self.constructed_objects[node] = data
del self.recursive_objects[node]
if deep:
self.deep_construct = old_deep
return data
def construct_scalar(self, node):
if not isinstance(node, ScalarNode):
raise ConstructorError(None, None,
"expected a scalar node, but found %s" % node.id,
node.start_mark)
return node.value
def construct_sequence(self, node, deep=False):
if not isinstance(node, SequenceNode):
raise ConstructorError(None, None,
"expected a sequence node, but found %s" % node.id,
node.start_mark)
return [self.construct_object(child, deep=deep)
for child in node.value]
def construct_mapping(self, node, deep=False):
if not isinstance(node, MappingNode):
raise ConstructorError(None, None,
"expected a mapping node, but found %s" % node.id,
node.start_mark)
mapping = {}
for key_node, value_node in node.value:
key = self.construct_object(key_node, deep=deep)
if not isinstance(key, collections.abc.Hashable):
raise ConstructorError("while constructing a mapping", node.start_mark,
"found unhashable key", key_node.start_mark)
value = self.construct_object(value_node, deep=deep)
mapping[key] = value
return mapping
def construct_pairs(self, node, deep=False):
if not isinstance(node, MappingNode):
raise ConstructorError(None, None,
"expected a mapping node, but found %s" % node.id,
node.start_mark)
pairs = []
for key_node, value_node in node.value:
key = self.construct_object(key_node, deep=deep)
value = self.construct_object(value_node, deep=deep)
pairs.append((key, value))
return pairs
@classmethod
def add_constructor(cls, tag, constructor):
if not 'yaml_constructors' in cls.__dict__:
cls.yaml_constructors = cls.yaml_constructors.copy()
cls.yaml_constructors[tag] = constructor
@classmethod
def add_multi_constructor(cls, tag_prefix, multi_constructor):
if not 'yaml_multi_constructors' in cls.__dict__:
cls.yaml_multi_constructors = cls.yaml_multi_constructors.copy()
cls.yaml_multi_constructors[tag_prefix] = multi_constructor
class SafeConstructor(BaseConstructor):
def construct_scalar(self, node):
if isinstance(node, MappingNode):
for key_node, value_node in node.value:
if key_node.tag == 'tag:yaml.org,2002:value':
return self.construct_scalar(value_node)
return super().construct_scalar(node)
def flatten_mapping(self, node):
merge = []
index = 0
while index < len(node.value):
key_node, value_node = node.value[index]
if key_node.tag == 'tag:yaml.org,2002:merge':
del node.value[index]
if isinstance(value_node, MappingNode):
self.flatten_mapping(value_node)
merge.extend(value_node.value)
elif isinstance(value_node, SequenceNode):
submerge = []
for subnode in value_node.value:
if not isinstance(subnode, MappingNode):
raise ConstructorError("while constructing a mapping",
node.start_mark,
"expected a mapping for merging, but found %s"
% subnode.id, subnode.start_mark)
self.flatten_mapping(subnode)
submerge.append(subnode.value)
submerge.reverse()
for value in submerge:
merge.extend(value)
else:
raise ConstructorError("while constructing a mapping", node.start_mark,
"expected a mapping or list of mappings for merging, but found %s"
% value_node.id, value_node.start_mark)
elif key_node.tag == 'tag:yaml.org,2002:value':
key_node.tag = 'tag:yaml.org,2002:str'
index += 1
else:
index += 1
if merge:
node.value = merge + node.value
def construct_mapping(self, node, deep=False):
if isinstance(node, MappingNode):
self.flatten_mapping(node)
return super().construct_mapping(node, deep=deep)
def construct_yaml_null(self, node):
self.construct_scalar(node)
return None
bool_values = {
'yes': True,
'no': False,
'true': True,
'false': False,
'on': True,
'off': False,
}
def construct_yaml_bool(self, node):
value = self.construct_scalar(node)
return self.bool_values[value.lower()]
def construct_yaml_int(self, node):
value = self.construct_scalar(node)
value = value.replace('_', '')
sign = +1
if value[0] == '-':
sign = -1
if value[0] in '+-':
value = value[1:]
if value == '0':
return 0
elif value.startswith('0b'):
return sign*int(value[2:], 2)
elif value.startswith('0x'):
return sign*int(value[2:], 16)
elif value[0] == '0':
return sign*int(value, 8)
elif ':' in value:
digits = [int(part) for part in value.split(':')]
digits.reverse()
base = 1
value = 0
for digit in digits:
value += digit*base
base *= 60
return sign*value
else:
return sign*int(value)
inf_value = 1e300
while inf_value != inf_value*inf_value:
inf_value *= inf_value
nan_value = -inf_value/inf_value # Trying to make a quiet NaN (like C99).
