"""This module contains utility functions for the Mythril support package."""
from functools import lru_cache
from typing import Dict
import logging
from eth_hash.auto import keccak
log = logging.getLogger(__name__)
[docs]class Singleton(type):
"""A metaclass type implementing the singleton pattern."""
_instances = {} # type: Dict
def __call__(cls, *args, **kwargs):
"""Delegate the call to an existing resource or a a new one.
This is not thread- or process-safe by default. It must be protected with
a lock.
:param args:
:param kwargs:
:return:
"""
if cls not in cls._instances:
cls._instances[cls] = super(Singleton, cls).__call__(*args, **kwargs)
return cls._instances[cls]
[docs]@lru_cache(maxsize=2**10)
def get_code_hash(code) -> str:
"""
:param code: bytecode
:return: Returns hash of the given bytecode
"""
if type(code) == tuple:
# Temporary hack, since we cannot find symbols of sha3
return str(hash(code))
code = code[2:] if code[:2] == "0x" else code
try:
hash_ = keccak(bytes.fromhex(code))
return "0x" + hash_.hex()
except ValueError:
log.debug("Unable to change the bytecode to bytes. Bytecode: {}".format(code))
return ""
[docs]def sha3(value):
if type(value) == str:
if value[:2] == "0x":
new_hash = keccak(bytes.fromhex(value))
else:
new_hash = keccak(value.encode())
else:
new_hash = keccak(value)
return new_hash
[docs]def zpad(x, l):
"""
Left zero pad value `x` at least to length `l`.
"""
return b"\x00" * max(0, l - len(x)) + x
[docs]def rzpad(value, total_length):
"""
Right zero pad value `x` at least to length `l`.
"""
return value + b"\x00" * max(0, total_length - len(value))