# ------------------------------------------------------------------------------
# CodeHawk C Analyzer
# Author: Henny Sipma
# ------------------------------------------------------------------------------
# The MIT License (MIT)
#
# Copyright (c) 2017-2020 Kestrel Technology LLC
# Copyright (c) 2021-2022 Henny B. Sipma
# Copyright (c) 2023-2024 Aarno Labs LLC
#
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# The above copyright notice and this permission notice shall be included in all
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# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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# ------------------------------------------------------------------------------
"""External assumption on a function."""
from typing import TYPE_CHECKING
from chc.proof.CFunPODictionaryRecord import CFunPODictionaryRecord, podregistry
import chc.util.fileutil as UF
from chc.util.IndexedTable import IndexedTableValue
if TYPE_CHECKING:
from chc.api.XPredicate import XPredicate
from chc.proof.CFunPODictionary import CFunPODictionary
from chc.proof.CPOPredicate import CPOPredicate
[docs]class AssumptionType(CFunPODictionaryRecord):
"""Base class for assumption types."""
def __init__(
self, pod: "CFunPODictionary", ixval: IndexedTableValue
) -> None:
CFunPODictionaryRecord.__init__(self, pod, ixval)
@property
def is_local_assumption(self) -> bool:
return False
@property
def is_api_assumption(self) -> bool:
return False
@property
def is_global_api_assumption(self) -> bool:
return False
@property
def is_contract_assumption(self) -> bool:
return False
@property
def is_global_assumption(self) -> bool:
return False
def __str__(self) -> str:
return "assumption-type:" + self.tags[0]
[docs]@podregistry.register_tag("la", AssumptionType)
class LocalAssumptionType(AssumptionType):
"""Assumption on local variables within a function.
Used in a context where a property can be reduced to local supporting proof
obligations. An example is assuming that a call to a function preserves all
memory (e.g., does not free any memory).
* args[0]: index of predicate in predicate dictionary
"""
def __init__(
self, pod: "CFunPODictionary", ixval: IndexedTableValue
) -> None:
AssumptionType.__init__(self, pod, ixval)
@property
def predicate(self) -> "CPOPredicate":
return self.pd.get_predicate(self.args[0])
@property
def is_local_assumption(self) -> bool:
return True
def __str__(self) -> str:
return "local:" + str(self.predicate)
[docs]@podregistry.register_tag("aa", AssumptionType)
class ApiAssumptionType(AssumptionType):
"""Assumption on parameters of the function.
This type of assumption gives rise to the corresponding supporting proof
obligations on the arguments in the caller of the function.
The index of the predicate is also used as the api-id for the assumption.
* args[0]: index of predicate in predicate dictionary
"""
def __init__(
self, pod: "CFunPODictionary", ixval: IndexedTableValue
) -> None:
AssumptionType.__init__(self, pod, ixval)
@property
def predicate(self) -> "CPOPredicate":
return self.pd.get_predicate(self.args[0])
@property
def api_id(self) -> int:
return self.args[0]
@property
def is_api_assumption(self) -> bool:
return True
def __str__(self) -> str:
return "api:" + str(self.predicate)
[docs]@podregistry.register_tag("gi", AssumptionType)
class GlobalApiAssumptionType(AssumptionType):
"""Assumption on global variable values upon entry of the function.
Global variables referenced/modified in a function can be viewed as 'ghost'
parameters to a function, where the function may make some assumption about
their value upon function start, but then is responsible for tracking its
value locally (assuming no concurrency, or a form of ownership of the global
variable throughout function execution.
* args[0]: index of predicate in predicate dictionary
"""
def __init__(
self, pod: "CFunPODictionary", ixval: IndexedTableValue
) -> None:
AssumptionType.__init__(self, pod, ixval)
@property
def predicate(self) -> "CPOPredicate":
return self.pd.get_predicate(self.args[0])
@property
def is_global_api_assumption(self) -> bool:
return True
def __str__(self) -> str:
return "global-api:" + str(self.predicate)
[docs]@podregistry.register_tag("ca", AssumptionType)
class PostconditionType(AssumptionType):
"""Assumption on the post-condition of a function called.
Note: this assumption type is referred to as a contract assumption, because
these types of assumption are usually introduced by means of an externally
provided contract.
* args[0]: vid of the callee (local file vid)
* args[1]: index of xpredicate in interface dictionary
"""
def __init__(
self, pod: "CFunPODictionary", ixval: IndexedTableValue
) -> None:
AssumptionType.__init__(self, pod, ixval)
@property
def xpredicate(self) -> "XPredicate":
return self.ifd.get_xpredicate(self.args[1])
@property
def callee(self) -> int:
return self.args[0]
@property
def is_contract_assumption(self) -> bool:
return True
def __str__(self) -> str:
return (
"post-condition-assumption:("
+ str(self.callee)
+ ", "
+ str(self.xpredicate))
[docs]@podregistry.register_tag("ga", AssumptionType)
class GlobalAssumptionType(AssumptionType):
"""Assumption that is asserted globally that is supported globally.
* args[0]: index of xpredicate in interfacedictionary
"""
def __init__(
self, pod: "CFunPODictionary", ixval: IndexedTableValue
) -> None:
AssumptionType.__init__(self, pod, ixval)
@property
def xpredicate(self) -> "XPredicate":
return self.ifd.get_xpredicate(self.args[0])
@property
def is_global_assumption(self) -> bool:
return True
def __str__(self) -> str:
return "global-assumption:" + str(self.xpredicate)