def construct_yaml_float(self, node):
value = self.construct_scalar(node)
value = value.replace('_', '').lower()
sign = +1
if value[0] == '-':
sign = -1
if value[0] in '+-':
value = value[1:]
if value == '.inf':
return sign*self.inf_value
elif value == '.nan':
return self.nan_value
elif ':' in value:
digits = [float(part) for part in value.split(':')]
digits.reverse()
base = 1
value = 0.0
for digit in digits:
value += digit*base
base *= 60
return sign*value
else:
return sign*float(value)
def construct_yaml_binary(self, node):
try:
value = self.construct_scalar(node).encode('ascii')
except UnicodeEncodeError as exc:
raise ConstructorError(None, None,
"failed to convert base64 data into ascii: %s" % exc,
node.start_mark)
try:
if hasattr(base64, 'decodebytes'):
return base64.decodebytes(value)
else:
return base64.decodestring(value)
except binascii.Error as exc:
raise ConstructorError(None, None,
"failed to decode base64 data: %s" % exc, node.start_mark)
timestamp_regexp = re.compile(
r'''^(?P<year>[0-9][0-9][0-9][0-9])
-(?P<month>[0-9][0-9]?)
-(?P<day>[0-9][0-9]?)
(?:(?:[Tt]|[ \t]+)
(?P<hour>[0-9][0-9]?)
:(?P<minute>[0-9][0-9])
:(?P<second>[0-9][0-9])
(?:\.(?P<fraction>[0-9]*))?
(?:[ \t]*(?P<tz>Z|(?P<tz_sign>[-+])(?P<tz_hour>[0-9][0-9]?)
(?::(?P<tz_minute>[0-9][0-9]))?))?)?$''', re.X)
def construct_yaml_timestamp(self, node):
value = self.construct_scalar(node)
match = self.timestamp_regexp.match(node.value)
values = match.groupdict()
year = int(values['year'])
month = int(values['month'])
day = int(values['day'])
if not values['hour']:
return datetime.date(year, month, day)
hour = int(values['hour'])
minute = int(values['minute'])
second = int(values['second'])
fraction = 0
tzinfo = None
if values['fraction']:
fraction = values['fraction'][:6]
while len(fraction) < 6:
fraction += '0'
fraction = int(fraction)
if values['tz_sign']:
tz_hour = int(values['tz_hour'])
tz_minute = int(values['tz_minute'] or 0)
delta = datetime.timedelta(hours=tz_hour, minutes=tz_minute)
if values['tz_sign'] == '-':
delta = -delta
tzinfo = datetime.timezone(delta)
elif values['tz']:
tzinfo = datetime.timezone.utc
return datetime.datetime(year, month, day, hour, minute, second, fraction,
tzinfo=tzinfo)
def construct_yaml_omap(self, node):
# Note: we do not check for duplicate keys, because it's too
# CPU-expensive.
omap = []
yield omap
if not isinstance(node, SequenceNode):
raise ConstructorError("while constructing an ordered map", node.start_mark,
"expected a sequence, but found %s" % node.id, node.start_mark)
for subnode in node.value:
if not isinstance(subnode, MappingNode):
raise ConstructorError("while constructing an ordered map", node.start_mark,
"expected a mapping of length 1, but found %s" % subnode.id,
subnode.start_mark)
if len(subnode.value) != 1:
raise ConstructorError("while constructing an ordered map", node.start_mark,
"expected a single mapping item, but found %d items" % len(subnode.value),
subnode.start_mark)
key_node, value_node = subnode.value[0]
key = self.construct_object(key_node)
value = self.construct_object(value_node)
omap.append((key, value))
def construct_yaml_pairs(self, node):
