ethereum.frontier.vm

  1"""
  2Ethereum Virtual Machine (EVM)
  3^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  4
  5.. contents:: Table of Contents
  6    :backlinks: none
  7    :local:
  8
  9Introduction
 10------------
 11
 12The abstract computer which runs the code stored in an
 13`.fork_types.Account`.
 14"""
 15
 16from dataclasses import dataclass
 17from typing import List, Optional, Set, Tuple, Union
 18
 19from ethereum.base_types import U256, Bytes, Bytes0, Uint
 20from ethereum.crypto.hash import Hash32
 21
 22from ..fork_types import Address, Log
 23from ..state import State
 24
 25__all__ = ("Environment", "Evm", "Message")
 26
 27
 28@dataclass
 29class Environment:
 30    """
 31    Items external to the virtual machine itself, provided by the environment.
 32    """
 33
 34    caller: Address
 35    block_hashes: List[Hash32]
 36    origin: Address
 37    coinbase: Address
 38    number: Uint
 39    gas_limit: Uint
 40    gas_price: Uint
 41    time: U256
 42    difficulty: Uint
 43    state: State
 44    traces: List[dict]
 45
 46
 47@dataclass
 48class Message:
 49    """
 50    Items that are used by contract creation or message call.
 51    """
 52
 53    caller: Address
 54    target: Union[Bytes0, Address]
 55    current_target: Address
 56    gas: Uint
 57    value: U256
 58    data: Bytes
 59    code_address: Optional[Address]
 60    code: Bytes
 61    depth: Uint
 62    parent_evm: Optional["Evm"]
 63
 64
 65@dataclass
 66class Evm:
 67    """The internal state of the virtual machine."""
 68
 69    pc: Uint
 70    stack: List[U256]
 71    memory: bytearray
 72    code: Bytes
 73    gas_left: Uint
 74    env: Environment
 75    valid_jump_destinations: Set[Uint]
 76    logs: Tuple[Log, ...]
 77    refund_counter: U256
 78    running: bool
 79    message: Message
 80    output: Bytes
 81    accounts_to_delete: Set[Address]
 82    error: Optional[Exception]
 83
 84
 85def incorporate_child_on_success(evm: Evm, child_evm: Evm) -> None:
 86    """
 87    Incorporate the state of a successful `child_evm` into the parent `evm`.
 88
 89    Parameters
 90    ----------
 91    evm :
 92        The parent `EVM`.
 93    child_evm :
 94        The child evm to incorporate.
 95    """
 96    evm.gas_left += child_evm.gas_left
 97    evm.logs += child_evm.logs
 98    evm.refund_counter += child_evm.refund_counter
 99    evm.accounts_to_delete.update(child_evm.accounts_to_delete)
100
101
102def incorporate_child_on_error(evm: Evm, child_evm: Evm) -> None:
103    """
104    Incorporate the state of an unsuccessful `child_evm` into the parent `evm`.
105
106    Parameters
107    ----------
108    evm :
109        The parent `EVM`.
110    child_evm :
111        The child evm to incorporate.
112    """
113    evm.gas_left += child_evm.gas_left