ethereum.forks.tangerine_whistle.vm.interpreterethereum.forks.spurious_dragon.vm.interpreter

Ethereum Virtual Machine (EVM) Interpreter.

.. contents:: Table of Contents :backlinks: none :local:

Introduction

A straightforward interpreter that executes EVM code.

STACK_DEPTH_LIMIT

61
STACK_DEPTH_LIMIT = Uint(1024)

MAX_CODE_SIZE

62
MAX_CODE_SIZE = 0x6000

MessageCallOutput

Output of a particular message call.

Contains the following:

  1. `gas_left`: remaining gas after execution.
  2. `refund_counter`: gas to refund after execution.
  3. `logs`: list of `Log` generated during execution.
  4. `accounts_to_delete`: Contracts which have self-destructed.
  5. `error`: The error from the execution if any.
  1. `gas_left`: remaining gas after execution.
  2. `refund_counter`: gas to refund after execution.
  3. `logs`: list of `Log` generated during execution.
  4. `accounts_to_delete`: Contracts which have self-destructed.
  5. `touched_accounts`: Accounts that have been touched.
  6. `error`: The error from the execution if any.
65
@dataclass
class MessageCallOutput:

gas_left

80
    gas_left: Uint

refund_counter

81
    refund_counter: U256

logs

82
    logs: Tuple[Log, ...]

accounts_to_delete

83
    accounts_to_delete: Set[Address]

touched_accounts

84
    touched_accounts: Set[Address]

error

85
    error: Optional[EthereumException]

process_message_call

If message.target is empty then it creates a smart contract else it executes a call from the message.caller to the message.target.

Parameters

message : Transaction specific items.

Returns

output : MessageCallOutput Output of the message call

def process_message_call(message: Message) -> MessageCallOutput:
89
    """
90
    If `message.target` is empty then it creates a smart contract
91
    else it executes a call from the `message.caller` to the `message.target`.
92
93
    Parameters
94
    ----------
95
    message :
96
        Transaction specific items.
97
98
    Returns
99
    -------
100
    output : `MessageCallOutput`
101
        Output of the message call
102
103
    """
104
    block_env = message.block_env
105
    refund_counter = U256(0)
106
    if message.target == Bytes0(b""):
107
        is_collision = account_has_code_or_nonce(
108
            block_env.state, message.current_target
109
        ) or account_has_storage(block_env.state, message.current_target)
110
        if is_collision:
111
            return MessageCallOutput(
106
                Uint(0), U256(0), tuple(), set(), AddressCollision()
112
                Uint(0), U256(0), tuple(), set(), set(), AddressCollision()
113
            )
114
        else:
115
            evm = process_create_message(message)
116
    else:
111
        evm = process_message(message)
117
        evm = process_message(message)
118
        if account_exists_and_is_empty(
119
            block_env.state, Address(message.target)
120
        ):
121
            evm.touched_accounts.add(Address(message.target))
122
123
    if evm.error:
124
        logs: Tuple[Log, ...] = ()
115
        accounts_to_delete = set()
125
        accounts_to_delete = set()
126
        touched_accounts = set()
127
    else:
128
        logs = evm.logs
129
        accounts_to_delete = evm.accounts_to_delete
130
        touched_accounts = evm.touched_accounts
131
        refund_counter += U256(evm.refund_counter)
132
133
    tx_end = TransactionEnd(
134
        int(message.gas) - int(evm.gas_left), evm.output, evm.error
135
    )
136
    evm_trace(evm, tx_end)
137
138
    return MessageCallOutput(
139
        gas_left=evm.gas_left,
140
        refund_counter=refund_counter,
141
        logs=logs,
142
        accounts_to_delete=accounts_to_delete,
143
        touched_accounts=touched_accounts,
144
        error=evm.error,
145
    )

process_create_message

Executes a call to create a smart contract.

Parameters

message : Transaction specific items.

Returns

evm: :py:class:~ethereum.forks.tangerine_whistle.vm.Evm~ethereum.forks.spurious_dragon.vm.Evm Items containing execution specific objects.