# Note: the same code as `construct_yaml_omap`.
pairs = []
yield pairs
if not isinstance(node, SequenceNode):
raise ConstructorError("while constructing pairs", node.start_mark,
"expected a sequence, but found %s" % node.id, node.start_mark)
for subnode in node.value:
if not isinstance(subnode, MappingNode):
raise ConstructorError("while constructing pairs", node.start_mark,
"expected a mapping of length 1, but found %s" % subnode.id,
subnode.start_mark)
if len(subnode.value) != 1:
raise ConstructorError("while constructing pairs", node.start_mark,
"expected a single mapping item, but found %d items" % len(subnode.value),
subnode.start_mark)
key_node, value_node = subnode.value[0]
key = self.construct_object(key_node)
value = self.construct_object(value_node)
pairs.append((key, value))
def construct_yaml_set(self, node):
data = set()
yield data
value = self.construct_mapping(node)
data.update(value)
def construct_yaml_str(self, node):
return self.construct_scalar(node)
def construct_yaml_seq(self, node):
data = []
yield data
data.extend(self.construct_sequence(node))
def construct_yaml_map(self, node):
data = {}
yield data
value = self.construct_mapping(node)
data.update(value)
def construct_yaml_object(self, node, cls):
data = cls.__new__(cls)
yield data
if hasattr(data, '__setstate__'):
state = self.construct_mapping(node, deep=True)
data.__setstate__(state)
else:
state = self.construct_mapping(node)
data.__dict__.update(state)
def construct_undefined(self, node):
raise ConstructorError(None, None,
"could not determine a constructor for the tag %r" % node.tag,
node.start_mark)
SafeConstructor.add_constructor(
'tag:yaml.org,2002:null',
SafeConstructor.construct_yaml_null)
SafeConstructor.add_constructor(
'tag:yaml.org,2002:bool',
SafeConstructor.construct_yaml_bool)
SafeConstructor.add_constructor(
'tag:yaml.org,2002:int',
SafeConstructor.construct_yaml_int)
SafeConstructor.add_constructor(
'tag:yaml.org,2002:float',
SafeConstructor.construct_yaml_float)
SafeConstructor.add_constructor(
'tag:yaml.org,2002:binary',
SafeConstructor.construct_yaml_binary)
SafeConstructor.add_constructor(
'tag:yaml.org,2002:timestamp',
SafeConstructor.construct_yaml_timestamp)
SafeConstructor.add_constructor(
'tag:yaml.org,2002:omap',
SafeConstructor.construct_yaml_omap)
SafeConstructor.add_constructor(
'tag:yaml.org,2002:pairs',
SafeConstructor.construct_yaml_pairs)
SafeConstructor.add_constructor(
'tag:yaml.org,2002:set',
SafeConstructor.construct_yaml_set)
SafeConstructor.add_constructor(
'tag:yaml.org,2002:str',
SafeConstructor.construct_yaml_str)
SafeConstructor.add_constructor(
'tag:yaml.org,2002:seq',
SafeConstructor.construct_yaml_seq)
SafeConstructor.add_constructor(
'tag:yaml.org,2002:map',
SafeConstructor.construct_yaml_map)
SafeConstructor.add_constructor(None,
SafeConstructor.construct_undefined)
class FullConstructor(SafeConstructor):
# 'extend' is blacklisted because it is used by
# construct_python_object_apply to add `listitems` to a newly generate
# python instance
def get_state_keys_blacklist(self):
return ['^extend$', '^__.*__$']
def get_state_keys_blacklist_regexp(self):
if not hasattr(self, 'state_keys_blacklist_regexp'):
self.state_keys_blacklist_regexp = re.compile('(' + '|'.join(self.get_state_keys_blacklist()) + ')')
return self.state_keys_blacklist_regexp
def construct_python_str(self, node):
return self.construct_scalar(node)
def construct_python_unicode(self, node):
return self.construct_scalar(node)
def construct_python_bytes(self, node):
try:
value = self.construct_scalar(node).encode('ascii')
except UnicodeEncodeError as exc:
raise ConstructorError(None, None,
"failed to convert base64 data into ascii: %s" % exc,
node.start_mark)
try:
if hasattr(base64, 'decodebytes'):
return base64.decodebytes(value)
else:
