ethereum.forks.istanbul.vm.interpreterethereum.forks.muir_glacier.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

62
STACK_DEPTH_LIMIT = Uint(1024)

MAX_CODE_SIZE

63
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. `touched_accounts`: Accounts that have been touched.
  6. `error`: The error from the execution if any.
66
@final
67
@dataclass
class MessageCallOutput:

gas_left

82
    gas_left: Uint

refund_counter

83
    refund_counter: U256

logs

84
    logs: Tuple[Log, ...]

accounts_to_delete

85
    accounts_to_delete: Set[Address]

touched_accounts

86
    touched_accounts: Set[Address]

error

87
    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:
91
    <snip>
106
    tx_state = message.tx_env.state
107
    refund_counter = U256(0)
108
    if message.target == Bytes0(b""):
109
        is_collision = account_has_code_or_nonce(
110
            tx_state, message.current_target
111
        ) or account_has_storage(tx_state, message.current_target)
112
        if is_collision:
113
            return MessageCallOutput(
114
                gas_left=Uint(0),
115
                refund_counter=U256(0),
116
                logs=tuple(),
117
                accounts_to_delete=set(),
118
                touched_accounts=set(),
119
                error=AddressCollision(),
120
            )
121
        else:
122
            evm = process_create_message(message)
123
    else:
124
        evm = process_message(message)
125
        if account_exists_and_is_empty(tx_state, Address(message.target)):
126
            evm.touched_accounts.add(Address(message.target))
127
128
    if evm.error:
129
        logs: Tuple[Log, ...] = ()
130
        accounts_to_delete = set()
131
        touched_accounts = set()
132
    else:
133
        logs = evm.logs
134
        accounts_to_delete = evm.accounts_to_delete
135
        touched_accounts = evm.touched_accounts
136
        refund_counter += U256(evm.refund_counter)
137
138
    tx_end = TransactionEnd(
139
        int(message.gas) - int(evm.gas_left), evm.output, evm.error
140
    )
141
    evm_trace(evm, tx_end)
142
143
    return MessageCallOutput(
144
        gas_left=evm.gas_left,
145
        refund_counter=refund_counter,
146
        logs=logs,
147
        accounts_to_delete=accounts_to_delete,
148
        touched_accounts=touched_accounts,
149
        error=evm.error,
150
    )

process_create_message

Executes a call to create a smart contract.

Parameters

message : Transaction specific items.

Returns

evm: :py:class:~ethereum.forks.istanbul.vm.Evm~ethereum.forks.muir_glacier.vm.Evm Items containing execution specific objects.

def process_create_message(message: Message) -> Evm:
154
    <snip>
168
    tx_state = message.tx_env.state
169
    # take snapshot of state before processing the message
170
    snapshot = copy_tx_state(tx_state)
171
172
    # If the address where the account is being created has storage, it is
173
    # destroyed. This can only happen in the following highly unlikely
174
    # circumstances:
175
    # * The address created by a `CREATE` call collides with a subsequent
176
    #   `CREATE` or `CREATE2` call.
177
    # * The first `CREATE` happened before Spurious Dragon and left empty
178
    #   code.
179
    destroy_storage(tx_state, message.current_target)
180
181
    # In the previously mentioned edge case the preexisting storage is ignored
182
    # for gas refund purposes. In order to do this we must track created
183
    # accounts.
184
    mark_account_created(tx_state, message.current_target)
185
186
    increment_nonce(tx_state, message.current_target)
187
    evm = process_message(message)
188
    if not evm.error:
189
        contract_code = evm.output
190
        contract_code_gas = (
191
            ulen(contract_code) * GasCosts.CODE_DEPOSIT_PER_BYTE
192
        )
193
        try:
194
            charge_gas(evm, contract_code_gas)
195
            if len(contract_code) > MAX_CODE_SIZE:
196
                raise OutOfGasError
197
        except ExceptionalHalt as error:
198
            restore_tx_state(tx_state, snapshot)
199
            evm.gas_left = Uint(0)
200
            evm.output = b""
201
            evm.error = error
202
        else:
203
            set_code(tx_state, message.current_target, contract_code)
204
    else:
205
        restore_tx_state(tx_state, snapshot)
206
    return evm

process_message

Move ether and execute the relevant code.

Parameters

message : Transaction specific items.

Returns

evm: :py:class:~ethereum.forks.istanbul.vm.Evm~ethereum.forks.muir_glacier.vm.Evm Items containing execution specific objects

def process_message(message: Message) -> Evm:
210
    <snip>
224
    tx_state = message.tx_env.state
225
    if message.depth > STACK_DEPTH_LIMIT:
226
        raise StackDepthLimitError("Stack depth limit reached")
227
228
    code = message.code
229
    valid_jump_destinations = get_valid_jump_destinations(code)
230
    evm = Evm(
231
        pc=Uint(0),
232
        stack=[],
233
        memory=bytearray(),
234
        code=code,
235
        gas_left=message.gas,
236
        valid_jump_destinations=valid_jump_destinations,
237
        logs=(),
238
        refund_counter=0,
239
        running=True,
240
        message=message,
241
        output=b"",
242
        accounts_to_delete=set(),
243
        touched_accounts=set(),
244
        return_data=b"",
245
        error=None,
246
    )
247
248
    # take snapshot of state before processing the message
249
    snapshot = copy_tx_state(tx_state)
250
251
    touch_account(tx_state, message.current_target)
252
253
    if message.should_transfer_value and message.value != 0:
254
        move_ether(
255
            tx_state,
256
            message.caller,
257
            message.current_target,
258
            message.value,
259
        )
260
261
    try:
262
        if evm.message.code_address in PRE_COMPILED_CONTRACTS:
263
            evm_trace(evm, PrecompileStart(evm.message.code_address))
264
            PRE_COMPILED_CONTRACTS[evm.message.code_address](evm)
265
            evm_trace(evm, PrecompileEnd())
266
        else:
267
            while evm.running and evm.pc < ulen(evm.code):
268
                try:
269
                    op = Ops(evm.code[evm.pc])
270
                except ValueError as e:
271
                    raise InvalidOpcode(evm.code[evm.pc]) from e
272
273
                evm_trace(evm, OpStart(op))
274
                op_implementation[op](evm)
275
                evm_trace(evm, OpEnd())
276
277
            evm_trace(evm, EvmStop(Ops.STOP))
278
279
    except ExceptionalHalt as error:
280
        evm_trace(evm, OpException(error))
281
        evm.gas_left = Uint(0)
282
        evm.output = b""
283
        evm.error = error
284
    except Revert as error:
285
        evm_trace(evm, OpException(error))
286
        evm.error = error
287
288
    if evm.error:
289
        restore_tx_state(tx_state, snapshot)
290
    return evm