def process_create_message(message: Message) -> Evm:
149
    """
150
    Executes a call to create a smart contract.
151
152
    Parameters
153
    ----------
154
    message :
155
        Transaction specific items.
156
157
    Returns
158
    -------
146
    evm: :py:class:`~ethereum.forks.tangerine_whistle.vm.Evm`
159
    evm: :py:class:`~ethereum.forks.spurious_dragon.vm.Evm`
160
        Items containing execution specific objects.
161
162
    """
163
    state = message.block_env.state
164
    # take snapshot of state before processing the message
165
    begin_transaction(state)
166
167
    # If the address where the account is being created has storage, it is
168
    # destroyed. This can only happen in the following highly unlikely
169
    # circumstances:
170
    # * The address created by two `CREATE` calls collide.
158
    # * The first `CREATE` left empty code.
171
    # * The first `CREATE` happened before Spurious Dragon and left empty
172
    #   code.
173
    destroy_storage(state, message.current_target)
174
175
    increment_nonce(state, message.current_target)
176
    evm = process_message(message)
177
    if not evm.error:
178
        contract_code = evm.output
179
        contract_code_gas = Uint(len(contract_code)) * GAS_CODE_DEPOSIT
180
        try:
166
            charge_gas(evm, contract_code_gas)
181
            charge_gas(evm, contract_code_gas)
182
            if len(contract_code) > MAX_CODE_SIZE:
183
                raise OutOfGasError
184
        except ExceptionalHalt as error:
185
            rollback_transaction(state)
186
            evm.gas_left = Uint(0)
187
            evm.error = error
188
        else:
189
            set_code(state, message.current_target, contract_code)
190
            commit_transaction(state)
191
    else:
192
        rollback_transaction(state)
193
    return evm

process_message

Move ether and execute the relevant code.

Parameters

message : Transaction specific items.

Returns

evm: :py:class:~ethereum.forks.tangerine_whistle.vm.Evm~ethereum.forks.spurious_dragon.vm.Evm Items containing execution specific objects

def process_message(message: Message) -> Evm:
197
    """
198
    Move ether and execute the relevant code.
199
200
    Parameters
201
    ----------
202
    message :
203
        Transaction specific items.
204
205
    Returns
206
    -------
190
    evm: :py:class:`~ethereum.forks.tangerine_whistle.vm.Evm`
207
    evm: :py:class:`~ethereum.forks.spurious_dragon.vm.Evm`
208
        Items containing execution specific objects
209
210
    """
211
    state = message.block_env.state
212
    if message.depth > STACK_DEPTH_LIMIT:
213
        raise StackDepthLimitError("Stack depth limit reached")
214
215
    # take snapshot of state before processing the message
216
    begin_transaction(state)
217
218
    touch_account(state, message.current_target)
219
220
    if message.should_transfer_value and message.value != 0:
221
        move_ether(
222
            state, message.caller, message.current_target, message.value
223
        )
224
225
    evm = execute_code(message)
226
    if evm.error:
227
        # revert state to the last saved checkpoint
228
        # since the message call resulted in an error
229
        rollback_transaction(state)
230
    else:
231
        commit_transaction(state)
232
    return evm

execute_code

Executes bytecode present in the message.

Parameters

message : Transaction specific items.

Returns

evm: ethereum.vm.EVM Items containing execution specific objects

def execute_code(message: Message) -> Evm:
236
    """
237
    Executes bytecode present in the `message`.
238
239
    Parameters
240
    ----------
241
    message :
242
        Transaction specific items.
243
244
    Returns
245
    -------
246
    evm: `ethereum.vm.EVM`
247
        Items containing execution specific objects
248
249
    """
250
    code = message.code
251
    valid_jump_destinations = get_valid_jump_destinations(code)
252
253
    evm = Evm(
254
        pc=Uint(0),
255
        stack=[],
256
        memory=bytearray(),
257
        code=code,
258
        gas_left=message.gas,
259
        valid_jump_destinations=valid_jump_destinations,
260
        logs=(),
261
        refund_counter=0,
262
        running=True,
263
        message=message,
264
        output=b"",
265
        accounts_to_delete=set(),
266
        touched_accounts=set(),
267
        error=None,
268
    )
269
    try:
270
        if evm.message.code_address in PRE_COMPILED_CONTRACTS:
271
            evm_trace(evm, PrecompileStart(evm.message.code_address))
272
            PRE_COMPILED_CONTRACTS[evm.message.code_address](evm)
273
            evm_trace(evm, PrecompileEnd())
274
            return evm
275
276
        while evm.running and evm.pc < ulen(evm.code):
277
            try:
278
                op = Ops(evm.code[evm.pc])
279
            except ValueError as e:
280
                raise InvalidOpcode(evm.code[evm.pc]) from e
281
282
            evm_trace(evm, OpStart(op))
283
            op_implementation[op](evm)
284
            evm_trace(evm, OpEnd())
285
286
        evm_trace(evm, EvmStop(Ops.STOP))
287
288
    except ExceptionalHalt as error:
289
        evm_trace(evm, OpException(error))
290
        evm.gas_left = Uint(0)
291
        evm.error = error
292
    return evm