return base64.decodestring(value)
except binascii.Error as exc:
raise ConstructorError(None, None,
"failed to decode base64 data: %s" % exc, node.start_mark)
def construct_python_long(self, node):
return self.construct_yaml_int(node)
def construct_python_complex(self, node):
return complex(self.construct_scalar(node))
def construct_python_tuple(self, node):
return tuple(self.construct_sequence(node))
def find_python_module(self, name, mark, unsafe=False):
if not name:
raise ConstructorError("while constructing a Python module", mark,
"expected non-empty name appended to the tag", mark)
if unsafe:
try:
__import__(name)
except ImportError as exc:
raise ConstructorError("while constructing a Python module", mark,
"cannot find module %r (%s)" % (name, exc), mark)
if name not in sys.modules:
raise ConstructorError("while constructing a Python module", mark,
"module %r is not imported" % name, mark)
return sys.modules[name]
def find_python_name(self, name, mark, unsafe=False):
if not name:
raise ConstructorError("while constructing a Python object", mark,
"expected non-empty name appended to the tag", mark)
if '.' in name:
module_name, object_name = name.rsplit('.', 1)
else:
module_name = 'builtins'
object_name = name
if unsafe:
try:
__import__(module_name)
except ImportError as exc:
raise ConstructorError("while constructing a Python object", mark,
"cannot find module %r (%s)" % (module_name, exc), mark)
if module_name not in sys.modules:
raise ConstructorError("while constructing a Python object", mark,
"module %r is not imported" % module_name, mark)
module = sys.modules[module_name]
if not hasattr(module, object_name):
raise ConstructorError("while constructing a Python object", mark,
"cannot find %r in the module %r"
% (object_name, module.__name__), mark)
return getattr(module, object_name)
def construct_python_name(self, suffix, node):
value = self.construct_scalar(node)
if value:
raise ConstructorError("while constructing a Python name", node.start_mark,
"expected the empty value, but found %r" % value, node.start_mark)
return self.find_python_name(suffix, node.start_mark)
def construct_python_module(self, suffix, node):
value = self.construct_scalar(node)
if value:
raise ConstructorError("while constructing a Python module", node.start_mark,
"expected the empty value, but found %r" % value, node.start_mark)
return self.find_python_module(suffix, node.start_mark)
def make_python_instance(self, suffix, node,
args=None, kwds=None, newobj=False, unsafe=False):
if not args:
args = []
if not kwds:
kwds = {}
cls = self.find_python_name(suffix, node.start_mark)
if not (unsafe or isinstance(cls, type)):
raise ConstructorError("while constructing a Python instance", node.start_mark,
"expected a class, but found %r" % type(cls),
node.start_mark)
if newobj and isinstance(cls, type):
return cls.__new__(cls, *args, **kwds)
else:
return cls(*args, **kwds)
def set_python_instance_state(self, instance, state, unsafe=False):
if hasattr(instance, '__setstate__'):
instance.__setstate__(state)
else:
slotstate = {}
if isinstance(state, tuple) and len(state) == 2:
state, slotstate = state
if hasattr(instance, '__dict__'):
if not unsafe and state:
for key in state.keys():
self.check_state_key(key)
instance.__dict__.update(state)
elif state:
slotstate.update(state)
for key, value in slotstate.items():
if not unsafe:
self.check_state_key(key)
setattr(instance, key, value)
def construct_python_object(self, suffix, node):
# Format:
# !!python/object:module.name { ... state ... }
instance = self.make_python_instance(suffix, node, newobj=True)
yield instance
deep = hasattr(instance, '__setstate__')
state = self.construct_mapping(node, deep=deep)
self.set_python_instance_state(instance, state)
def construct_python_object_apply(self, suffix, node, newobj=False):
# Format:
# !!python/object/apply # (or !!python/object/new)
# args: [ ... arguments ... ]
# kwds: { ... keywords ... }
# state: ... state ...
# listitems: [ ... listitems ... ]
# dictitems: { ... dictitems ... }
# or short format:
# !!python/object/apply [ ... arguments ... ]
# The difference between !!python/object/apply and !!python/object/new
# is how an object is created, check make_python_instance for details.
if isinstance(node, SequenceNode):
args = self.construct_sequence(node, deep=True)
kwds = {}
state = {}
listitems = []
dictitems = {}
else:
value = self.construct_mapping(node, deep=True)
args = value.get('args', [])
kwds = value.get('kwds', {})
state = value.get('state', {})
listitems = value.get('listitems', [])
dictitems = value.get('dictitems', {})
instance = self.make_python_instance(suffix, node, args, kwds, newobj)
if state:
self.set_python_instance_state(instance, state)
if listitems:
instance.extend(listitems)
if dictitems:
for key in dictitems:
instance[key] = dictitems[key]
return instance
def construct_python_object_new(self, suffix, node):
return self.construct_python_object_apply(suffix, node, newobj=True)
FullConstructor.add_constructor(
'tag:yaml.org,2002:python/none',
FullConstructor.construct_yaml_null)
FullConstructor.add_constructor(
'tag:yaml.org,2002:python/bool',
FullConstructor.construct_yaml_bool)
FullConstructor.add_constructor(
'tag:yaml.org,2002:python/str',
FullConstructor.construct_python_str)
FullConstructor.add_constructor(
'tag:yaml.org,2002:python/unicode',
FullConstructor.construct_python_unicode)
FullConstructor.add_constructor(
'tag:yaml.org,2002:python/bytes',
FullConstructor.construct_python_bytes)
FullConstructor.add_constructor(
'tag:yaml.org,2002:python/int',
FullConstructor.construct_yaml_int)
FullConstructor.add_constructor(
'tag:yaml.org,2002:python/long',
FullConstructor.construct_python_long)
FullConstructor.add_constructor(
'tag:yaml.org,2002:python/float',
FullConstructor.construct_yaml_float)
FullConstructor.add_constructor(
'tag:yaml.org,2002:python/complex',
FullConstructor.construct_python_complex)
FullConstructor.add_constructor(
'tag:yaml.org,2002:python/list',
FullConstructor.construct_yaml_seq)
FullConstructor.add_constructor(
'tag:yaml.org,2002:python/tuple',
FullConstructor.construct_python_tuple)
FullConstructor.add_constructor(
'tag:yaml.org,2002:python/dict',
FullConstructor.construct_yaml_map)
FullConstructor.add_multi_constructor(
'tag:yaml.org,2002:python/name:',
FullConstructor.construct_python_name)
class UnsafeConstructor(FullConstructor):
def find_python_module(self, name, mark):
return super(UnsafeConstructor, self).find_python_module(name, mark, unsafe=True)
def find_python_name(self, name, mark):
return super(UnsafeConstructor, self).find_python_name(name, mark, unsafe=True)
def make_python_instance(self, suffix, node, args=None, kwds=None, newobj=False):
return super(UnsafeConstructor, self).make_python_instance(
suffix, node, args, kwds, newobj, unsafe=True)
def set_python_instance_state(self, instance, state):
return super(UnsafeConstructor, self).set_python_instance_state(
instance, state, unsafe=True)
UnsafeConstructor.add_multi_constructor(
'tag:yaml.org,2002:python/module:',
UnsafeConstructor.construct_python_module)
UnsafeConstructor.add_multi_constructor(
'tag:yaml.org,2002:python/object:',
UnsafeConstructor.construct_python_object)
UnsafeConstructor.add_multi_constructor(
'tag:yaml.org,2002:python/object/new:',
UnsafeConstructor.construct_python_object_new)
UnsafeConstructor.add_multi_constructor(
'tag:yaml.org,2002:python/object/apply:',
UnsafeConstructor.construct_python_object_apply)
# Constructor is same as UnsafeConstructor. Need to leave this in place in case
# people have extended it directly.
class Constructor(UnsafeConstructor):
pass
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